Impiombato v BHP Group Limited

Allesch v Maunz (2000) 203 CLR 172 Aon Risk Services Australia Limited v Australian National University (2009) 239 CLR 175 Australian Securities and Investments Commission v Hellicar (2012) 247 CLR 345 Austructures Pty Ltd v Makin [2014] VSC 544 Bauer Consumer Media Ltd v Evergreen Television Pty Ltd [2019] FCAFC 71 BHP Group Ltd v Impiombato (2022) 276 CLR 611 Binqld Finances Pty Ltd (in liq) v Binetter [2024] FCA 361 Branir Pty Ltd v Owston Nominees (No 2) Pty Ltd (2001) 117 FCR 424 Bridge Shipping Pty Ltd v Grand Shipping SA (1991) 173 CLR 231 Brisbane South Regional Health Authority v Taylor (1996) 186 CLR 541 Bright v Femcare Ltd [2002] FCAFC 243 Brown v Jammal [1995] NSWCA 62 Caason Investments Pty Ltd v Cao (2015) 236 FCR 322 Dare v Pulham (1982) 148 CLR 658 Dyczynski v Gibson (2020) 280 FCR 583 Ethicon Sàrl v Gill (2018) 264 FCR 394 Fox v Percy (2003) 214 CLR 118 Gould v Mount Oxide Mines Ltd (1916) 22 CLR 490 House v The King (1936) 55 CLR 499 Hua Wang Bank Berhad v Federal Commissioner of Taxation (No 15) (2013) 217 FCR 26 Impiombato v BHP Group Limited (No 4) [2023] FCA 1354 Impiombato v BHP Group Limited (No 5) [2024] FCA 591 Cases cited: Ingot Capital Investments Pty Ltd v Macquarie Equity Capital Markets Ltd (2008) 73 NSWLR 653 J Wisbey & Associates Pty Ltd v UBS AG [2021] FCA 36 Karl Suleman Enterprizes Pty Ltd (in liquidation) v Pham [2013] NSWSC 110 Keynes v Rural Directions Pty Ltd (No 4) [2011] FCA 304 Kuligowski v Metrobus (2004) 220 CLR 363 Lantrak Holdings Pty Ltd v Yammine [2023] FCAFC 156 Lee v Lee (2019) 266 CLR 129 Newtronics Pty Ltd v Gjergja [2008] VSCA 117 Nikolay Malakhov Shipping Co Ltd v SEAS Sapfor Ltd (1998) 44 NSWLR 371 Norbis v Norbis (1986) 161 CLR 513 Northern Territory v Sangare (2019) 265 CLR 164 Petrusevski v Bulldogs Rugby League Club Ltd [2003] FCA 61 Precision Plastics Pty Ltd v Demir (1975) 132 CLR 362 Professional Administration Service Centres Pty Ltd v Commissioner of Taxation [2012] FCAFC 180 Provide Nominees Pty Ltd v Australian Securities and Investments Commission (2024) 301 FCR 569 Revian v Dasford Holdings Pty Ltd [2001] FCA 777 Robinson Helicopter Company Incorporated v McDermott [2016] HCA 22 Sent v Jet Corporation of Australia Pty Ltd (1986) 160 CLR 540 Singtel Optus Pty Ltd v Robertson [2024] FCAFC 58 Wang v Hur [2024] QCA 126 Warren v Coombes (1979) 142 CLR 531 Wati v Minister for Immigration and Multicultural Affairs (1997) 78 FCR 543 Wong v Silkfield Pty Ltd (1999) 199 CLR 255 John Levingston, The Law of Affidavits (Federation Press, 2013) Justice Alan Robertson, 'Affidavit Evidence' [2014] Federal Judicial Scholarship Articles

Division: General Division

Registry: Victoria

Number of paragraphs: 393

Date of hearing: 8 November 2024

Counsel for the appellants in VID 989 of 2023 and the respondents in VID 553 of 2024: P W Collinson KC with E L Olivier

Solicitors for the appellants in VID 989 of 2023 and the respondents in VID 553 of 2024: Phi Finney McDonald and Maurice Blackburn Lawyers

Counsel for the appellant in VID 553 of 2024 and the respondent in VID 989 of 2023: W Harris KC with K Loxley, B Cameron and J Moir

Solicitors for the appellant in VID 553 of 2024 and the respondent in VID 989 of 2023: Herbert Smith Freehills

VINCE IMPIOMBATO BETWEEN: First Appellant KLEMWEB NOMINEES PTY LTD (AS TRUSTEE FOR THE KLEMWEB SUPERANNUATION FUND) Second Appellant AND: BHP GROUP LIMITED Respondent

order made by: BEACH, LEE and O'BRYAN JJ DATE OF ORDER: 12 february 2025

THE COURT ORDERS THAT:

1. The appeal be dismissed.
2. The appellants pay the respondent's costs of the appeal. Note: Entry of orders is dealt with in Rule 39.32 of the Federal Court Rules 2011. ORDERS VID 553 of 2024

BETWEEN: BHP GROUP LIMITED Appellant VINCE IMPIOMBATO AND: First Respondent KLEMWEB NOMINEES PTY LTD (AS TRUSTEE FOR THE KLEMWEB SUPERANNUATION FUND) Second Respondent

order made by: BEACH, LEE and O'BRYAN JJ DATE OF ORDER: 12 february 2025

THE COURT ORDERS THAT:

1. The appeal be allowed.
2. Order 2 of the orders of the Court in proceeding VID 549 of 2018 made on 6 June 2024 be set aside.
3. The amendments made to the amended consolidated originating application dated 19 June 2024 take effect on and from 5 December 2023.
4. The amendments made to the further amended consolidated statement of claim dated 19 June 2024 take effect on and from the following dates:
   1. 5 December 2023 in respect of the description of group members in paragraph 3;
   2. 31 May 2018 in respect of all other amendments.
5. By 26 February 2025, each party file a written submission (of no more than three pages) on the question of the costs of the determination of the interlocutory application by the primary judge and of the appeal. The Court will determine the question of costs on the papers. Note: Entry of orders is dealt with in Rule 39.32 of the Federal Court Rules 2011. REASONS FOR JUDGMENT BEACH AND O'BRYAN JJ:

A. Introduction

1. A representative proceeding has been brought against BHP Group Limited alleging that it contravened:
2. rule 3.1 of the ASX Listing Rules and s 674(2) of the Corporations Act 2010 (Cth) (Corporations Act); and
3. the prohibitions against misleading and deceptive conduct in s 1041H(1) of the Corporations Act and s 12DA(1) of the Australian Securities and Investments Commission Act 2001 (Cth) (ASIC Act).
4. BHP Group Limited and BHP Group Plc are parties to an agreement entered into in 2001 which implemented a dual listed company structure under which the two companies operate as if they are a single unified economic entity. It is convenient to refer to BHP Group Limited as "BHP Ltd" and BHP Group Plc as "BHP Plc", and to refer to the notional single unified economic entity comprising BHP Ltd and BHP Plc as "BHP". BHP Ltd is listed on the Australian Securities Exchange (ASX) and its ordinary shares are quoted on that exchange. BHP Plc is listed on the London Stock Exchange (LSE) and the Johannesburg Stock Exchange (JSE) and its ordinary shares are quoted on those exchanges.
5. The allegations made in the representative proceeding arise from the collapse of the Fundão Dam in Brazil at around 3.30 pm on 5 November 2015 (Brazil time). The Fundão Dam supported an iron ore mine in the state of Minas Gerais, Brazil, in which BHP held a substantial indirect interest. The collapse of the Fundão Dam resulted in the release of a significant volume of tailings causing loss of life and damage to property in the vicinity of the dam, and also resulted in adverse commercial consequences for BHP including exposure to remediation costs and disruption to iron ore production.
6. The proceeding has been burdened by numerous interlocutory disputes. Although the proceeding was commenced in 2018, it is listed for trial in 2025. The two appeals before this Court are the latest in the series of interlocutory disputes. The appeals arise from two interlocutory judgments, each of which concerns the description of group members. It is common to refer to the description of group members contained in an originating application or statement of claim as the "group member definition" or "group definition". In these reasons, the expressions "description of group members" and "group definition" are used interchangeably.
7. On 3 November 2023, Moshinsky J made orders refusing to approve the form of opt-out notices proposed by the applicants, and published reasons in Impiombato v BHP Group Limited (No 4) [2023] FCA 1354 (Impiombato No 4). The issue in dispute between the parties, which was resolved by Moshinsky J in Impiombato No 4, concerned the description of the group members contained in the draft opt-out notice proposed by the applicants. That dispute raised the question of the meaning of the description of group members which was set out in the originating application and the statement of claim. The applicants contended that the description covers persons who, during the period from 8 August 2012 to the close of trade on 9 November 2015 inclusive (relevant period), entered into contracts to acquire ordinary shares in BHP Ltd or BHP Plc on any trading platform or exchange, not limited to the ASX, the LSE or the JSE. In particular, the applicants contended that the description included persons who entered into a contract to acquire ordinary shares in BHP Ltd through a trade on Chi-X Australia (now known as Cboe Australia) (Chi-X). BHP Ltd contended that the description only covers persons who, during the relevant period, entered into contracts to acquire ordinary shares in BHP Ltd or BHP Plc through trading on the ASX, the LSE or the JSE. Moshinsky J concluded that the interpretation advanced by BHP Ltd was correct (Impiombato No 4 at [30]).
8. On 17 November 2023, Moshinsky J made an order extending until 24 November 2023 the date for filing any application for leave to appeal from the judgment in Impiombato No 4. On 24 November 2023, the applicants filed an application for leave to appeal (which has been given the file number VID 989 of 2023). The applicants also sought the adjournment of the hearing of the application for leave to appeal pending the determination of an application to amend the originating application and statement of claim to vary the group definition.
9. On 5 December 2023, the applicants filed the foreshadowed application to amend the originating application and statement of claim. The purpose of the proposed amendments was to bring the group definition into line with the definition propounded by the applicants, and to make certain consequential amendments. Controversially, the applicants also sought an order that the amendments take effect on and from the commencement of the proceeding, being 31 May 2018. That order would overcome the operation of applicable limitation periods under the Corporations Act and the ASIC Act that would otherwise be a bar to financial relief.
10. The application for leave to amend was heard by Murphy J on 25 March 2024. BHP Ltd did not oppose the grant of leave to amend, but opposed the making of an order that the amendments take effect on and from 31 May 2018. On 6 June 2024, Murphy J granted the applicants leave to amend the originating application and statement of claim, and also ordered that the amendments take effect on and from 31 May 2018, with reasons published in Impiombato v BHP Group Limited (No 5) [2024] FCA 591 (Impiombato No 5).
11. On 19 June 2024, BHP Ltd applied for leave to appeal from the judgment in Impiombato No 5 (which application has been given the file number VID 553 of 2024).
12. On 30 July 2024, orders were made pursuant to s 24(1A) of the Federal Court of Australia Act 1976 (Cth) (FCA Act) granting the applicants leave to appeal from the judgment in Impiombato No 4 and granting BHP Ltd leave to appeal from the judgment in Impiombato No 5.
13. The principles concerning an appeal under s 24 of the FCA Act are well known. In short, an appeal is by way of rehearing, but it is a jurisdiction for the correction of error: Branir Pty Ltd v Owston Nominees (No 2) Pty Ltd (2001) 117 FCR 424 at [21]-[22] (Allsop J). Where the decision appealed from involves the exercise of discretion by the primary judge, the Court will not interfere unless an error of the kind referred to in House v The King (1936) 55 CLR 499 (House v The King) at 504-5 is shown to have been made in the exercise of the discretion.
14. While the decisions in Impiombato No 4 and Impiombato No 5 are interlocutory, they are not merely decisions on matters of practice and procedure in respect of which appellate interference is kept on a "tight rein" (as observed by Lindgren J in Bright v Femcare Ltd [2002] FCAFC 243; 195 ALR 574 at [2]). The decision in Impiombato No 4 concerns the identification of the persons on whose behalf the proceeding has been brought. The decision in Impiombato No 5 concerns the date from which the amendments to the group definition take effect, which affects the operation of applicable limitation periods. Both decisions have a significant effect on the rights and interests of the parties to the proceeding and group members.
15. The applicants' appeal from the judgment in Impiombato No 4 raises a narrow issue: whether Moshinsky J's interpretation of the group definition in the originating application and statement of claim is correct. While the supplementary notice of appeal states six grounds of appeal, the grounds largely record the arguments advanced by the applicants for their preferred interpretation of the group definition. For the reasons given below, Moshinsky J's interpretation of the group definition in the originating application and statement of claim is correct.
16. BHP Ltd's appeal from the judgment in Impiombato No 5 also raises a relatively narrow issue: whether there was error in the discretionary judgment of Murphy J that the amendments to the originating application and statement of claim should take effect from the commencement of the proceeding. Respectfully, for the reasons given below, his Honour's discretionary decision is based on material errors of fact and should be set aside. In the course of argument on the appeal, it became apparent that the amendments have two effects which should be separately considered. The first effect is to broaden the group definition to include persons who, prior to the amendment, would not have been group members. They are persons who acquired ordinary shares in BHP Ltd or BHP Plc during the relevant period only on a trading platform or exchange other than the ASX, LSE or JSE (such as Chi-X). Applying the principles stated by the Full Court in Ethicon Sàrl v Gill (2018) 264 FCR 394 (Ethicon Sàrl), that amendment to the group definition should take effect from the date of the amendments. The second effect is to broaden the claims made on behalf of existing group members to include claims in respect of the acquisition of ordinary shares in BHP Ltd or BHP Plc during the relevant period on trading platforms other than the ASX, LSE or JSE (such as Chi-X). Applying established principles, that amendment should take effect from the commencement of the proceeding as the effect of the amendment is to add a claim that arises out of substantially similar facts to the existing claims made in the proceeding.

The group definition

1. In this proceeding, and for the purposes of s 33H of the FCA Act, the applicants described the group members to whom the proceeding relates in both the originating application (being the consolidated originating application dated 16 August 2019) and the statement of claim (being the amended consolidated statement of claim dated 7 September 2020).
2. The originating application contained the following description: The Group Members to whom this proceeding relates are all persons who or which:
3. during the Relevant Period entered into a contract (whether themselves or by an agent or trustee) to acquire an interest in: (a) BHP ASX Shares; and/or (b) BHP LSE Shares; and/or (c) BHP JSE Shares;
4. are not within the classes of excluded persons referred to in paragraph 3(b) of the consolidated statement of claim; and
5. are alleged to have suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in the consolidated statement of claim.
6. The originating application also contained the following notation: NOTE: Capitalised terms have the same meaning as in the consolidated statement of claim unless otherwise defined herein.
7. None of the capitalised terms "Relevant Period", "BHP ASX Shares", BHP LSE Shares" or "BHP JSE Shares" were defined in the originating application. Accordingly, the definitions are to be found in the statement of claim.
8. The statement of claim did not merely define the foregoing capitalised terms. The statement of claim contained a stand-alone description of group members as follows: The Joint Applicants and the persons they represent (the Group Members) are all persons who or which: (a) during the period from 8 August 2012 to the close of trade on 9 November 2015 inclusive (Relevant Period) entered into a contract (whether themselves or by an agent or trustee) to acquire an interest in fully paid up ordinary shares in: (i) the Respondent, formerly BHP Billiton Limited (BHP Ltd), on the Australian Securities Exchange (ASX), a financial market operated by ASX Limited (the BHP ASX Shares); (ii) BHP Group Plc, formerly BHP Billiton Plc (BHP Plc), a company registered in England and Wales, on the London Stock Exchange (LSE), a financial market operated by the London Stock Exchange Group Plc (the BHP LSE Shares); and/or (iii) BHP Plc on the Johannesburg Stock Exchange (JSE), a financial market operated by the Johannesburg Stock Exchange Limited (the BHP JSE Shares); (b) were not during any part of the Relevant Period, and are not, any of the following: (i) a director or officer or a close associate (as defined by s 9 of the Corporations Act) of BHP Ltd; (ii) a related party (as defined by s 228 of the Corporations Act) of BHP Ltd; (iii) a related body corporate (as defined by s 50 of the Corporations Act) of BHP Ltd; (iv) an associated entity (as defined by s 50AAA of the Corporations Act) of BHP Ltd; (v) a Justice, Registrar, District Registrar or Deputy District Registrar of the Federal Court of Australia or the High Court of Australia; or (vi) an officer or employee of Maurice Blackburn Lawyers or Phi Finney McDonald, or a legal representative engaged by Maurice Blackburn Lawyers or Phi Finney McDonald in this proceeding; and (c) are alleged to have suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in this statement of claim.

Reasons of the primary judge

1. The primary judge described the issue in dispute between the parties as follows (at [4]): The issue of interpretation between the parties is whether the group member definition covers persons who, during the Relevant Period, entered into contracts to acquire shares in the respondent (BHP Ltd) or BHP Group Plc (formerly BHP Billiton Plc) (BHP Plc) on trading platforms other than the ASX, the LSE or the JSE. For example, is a person who entered into a contract to acquire shares in BHP Ltd through a trade on Chi-X Australia (now known as Cboe Australia) (Chi-X) within the group member definition? BHP Ltd contends that such persons are not within the group member definition; the applicants contend that such persons are within the group member definition.
2. His Honour recorded the evidence that was adduced by the parties on the application. The applicant read two affidavits of Andrew Watson dated 15 and 27 October 2023. Mr Watson was, at that time, a principal of Maurice Blackburn Lawyers, one of the two firms of solicitors representing the applicants. On 13 November 2023, Mr Watson was appointed as a judge of the Supreme Court of Victoria. In these reasons, it is appropriate to refer to Mr Watson by his title at the time he swore his affidavit, rather than by reference to his current title of Justice Watson. No disrespect is intended by doing so.
3. BHP Ltd read two affidavits of Christine Tran dated 12 and 19 October 2023. Ms Tran is a partner of Herbert Smith Freehills, the solicitors for BHP Ltd.
4. Although his Honour concluded that the interpretation of the group definition should be approached objectively having regard to both the text and the context of the definition (at [22] and [25]), his Honour also made factual findings based on the evidence adduced by the parties. The factual findings concerned a range of matters including BHP's dual listed company structure, the listing of the ordinary shares in BHP Ltd on the ASX and the ordinary shares in BHP Plc on the LSE and the JSE, the ability of shareholders to trade those shares on those exchanges and on other exchanges such as Chi-X, and the manner in which shares traded on Chi-X were cleared and settled. The parties did not object to his Honour's reliance on that evidence on the issue of interpretation, and did not challenge that reliance on this appeal. The relevance of such evidence in this context is discussed further below.
5. Based on the affidavits of Ms Tran, his Honour found (at [10] and [11]) that, during the relevant period:
6. BHP operated under a dual listed company structure with two parent companies, BHP Ltd and BHP Plc.
7. BHP Ltd was incorporated in Australia and BHP Plc was incorporated in the UK.
8. BHP Ltd had a primary listing on the ASX in Australia (it was admitted to the official list on the ASX) and its ordinary shares were admitted for quotation and trading on the ASX, and on other exchanges.
9. BHP Plc had a premium listing on the UK Listing Authority's Official List and its ordinary shares were admitted to trading on the LSE in the United Kingdom, and a secondary listing on the JSE in South Africa, and its ordinary shares were available for trading on the LSE and JSE respectively, and on other exchanges.
10. Ordinary shares in BHP Ltd were maintained on a share register that records the identity of the registered shareholders and buy/sell trading activities of those shareholders. The shares could be and were traded on the ASX, being the primary trading platform or exchange, and could be and were traded on other trading platforms or exchanges, sometimes referred to as secondary trading platforms, such as the exchange operated by Cboe Australia Pty Ltd (formerly Chi-X Australia).
11. Ordinary shares in BHP Plc were maintained on a share register (separate from the share register of BHP Ltd) that records the identity of the registered shareholders and buy/sell trading activities of those shareholders. The shares could be and were traded on the LSE, being the primary trading platform or exchange, and could be and were traded on the JSE, being the secondary trading platform or exchange, and could be and were traded on other trading platforms or exchanges, such as the exchanges operated by BATS Chi-X Europe.
12. There was also a separate (secondary) register for trades in BHP Plc that occurred on the JSE, and those trades were reflected on the (South African) share register of BHP Plc.
13. Trades in ordinary shares in BHP Ltd and BHP Plc were reflected on the respective share registers, but (other than as set out in para (g) above) the share registers do not record the platform upon which the trades occurred.
14. Based on the affidavits of Mr Watson, his Honour found (at [13] and [14]) that, during the relevant period:
15. Chi-X was an alternative trading platform to the ASX for some shares in ASX-listed entities as well as some other financial products. Shares purchased through Chi-X could be sold on the ASX and vice versa, provided that the stock was available on both platforms. Unlike the ASX, Chi-X did not maintain an official list to which corporations could be or were admitted. Rather, Chi-X operated an alternate facility through which Australian securities could be and were traded. No other platform offered this facility during the relevant period. Ordinary shares in BHP Ltd could be, and were, traded on the Chi-X trading platform. However, BHP Ltd was not "listed" on Chi-X, in the terminology of Australian corporations law.
16. Most online brokers enabled investors to trade Australian securities on Chi-X, including CommSec, NABTrade, Stake, Selfwealth, CMC Markets and Superhero. Generally, when executing a trade through these brokers, an investor would not specify whether the trade should be executed on Chi-X or the ASX. Rather, that was left to the broker's discretion as informed by their duty to comply with the best execution obligations set out in the ASIC Market Integrity Rules.
17. Clearing and settlement of trades was conducted by the ASX through its Clearing House Electronic Subregister System (CHESS), which combined settlement services with an electronic CHESS subregister that recorded the ownership details of Australian securities. Shareholdings registered on the CHESS subregister were communicated to the issuer sponsored subregister (in the case of BHP Ltd, its subregister is maintained by ComputerShare Pty Ltd) and vice versa, such that both subregisters contained a complete and consistent record of members and their shareholdings.
18. Clearing and settlement of trades executed on Chi-X were facilitated by the ASX and would settle on an investor's CHESS HIN (Holder Identification Number) or directly with share registries in an identical fashion to those traded directly on the ASX. The ASX's Trade Acceptance Service and Settlement Facilitation Service operated to provide an Approved Market Operator (AMO), such as Chi-X, with centralised clearing and settlement services in an identical fashion to trades executed on ASX's cash equity market trading platform (known as ASX Trade).
19. Specifically, ASX Clear, a wholly-owned subsidiary of ASX Ltd, provided clearing services to ASX participants. Chi-X, as an AMO, was entitled to have its trades accepted for clearing by ASX Clear on the same basis as those executed on ASX Trade. For both ASX Trade and Chi-X, ASX Clear acted as a central counterparty (CCP) for the trading of shares, warrants and exchange-traded funds. As a CCP, ASX Clear became liable for the completion of all clear transactions on the relevant market. This occurred through a process of novation whereby the original market contract between the trading participant (being a broker authorised on the ASX's market) representing the buyer and the trading participant representing the seller was discharged and replaced with two new contracts: one between ASX Clear and the clearing participant (being a broker authorised to clear trades through the ASX Clearing House) representing the buyer, and the other between ASX Clear and the clearing participant representing the seller. In this way, ASX Clear became the counterparty assuming the credit risk.
20. As with trades executed on ASX Trade, trades executed on Chi-X were submitted to ASX Clear for registration. Once accepted by ASX Clear, by way of novation, each cash market trade was replaced with a cash market CCP transaction between each participant and ASX Clear. Where the cash market trade was cleared on both sides by the same clearing participant, there was no need for novation and the participant received notification of the trade. Accordingly, a buyer's interest in a share acquired through a Chi-X placed trade was indistinguishable from one placed directly through the ASX Trade.
21. The primary judge observed (at [21]) that, in the present case, both the originating application and the statement of claim contained a group definition, expressed in different terms. His Honour noted that the definition appearing in the originating application was only an abbreviated definition in that it used expressions that were defined in the statement of claim and did not contain the same level of detail as the definition in the statement of claim. The statement of claim, on the other hand, contained a complete definition. In those circumstances, his Honour reasoned that it was necessary to focus on the definition in the statement of claim.
22. His Honour further observed that the text of the group definition in the statement of claim favoured BHP Ltd's interpretation (at [23]). Paragraph 3(a)(i) stated that group members are persons who, during the relevant period, "entered into a contract … to acquire an interest in … ordinary shares in … the Respondent … on the Australian Securities Exchange". His Honour considered that the natural way to read this is that the shares were acquired on the ASX (that is, through trading on the ASX). In other words, the word "on" qualified the acquisition. His Honour considered that it would be strained to read the definition in the manner propounded by the applicants: that the phrase "on the Australian Securities Exchange" only qualified the phrase "ordinary shares in … the Respondent"; in other words, the definition conveyed that group members are persons who entered into a contract (on any platform or in any circumstances) to acquire a particular category type of shares, being ordinary shares in BHP Ltd that were listed on the ASX. His Honour reached the same conclusion with respect to paras 3(a)(ii) and (iii) concerning the shares in BHP Plc listed on the LSE and JSE.
23. The primary judge next observed that the context of the group definition in the statement of claim includes the rest of the pleading (at [24]). In his Honour's view, a consideration of the balance of the pleading supported BHP Ltd's interpretation. In that regard, his Honour noted the following matters: the pleading contained a definition of the BHP ASX Share Market (in para 5(c)), the BHP LSE Share Market (in para 8(a)) and the BHP JSE Share Market (in para 8(b)); those markets then form the basis for a substantial part of the causation pleading in section L of the statement of claim (paras 68-80); and, in broad terms, it is alleged that the alleged contraventions of the Corporations Act and ASIC Act caused the price at which the relevant shares traded on the ASX, the LSE and the JSE to be higher than their true value or the market price that would have prevailed but for the contraventions. His Honour concluded that those allegations appear to be predicated on group members having purchased their shares on one of those exchanges, as no other platforms were pleaded or referred to.
24. His Honour briefly addressed, and rejected, a number of arguments advanced by the applicants:
25. First, insofar as the applicants contended that it was always their intention to cover all persons who acquired an interest in shares in BHP Ltd or BHP Plc during the relevant period, his Honour considered that the issue of interpretation must be approached objectively rather than subjectively (at [25]).
26. Second, insofar as the applicants submitted that it would make no sense to carve out persons who acquired their shares on other trading platforms, his Honour did not accept the submission. His Honour reasoned that, having regard to the causation pleading referred to above, there is a logic to defining the class by reference to the acquisition of the relevant shares on the ASX, the LSE or the JSE (at [26]).
27. Third, insofar as the applicants submitted that BHP Ltd had conducted the proceeding on the basis that the group definition included persons who acquired shares on other platforms, his Honour was not persuaded that that was correct. His Honour observed that some of the materials filed by BHP Ltd mirrored the group definition in the statement of claim (at [27]).
28. Fourth, insofar as the applicants contended that their interpretation was to be preferred because it avoided a multiplicity of proceedings, his Honour considered that while that is a general objective of the representative proceeding provisions, it is not of assistance in resolving the issue of interpretation (at [28]).
29. Fifth, insofar as the applicants relied on the fact that clearing and settlement of trades executed on Chi-X were facilitated by the ASX in the way described above, his Honour did not consider that to assist the applicants' position. His Honour considered that it would be inapt to describe a trade executed on Chi-X that was cleared and settled by the ASX (or its subsidiaries) as an acquisition "on the ASX". It is, rather, aptly described as an acquisition "on Chi-X" (at [29]).
30. In light of the foregoing, the primary judge considered the correct interpretation of the group definition to be that it covered persons who, during the relevant period, entered into a contract to acquire an interest in fully paid-up ordinary shares in BHP Ltd through trading on the ASX and/or fully paid-up ordinary shares in BHP Plc through trading on the LSE or the JSE (at [30]).

Applicants' grounds of appeal and submissions

1. The applicants' supplementary notice of appeal stated the following six grounds of appeal:
2. The primary judge erred in finding that the definition of Group Members in the consolidated originating application dated 16 August 2019 (COA) was only an abbreviated definition so that it was necessary to focus on the definition in the statement of claim (J [21]).
3. The primary judge ought to have found, by reference to s 33H of the Federal Court of Australia Act 1976 (Cth), that the COA (read with any relevant definitions incorporated from the statement of claim) described or otherwise identified the group members to whom the proceeding relates.
4. The primary judge ought to have found that the group members to whom the proceeding relates are the persons described in the COA, being all persons who, during the Relevant Period, entered into a contract to acquire an interest in fully paid-up ordinary shares in BHP Ltd quoted on the ASX and/or BHP Plc quoted or listed on the LSE or the JSE.
5. The primary judge acted on a wrong principle and/or failed to take into account a relevant consideration in preferring a construction of the description of the group members that was contrary to or in tension with the provisions and/or objects of Pt IVA of the Federal Court of Australia Act 1976 (Cth) when an alternative construction consistent with those provisions and/or objects was open on the description (J [28]).
6. The primary judge erred in finding that a trade executed on Chi-X Australia that is cleared and settled by the ASX (or its subsidiaries) is not an acquisition of shares "on the ASX" for the purpose of the description of the group members (J [29]).
7. The primary judge acted on a wrong principle and/or failed to take into account a relevant consideration in determining the definition of the group members without having regard to the intention of the applicants that the proceeding be brought on behalf of all persons who acquired an interest in ordinary shares in BHP Ltd and BHP Plc during the Relevant Period (J [25]) and/or failing to find that the Respondent had at all times acted on the basis that the proceeding had been brought on behalf of all such persons (J [27]).
8. The applicants' submissions were not organised by reference to the grounds of appeal. As the respondent did not suggest that the submissions went beyond the grounds of appeal, it is convenient to focus on the applicants' submissions rather than the grounds of appeal.
9. At least in one respect, however, the applicants' submissions contradicted or narrowed the grounds of appeal. By ground 6, the applicants contended that the primary judge acted on a wrong principle and/or failed to take into account a relevant consideration in determining the definition of the group members without having regard to the intention of the applicants. In their written submissions, however, the applicants accepted that the group definition should be interpreted objectively, not subjectively, stating: The primary judge held, and the appellants do not dispute, that the interpretation of the group definition should be approached objectively.
10. In their submissions, the applicants contended that the primary judge erred for the following four reasons.

Textual and contextual arguments

1. The applicant's first submission was that, on its true construction, the group definition in the originating application and the statement of claim included all persons who acquired shares in BHP Ltd and/or BHP Plc during the relevant period, and was not limited to persons who acquired shares "through trading" on the ASX, LSE or JSE. In support of that submission, the applicants relied on a series of textual and contextual arguments.
2. The applicants submitted that the primary judge failed to take the group definition in the originating application as the starting point. The applicants argued that the definition in the originating application extended without limitation to all persons who, during the relevant period, "entered into a contract … to acquire an interest in" "BHP ASX Shares", "BHP LSE Shares" or "BHP JSE Shares". The use of the preposition "in" made the acquisition of an interest "in" the relevant shares the essential condition of group membership, without imposing any further requirement that those shares be acquired through particular platforms or exchanges.
3. The applicants accepted that the expressions "BHP ASX Shares", "BHP LSE Shares" and "BHP JSE Shares" used in the originating application were defined in para 3(a) of the statement of claim. Using "BHP ASX Shares" as the exemplar, the applicants argued that the defined expressions should be understood as referring to "fully paid up ordinary shares in the Respondent … on the Australian Securities Exchange (ASX), a financial market operated by ASX Limited". The applicants argued that, in this context, the word "on" in para 3(a)(i) of the statement of claim was used in the sense of BHP Ltd being "listed on" the ASX or its ordinary shares being "quoted on" or "listed on" the ASX. During the relevant period, BHP Ltd was listed on the ASX and its ordinary shares were a class of securities admitted for quotation on the ASX. Although shares in BHP Ltd could be traded on secondary platforms - for example, on Chi-X - those trades were still in shares quoted on the ASX in a company listed on the ASX.
4. The applicants further submitted that there are a number of contextual indications in the statement of claim supporting the conclusion that the expressions "BHP ASX Shares", "BHP LSE Shares" and "BHP JSE Shares" defined the relevant shares, not the act of acquiring shares. Those indications include paras 5(c)(i), 5(c)(v), 68(b) and 69, each of which referred to BHP ASX Shares traded, acquired or sold on the ASX.

Purposive arguments

1. The applicants' second argument was that any ambiguity in the group definition ought to have been resolved by adopting the applicants' broader construction consistent with the objective purpose of the pleading and the objects and requirements of the representative proceeding regime in Part IVA of the FCA Act.
2. The applicants submitted that there was no reason to exclude from the "class" persons who acquired shares in BHP Ltd or BHP Plc through trading platforms or exchanges other than the ASX, LSE and JSE. In that regard, the applicants' placed reliance on the principles of construction applicable to commercial contracts, specifically that the court should give a commercial contract a businesslike interpretation on the assumption "that the parties ... intended to produce a commercial result". As to the application of principles of contractual construction to the interpretation of pleadings, the applicants placed reliance on a statement of Ipp JA in Ingot Capital Investments Pty Ltd v Macquarie Equity Capital Markets Ltd (2008) 73 NSWLR 653 at [380]-[381] and submitted that, in Bauer Consumer Media Ltd v Evergreen Television Pty Ltd [2019] FCAFC 71; 367 ALR 393, Greenwood J (at [73]-[79] and [141]-[142]) and Burley J (at [254]-[267]) adopted an interpretative approach analogous to contractual interpretation. The applicants did not otherwise explain why principles of construction applicable to commercial contracts have any relevance to the interpretation of an originating application and a statement of claim.
3. The applicants submitted that, if there were any ambiguity in the expression of the group definition, the objects of Pt IVA required the primary judge to adopt whatever reasonably open definition would best avoid a multiplicity of proceedings by covering as many potential group members as possible. In that regard, the applicants referred to the observation of Gordon, Edelman and Steward JJ in BHP Group Ltd v Impiombato (2022) 276 CLR 611 (Impiombato HC) at [74] that the purposes of Pt IVA include "the creation of an efficient and comprehensive mechanism for the determination of similar claims", and a construction that "would create a risk of a multitude of parallel proceedings or actions" would be "directly contrary" to that purpose.
4. The applicants further submitted that the interpretation of a group definition should not be approached in an overly technical or pedantic way, but having regard to the function that it is intended to perform under Part IVA, referring to J Wisbey & Associates Pty Ltd v UBS AG [2021] FCA 36 at [13] (Beach J) and Petrusevski v Bulldogs Rugby League Club Ltd [2003] FCA 61 (Petrusevski) at [20]-[22] (Sackville J). For a group definition to comply with the requirements of s 33H, it must be possible for a person to ascertain whether they are a group member. The applicants argued that, in this case, reading a condition into the group definition that the shares had to be acquired through trading on the ASX, LSE or JSE would make it impractical, and potentially impossible, for some persons to determine whether they are group members.
5. The applicants also criticised the primary judge's finding (at [27]) that it was not clear (in other words, it was not established) that BHP Ltd had conducted the proceeding on the basis that the group definition included persons who acquired shares on other platforms. Ultimately, the criticism rose no higher than an assertion that BHP Ltd had failed to establish that it had conducted the proceeding on the basis that group members were persons who had acquired shares on the ASX, LSE or JSE.

Primacy of the originating application

1. The applicants' third argument was that, if the statement of claim contained a narrower group definition, the primary judge should have given primacy to the definition in the originating application in accordance with s 33H of the FCA Act. The applicants submitted that the primary judge was wrong to conclude that the definition in the originating application was merely an "abbreviated definition" subordinate to the "complete definition" in the statement of claim. The applicants argued that the primacy of the originating application arises from its status as the document by which an applicant commences a Part IVA representative proceeding and moves the court to grant the relief sought. The applicants further submitted that, as s 33H(1) makes plain, a statement of claim is a document filed "in support of" an originating application and therefore subordinate to it.
2. The applicants referred to the dissenting remarks of Barwick CJ and McTiernan J in Renowden v McMullin (1970) 123 CLR 584 (Renowden) at 596 as authority in support of the primacy of an originating process in marking out the boundaries of an applicant's claim and resolving any ambiguity in an accompanying statement of claim. The proceeding was commenced by writ which bore a general indorsement alleging breach of contract and breach of duty of care. A statement of claim was subsequently delivered which made no claim based on breach of contract. The plaintiff sought leave to amend the statement of claim to introduce a claim based on breach of contract. In holding that the amendment should be allowed, Barwick CJ and McTiernan J (in dissent) explained (at 595) that "the indorsement marks out the perimeter or range of the area within which the plaintiff may express his claim in a formal fashion in his statement of claim whether as originally filed or as sought to be amended". The applicants also relied on the further remark of Barwick CJ and McTiernan J (at 596) that: Possibly, however, where there is ambiguity in the statement of claim the indorsement may serve to throw light upon the meaning of the statement of claim or of expressions in it.
3. The applicants submitted that, by parity of reasoning, the originating application defines the perimeter or range of the claims that are the subject of the proceeding, and it may serve to throw light upon any ambiguity in the statement of claim, including (as relevant here) with respect to the expression of the group definition.

An acquisition of shares on Chi-X is an acquisition on the ASX

1. The applicants' fourth argument is that, even if the primary judge's interpretation of the group definition is correct, it does not follow that persons who only acquired shares in the BHP entities through trading on secondary trading platforms are excluded from the group definition because such trades still qualify as acquisitions "on the ASX" (or the LSE or JSE). In support of that submission, the applicants relied on the evidence establishing that share trades on Chi-X are cleared and settled through the ASX settlement processes, as described in the factual findings made by the primary judge.

Proper approach to interpretation

1. It is convenient to commence with the proper approach to interpretation. The applicable principles governing the task of interpretating the meaning of written words depend upon the legal context. The principles governing the interpretation of statutes are not the same as the principles governing the interpretation of contracts, although there is overlap.
2. The present case involves the interpretation of an originating application and a statement of claim. To state the obvious, those documents are neither statutes nor contracts. As explained by the High Court in Dare v Pulham (1982) 148 CLR 658 at 664, the purpose of such documents is to ensure procedural fairness in the conduct of a proceeding: to furnish a statement of the case sufficiently clear to allow the other party a fair opportunity to meet it, and to define the issues for decision in the litigation and thereby enable the relevance and admissibility of evidence to be determined at the trial. In resolving disputes over the meaning of an originating application or a pleading, a court will ordinarily be guided by the objective meaning of the words, taking account of the text and context. However, in determining the issues to be resolved in a proceeding, or whether to allow an amendment to an originating application or a pleading, a court may also take into account the manner in which the parties have conducted the proceedings. As observed by Isaacs and Rich JJ in Gould v Mount Oxide Mines Ltd (1916) 22 CLR 490 at 517-518: Undoubtedly, as a general rule of fair play, and one resting on the fundamental principle that no man ought to be put to loss without having a proper opportunity of meeting the case against him, pleadings should state with sufficient clearness the case of the party whose averments they are. That is their function. Their function is discharged when the case is presented with reasonable clearness. Any want of clearness can be cured by amendment or particulars. But pleadings are only a means to an end, and if the parties in fighting their legal battles choose to restrict them, or to enlarge them, or to disregard them and meet each other on issues fairly fought out, it is impossible for them to hark back to the pleadings and treat them as governing the area of contest. … There are qualifications, no doubt, and each case must depend for the proper application of the principle upon its own facts.
3. The specific issue of interpretation in this case concerns the description of group members contained in the originating application and statement of claim. The inclusion of the description is a statutory requirement in Pt IVA of the FCA Act. Section 33H of the FCA Act stipulates as follows: 33H Originating process (1) An application commencing a representative proceeding, or a document filed in support of such an application, must, in addition to any other matters required to be included: (a) describe or otherwise identify the group members to whom the proceeding relates; and (b) specify the nature of the claims made on behalf of the group members and the relief claimed; and (c) specify the questions of law or fact common to the claims of the group members. (2) In describing or otherwise identifying group members for the purposes of subsection (1), it is not necessary to name, or specify the number of, the group members.
4. It can be seen that s 33H requires that the originating application commencing a representative proceeding, or a supporting document, must include three things. First, it must include a description of the group members to whom the proceeding relates (or otherwise identify them). Second, it must specify the nature of the claims made on behalf of the group members and the relief claimed. Third, it must specify the questions of law or fact common to the claims of the group members.
5. The requirements of s 33H are fundamental to the operation of Part IVA of the FCA Act. First, s 33H operates to ensure that the Court can assess, at the outset, whether the specified pre-conditions for the commencement of a representative proceeding, contained in s 33C, are present: Wong v Silkfield Pty Ltd (1999) 199 CLR 255 at [8]; Ethicon Sàrl at [7]. Second, s 33H operates to identify both the class of group members who are represented in the proceeding, and the claims made on behalf of the group members, so that group members can decide whether they wish to opt out of the proceeding in accordance with the procedures governed by s 33J: Petrusevski at [20]. Third, s 33H operates so as to define the claims of group members for which the running of any limitation period is suspended under s 33ZE.
6. It follows that certainty as to "class composition", the description of group members, is fundamental to the operation of Pt IVA, as observed by the Full Court in Ethicon Sàrl at [38]. As has been said on many occasions, it must be possible for persons who may be within the represented group to ascertain from the originating process or pleadings whether they are in fact group members: Petrusevski at [20]; Dyczynski v Gibson (2020) 280 FCR 583 at [170] (Murphy and Colvin JJ) and [335] (Lee J).
7. Having regard to the important function of the description of group members within a representative proceeding, the interpretation of the description is not solely a matter for the parties to the proceeding. The description of group members in an originating application or pleading is not a matter that the parties can freely disregard and enlarge by their conduct of the proceeding (unlike issues raised in ordinary inter partes litigation). The description of group members affects the interests of persons who are not parties to the litigation. Such persons may act on the assumption that they are within the description, or may act on the assumption that they are not within the description. In so acting, such persons are entitled to expect that the description of group members is as stated in the originating application or pleading. Ordinarily, such persons cannot be expected to be aware of the manner in which the parties to the litigation have conducted the proceeding, nor the subjective beliefs of the parties with respect to the meaning of the group definition.
8. Those considerations confirm the appropriateness of applying an objective approach to the interpretation of a group definition. It may be that, in some circumstances, the conduct of the parties in the course of a representative proceeding may bear upon the interpretation of a group definition, or be relevant in the exercise of the discretion to allow an amendment. However, a compelling reason would need to be shown to depart from an objective approach. It follows that, in the present case, we respectfully agree with the conclusion of the primary judge (at [25]) that the issue of interpretation should be approached objectively (in other words, looking at the words used in context) rather than subjectively.
9. The applicants' arguments based on the "primacy" of the originating application over the statement of claim are unsound. The reasons of Barwick CJ and McTiernan J in Renowden, even in dissent, do not support the contention of primacy. The reasons of the majority in Renowden (expressed in the reasons of Owen J, with whom Kitto and Menzies JJ agreed) were that regard must be had to the statement of claim, not the writ, in determining the claims that the plaintiff wished to litigate (at 608). Under the Federal Court Rules 2011 (Cth) (FC Rules), the two documents serve different functions and have different contents. The filing of an originating application initiates the proceeding. In addition to the names of the parties, the originating application need only state the relief claimed in the proceeding (see r 8.03). The FC Rules contemplate that an originating application will be accompanied by another document which states the claim that is made (see r 8.05). Where the relief sought includes damages, the accompanying document must be a statement of claim (or an alternative accompanying document specified by the Chief Justice in a practice note). Section 33H is neutral as to whether the description of group members is contained in the originating application or the statement of claim, stipulating that the description may be included in an "application commencing a representative proceeding, or a document filed in support of such an application".
10. Finally, reference should be made to the evidence adduced on the question of the interpretation of the group definition. It follows from the foregoing that the evidence of the subjective intentions of the applicants and their solicitors is irrelevant to the question of interpretation, as concluded by the primary judge (at [25]). However, in the context of the interpretation of both statutes and contracts, a court will allow evidence to be given as to the technical or customary usage of words and phrases, where such technical or customary usage is relevant to the statutory or contractual context. Ultimately, a court must determine whether the written words and phrases in question have been used in accordance with the asserted technical or customary usage or in accordance with their ordinary meaning. Further, in the context of the interpretation of contracts, a court will allow evidence of surrounding circumstances, known to both parties, if the language of the contract is ambiguous or susceptible of more than one meaning: Codelfa Construction Pty Ltd v State Rail Authority of New South Wales (1982) 149 CLR 337 at 352 (Mason J, as his Honour then was). Broadly, the same considerations can be applied in the interpretation of pleadings. Evidence may be used to inform the court of surrounding circumstances in which the claims arise and, where relevant, of the technical or customary usage of words and phrases contained within a pleading. It is nevertheless appropriate to express some caution with respect to the receipt of evidence on the question of the interpretation of a group definition. As discussed above, persons should be able to ascertain from the originating process or pleading itself whether they are group members. In receiving evidence of technical or customary usage of words and phrases, or of surrounding circumstances, for the purpose of interpreting a group definition, it is appropriate for the court to consider whether a person who might be within the group definition would be expected to have knowledge of the matters that are the subject of the evidence. The more obscure or technical the evidence, the less relevant it will be to the task of interpretation.
11. In the present case, the parties adduced evidence with respect to the listing and quotation of BHP Ltd and BHP Plc shares on the ASX, LSE and JSE, the ability of shareholders to trade those shares on those exchanges and on other exchanges such as Chi-X, and the manner in which shares traded on Chi-X were cleared and settled. The primary judge made factual findings on the basis of that evidence and took those facts into account in the interpretation of the group definition. Neither party objected to that course, nor challenged the factual findings made.

The originating application and statement of claim

1. It is necessary to read the group definition in the context of the claims made by the applicants. It is therefore necessary to have regard to the entirety of the originating application and the statement of claim. The procedural history of those documents also forms part of the relevant context in which to interpret the group definition. The procedural history is revealing.

Commencement of VID 649 of 2018

1. On 31 May 2018, Mr Impiombato filed a representative proceeding against BHP Ltd (then called BHP Billiton Limited), which was given the proceeding number VID 649 of 2018. Mr Impiombato was represented by Phi Finney McDonald and the originating process was prepared by Benjamin Phi of that firm. The statement of claim was prepared by counsel and certified by Mr Phi.
2. In accordance with s 33H(1)(a) of the FCA Act, the originating application relevantly described the group members to whom the proceeding related as follows: The group members to whom this proceeding relates are persons who: (a) During the period from 21 October 2013 until the close of trade on 9 November 2015 inclusive (Relevant Period), acquired an interest in: (i) fully paid ordinary shares in the Respondent (BHP Limited) on the Australian Securities Exchange (ASX) (the ASX Group Members); and/or (ii) fully paid ordinary shares in BHP Plc a company registered in England and Wales, on the London Stock Exchange (the LSE Group Members); and/or (iii) fully paid ordinary shares in BHP Plc on the Johannesburg Stock Exchange (the JSE Group Members); (b) suffered loss or damage by reason of the conduct of the Respondent alleged in the Statement of Claim; …
3. There is no ambiguity in that group definition. The ordinary grammatical meaning is that group members are persons who, during the period stated, acquired an interest in ordinary shares in BHP Ltd on the ASX or acquired ordinary shares in BHP Plc on the LSE or the JSE, and suffered loss by reason of the alleged wrongful conduct of BHP Ltd. The phrases that commence with the word "on" qualify the verb "acquired".
4. The group definition in the originating application was largely replicated in para 3 of the statement of claim, which was relevantly as follows: The Applicant and the persons he represents (Group Members) are persons who: (a) during the period from 21 October 2013 until the close of trade on 9 November 2015 inclusive (Relevant Period), acquired an interest in: (i) fully paid ordinary shares in the Respondent (BHP Limited) on the Australian Securities Exchange (ASX), a financial market operated by the Australian Securities Exchange Limited (ASX Limited) (the ASX Group Members); and/or (ii) fully paid ordinary shares in BHP Billiton Plc (BHP Plc), a company registered in England and Wales, on the London Stock Exchange (LSE), a financial market operated by the London Stock Exchange Group Plc (the LSE Group Members); and/or (iii) fully paid ordinary shares in BHP Pie on the Johannesburg Stock Exchange (JSE), a financial market operated by the Johannesburg Stock Exchange Limited (the JSE Group Members); and … (c) are alleged to have suffered loss and damage by or resulting from the conduct of the Respondent alleged below.
5. It can be seen that, in the definition in the statement of claim, a description of each exchange was added. For example, the ASX was described as a financial market operated by ASX Limited. The addition did not, however, alter the ordinary meaning of the group definition and there was no disconformity between the definition in the originating application and the statement of claim.
6. The allegations in the statement of claim concerning causation of loss and damage to group members involved a claim of market based causation. Reduced to essentials, the claim was that: there was a market for BHP Ltd shares on the ASX; the applicant and "ASX Group Members" acquired an interest in BHP Ltd shares in that market; and the market price was distorted by BHP Ltd's alleged wrongful conduct. Parallel allegations were made in respect of "LSE Group Members" and "JSE Group Members".

Commencement of VID 1077 of 2018

1. On 31 August 2018, Klemweb Nominees Pty Ltd (as trustee for the Klemweb Superannuation Fund) (Klemweb) also filed a representative proceeding against BHP Ltd (then called BHP Billiton Limited), which was given the proceeding number VID 1077 of 2018. Klemweb was represented by Maurice Blackburn Lawyers and the originating process was prepared by Brooke Dellavedova of that firm. The statement of claim was prepared by counsel and was certified by Ms Dellavedova.
2. In accordance with s 33H(1)(a) of the FCA Act, the originating application relevantly described the group members to whom the proceeding related as follows: The Group Members to whom this proceeding relates are all persons who or which:
3. during the Relevant Period entered into a contract (whether themselves or by an agent or trustee) to acquire an interest in: (a) BHP ASX Shares; (b) BHP LSE Shares; and/or (c) BHP JSE Shares,
4. suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in the Statement of Claim; and …
5. The originating application also contained the following notation: NOTE: Capitalised terms have the same meaning as in the Statement of Claim unless otherwise defined herein.
6. None of the capitalised terms "Relevant Period", "BHP ASX Shares", BHP LSE Shares" or "BHP JSE Shares" was defined in the originating application. The definitions were located in the statement of claim.
7. The Klemweb statement of claim did not merely define the foregoing capitalised terms. The statement of claim contained a stand-alone description of group members which was relevantly as follows: This proceeding is commenced as a representative proceeding pursuant to Part IVA of the Federal Court of Australia Act 1976 (Cth) by the Applicant on its own behalf and on behalf of all persons who or which: (a) during the period between 27 August 2014 and 9 November 2015 inclusive (Relevant Period) entered into a contract (whether themselves or by an agent or trustee) to acquire an interest in ordinary shares in: (i) the Respondent (BHP Ltd) on the Australian Stock Exchange (ASX) (the BHP ASX Shares); (ii) BHP Billiton plc (BHP plc) on the London Stock Exchange (LSE) (the BHP LSE Shares); and/or (iii) BHP plc on the Johannesburg Stock Exchange (JSE) (the BHP JSE Shares); (b) suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in this statement of claim; and …
8. The foregoing group definition is similar in form to the definitions in the Impiombato originating application and statement of claim. Significantly, the definition refers to persons who, during the relevant period, entered into a contract to acquire an interest in ordinary shares "on" the identified exchanges. The reference to acquiring an interest by contract does not affect the meaning of the definition. The acquisition of shares on an exchange occurs through a trade which requires an offer and acceptance. The factual findings made by the primary judge (at [13(e)]) record that a share trade on the ASX is effected by a "market contract" between the trading participant (being a broker authorised on the ASX's market) representing the buyer and the trading participant representing the seller. As such, there is no ambiguity in the group definition in the Klemweb statement of claim. The phrases that commence with the word "on" qualify the composite expression "entered into a contract to acquire an interest in" the relevant shares.
9. Like the Impiombato statement of claim, the allegations in the Klemweb statement of claim concerning causation of loss and damage to group members involved a claim of market based causation. Reduced to essentials, the claim was that: there was a market for BHP Ltd shares on the ASX; the market price was distorted by BHP Ltd's alleged wrongful conduct; and the applicant and group members who acquired an interest in "BHP ASX Shares" suffered loss and damage as a result. Parallel allegations were made in respect of "BHP LSE Shares" and "BHP JSE Shares".
10. Although the description of group members in the Klemweb proceeding has a clear meaning, it was infelicitous in numerous respects. It effectively included two descriptions, one in the originating application and one in the statement of claim. The former was an abbreviated form purporting to use defined terms from the latter. The manner in which terms were defined in the statement of claim, and then applied in the originating application and elsewhere in the statement of claim, created some grammatical difficulties. It is unfortunate that this infelicitous description of group members came to be used in the consolidated proceeding. However, as explained below, the infelicity in language did not create any ambiguity in the group definition.

Consolidation

1. On 19 July 2019, an order was made for the consolidation of the Impiombato and Klemweb proceedings pursuant to r 30.11 of the FC Rules, with the consolidated proceeding maintaining the number VID 649 of 2018. Each of Mr Impiombato and Klemweb became applicants in the consolidated proceeding. The applicants were given leave to file a consolidated originating application and a consolidated statement of claim, and were also given leave to amend the group definition in proceeding VID 649 of 2018 pursuant to s 33K(1).
2. A consolidated originating application and consolidated statement of claim were filed on 16 August 2019. The consolidated originating application was in the form considered by the primary judge. The document was prepared by Benjamin Phi of Phi Finney McDonald and Andrew Watson of Maurice Blackburn. The consolidated statement of claim was amended on 7 September 2020. The amended statement of claim was in the form considered by the primary judge. That document was prepared by counsel and certified by Mr Phi and Mr Watson. The amendments were relatively minor and are not relevant to the issue to be determined.
3. The description of group members in the consolidated originating application was materially in the same (infelicitous) form as in the Klemweb originating application. It has been set out earlier in these reasons, but it is convenient to repeat the relevant parts of the description: The Group Members to whom this proceeding relates are all persons who or which:
4. during the Relevant Period entered into a contract (whether themselves or by an agent or trustee) to acquire an interest in: (a) BHP ASX Shares; and/or (b) BHP LSE Shares; and/or (c) BHP JSE Shares;
5. …
6. are alleged to have suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in the consolidated statement of claim.
7. The description of group members in the consolidated statement of claim (as amended) was largely in the same (infelicitous) form as in the Klemweb statement of claim. The principal change was to add the description of each exchange taken from the Impiombato statement of claim. Again, it is convenient to repeat the relevant parts of the description: The Joint Applicants and the persons they represent (the Group Members) are all persons who or which: (a) during the period from 8 August 2012 to the close of trade on 9 November 2015 inclusive (Relevant Period) entered into a contract (whether themselves or by an agent or trustee) to acquire an interest in fully paid up ordinary shares in: (i) the Respondent, formerly BHP Billiton Limited (BHP Ltd), on the Australian Securities Exchange (ASX), a financial market operated by ASX Limited (the BHP ASX Shares); (ii) BHP Group Plc, formerly BHP Billiton Plc (BHP Plc), a company registered in England and Wales, on the London Stock Exchange (LSE), a financial market operated by the London Stock Exchange Group Plc (the BHP LSE Shares); and/or (iii) BHP Plc on the Johannesburg Stock Exchange (JSE), a financial market operated by the Johannesburg Stock Exchange Limited (the BHP JSE Shares); (b) … (c) are alleged to have suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in this statement of claim.
8. There is no ambiguity in the above description. Focussing on para (a)(i), group members are persons who, during the relevant period, entered into a contract to acquire an interest in fully paid up ordinary shares in BHP Ltd on the ASX and who are alleged to have suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in the statement of claim.
9. The applicants' principal argument is that the description in the originating application conveys a different meaning and should be given primacy. For the reasons given earlier, the applicants' argument based on the primacy of the originating application is unsound. Indeed, the usual starting point would be to assume harmony between the originating application and statement of claim, not disharmony, and to interpret the documents in a manner that promotes harmony. The difficulty that arises with the formulation of the group definition in the originating application comes from the use of the defined terms "BHP ASX Shares", "BHP LSE Shares" and "BHP JSE Shares". As already noted, however, the difficulty is one of infelicity of language, not ambiguity. It is clear that, in the context of the group definitions, those defined terms are intended to refer to fully paid ordinary shares in BHP Ltd and BHP Plc that are acquired on the relevant exchanges (ASX, LSE and JSE). That interpretation is both faithful to the definition of those terms in the statement of claim and produces harmony between the group definitions in the originating application and the statement of claim.
10. None of the allegations in the remainder of the statement of claim conflict with that interpretation of both the group definition and the defined terms "BHP ASX Shares", "BHP LSE Shares" and "BHP JSE Shares". Further, as found by the primary judge, the allegations concerning causation of loss provide strong support for that interpretation.
11. The statement of claim has a singular focus on the trading of ordinary shares in BHP Ltd on the ASX and the trading of ordinary shares in BHP plc on the LSE and JSE, and the markets for the trading of those shares on those exchanges. The defined terms "BHP ASX Shares", "BHP LSE Shares" and "BHP JSE Shares" are used consistently to refer to ordinary shares in BHP Ltd and BHP Plc traded or acquired on those markets.
12. The applicants' contextual arguments do no more than highlight possible superfluous language in the statement of claim. For example, the applicants refer to para 5(c) which alleges that BHP Ltd: at all material times had on issue BHP ASX Shares that were: (i) trading on the ASX under the designation "BHP"; (ii) ED securities for the purposes of s 111AE of the Corporations Act; (iii) quoted ED securities within the meaning of s 111AM of the Corporations Act; (iv) a financial product within the meaning of s 763A(1)(a) and s 764(1)(a) of the Corporations Act and s 12BAA(1)(a) and s (7)(a) of the Australian Securities and Investments Commission Act 2001 (Cth) (ASIC Act); (v) able to be acquired and sold by investors and potential investors in BHP ASX Shares on the ASX (BHP ASX Share Market).
13. It might be said that the allegation in subpara (v) that BHP ASX Shares (defined to mean fully paid ordinary shares in BHP Ltd that are traded on the ASX) were able to be acquired and sold by investors and potential investors on the ASX is otiose. On the other hand, the allegation provides a convenient means to define the expression "BHP ASX Share Market" which is used elsewhere in the statement of claim. Even if there be a degree of superfluity, there is no ambiguity.
14. Section K of the statement of claim contains allegations concerning BHP's disclosure of the Fundão Dam collapse and its consequences and the resulting share price impacts. At para 67, the applicants allege that, following the disclosure, the price of BHP ASX Shares, BHP LSE Shares and BHP JSE Shares declined significantly. The particulars refer to the closing prices for BHP Ltd shares quoted on the ASX and the closing prices for BHP Plc shares quoted on the LSE and JSE respectively. The allegation is entirely consistent with the understanding that the defined terms "BHP ASX Shares", "BHP LSE Shares" and "BHP JSE Shares" refer to ordinary shares in BHP Ltd and BHP Plc traded or acquired on those markets.
15. Section L of the statement of claim contains allegations concerning causation of loss. At paras 68 and 69, the applicants allege that:
16. During the Relevant Period, the BHP ASX Share Market was a market: (a) regulated by, inter alia, ss 674(2) and 1041H of the Corporations Act, Rule 3.1 of the Listing Rules and s 12DA of the ASIC Act; (b) in which the price at which BHP ASX Shares traded on the ASX was, and or was reasonably expected to have been, influenced by the material information concerning BHP that was published on the ASX or that otherwise became publicly available; (c) in which material information, namely the August 2012 Information, September 2012 Information, Pre-August 2014 Information, Post-August 2014 Information, General Consequential Risks and BHP Consequential Risks, had not been disclosed, which a reasonable person would expect, had it been disclosed, would have had a material adverse effect on the price or value of the BHP ASX Shares; and (d) in which misleading or deceptive conduct, namely the Representations, had occurred, which a reasonable person would expect to have a material effect on the price or value of BHP ASX Shares.
17. During the Relevant Period: (a) the Continuous Disclosure Contraventions; and (b) the Misrepresentations Contraventions, (collectively, the Contraventions) caused the price at which BHP ASX Shares traded on the ASX to be higher than their true value and/or the market price that would have prevailed but for the Contraventions (or any of them).
18. Again, those allegations are entirely consistent with the understanding that the defined term "BHP ASX Shares" refers to ordinary shares in BHP Ltd traded or acquired on the ASX. It can be accepted, as identified by the applicants, that the phrase "on the ASX" in paras 68(b) and 69 is unnecessary. The inclusion of the phrase does not, however, suggest any ambiguity in the meaning of the phrase "BHP ASX Shares" when regard is had to the whole of the pleading.
19. Similar allegations are made in respect of the "BHP LSE Share Market" and the "BHP JSE Share Market".
20. Section M of the statement of claim contains allegations that the applicants and group members suffered loss and damage. Para 81 alleges that each of the "Joint Applicants" suffered loss and/or damage in relation to their interests in BHP ASX Shares by and resulting from the alleged contraventions of the Corporations Act and the ASIC Act by BHP Ltd. The particulars of that allegation state that: The loss suffered by each of the Joint Applicants will be calculated by reference to: i. the difference between the price at which it acquired its interests in BHP ASX Shares during the Relevant Period and the true value of those interests; or ii. alternatively, the difference between the price at which it acquired its interests in BHP ASX Shares during the Relevant Period and the market price that would have prevailed had the Contraventions not occurred; or iii. alternatively, on the days when the traded price of BHP ASX Shares fell as a result of the disclosure of information the subject of the Contraventions, the quantum of that fall; or iv. alternatively, the difference between the price at which the Joint Applicants each acquired the BHP ASX Shares and whatever is "left in hand".
21. Read in the context of the remainder of the statement of claim, the allegation of loss is made by reference to the difference between the prevailing market price for BHP Ltd shares traded on the ASX at the time that each applicant acquired its shares (on that market) and the true value of the shares (or the market price of the shares that would have prevailed had the alleged contraventions not occurred). The allegation is entirely consistent with the understanding that the defined term "BHP ASX Shares" refers to ordinary shares in BHP Ltd traded or acquired on the ASX.
22. Para 82 alleges that group members who acquired an interest in BHP ASX Shares, BHP LSE Shares and/or BHP JSE Shares during the relevant period have suffered loss and/or damage in relation to their interests in those shares by and resulting from the alleged contraventions. The particulars of that allegation state that those losses will also be calculated in accordance with the particulars to para 81.
23. Significantly, the statement of claim makes no reference to shares in BHP Ltd or BHP Plc being acquired on any exchange, or in any manner, other than on the ASX, LSE or JSE. As a consequence, the statement of claim includes no allegations concerning the causation of loss in respect of an acquisition of shares in BHP Ltd or BHP Plc being acquired on any exchange, or in any manner, other than on the ASX, LSE or JSE.
24. In conclusion, the applicants' argument on the appeal finds no support in the text of the originating application and the statement of claim, including having regard to the procedural history of those documents.

The applicants' purposive arguments

1. In the absence of any true ambiguity in the group definition, the applicants' purposive arguments carry little weight.
2. The applicants' submission that there was no reason to exclude from the group definition persons who acquired shares in BHP Ltd or BHP Plc through trading platforms or exchanges other than the ASX, LSE and JSE cannot be accepted for two reasons.
3. First, the submission assumes that those responsible for preparing the proceeding were aware, at the commencement of the Impiombato and Klemweb proceedings, and then at the commencement of the consolidated proceeding, of the existence of other trading platforms or exchanges on which shares in BHP Ltd and BHP Plc were traded. None of those responsible for preparing the originating application and statement of claim gave evidence to that effect. Neither Mr Phi nor Ms Dellavedova gave evidence. Mr Watson did not address that matter, deposing that at all times "the Applicants' intention was, and remains, to bring a proceeding on behalf of all persons who acquired an interest in shares in [BHP Ltd] or BHP Plc during the Relevant Period". The statement provides no evidence as to the awareness of Chi-X or any other facility on which shares in BHP Ltd or BHP Plc were traded. It is revealing that, in his affidavit dated 15 October 2023, Mr Watson deposes that: "In preparation for the hearing on 18 October 2023, I instructed Samuel Habteslassie, an employee solicitor of [Maurice Blackburn], to undertake research relevant to the manner in which shares in ASX-listed entities … may be acquired through the Chi-X platform". The implication of that statement is that no such research had previously been undertaken by Maurice Blackburn in connection with the proceeding.
4. Second, and as found by the primary judge (at [26]), the allegations concerning causation of loss and damage in the proceeding are solely focussed on the effects of the alleged contraventions on the price of shares traded on the ASX, LSE and JSE. If a claim were to be made in respect of shares acquired through trading platforms or exchanges other than the ASX, LSE and JSE, consideration would have had to be given to causation issues associated with such claims (ie, the manner in which the alleged contraventions may have distorted the price at which such acquisitions were transacted).
5. The applicants' further argument that the objects of Pt IVA required the primary judge to adopt whatever reasonably open definition would cover as many potential group members as possible should also be rejected. Leaving aside the absence of ambiguity in the group definition (from which the argument proceeds), the objects of Pt IVA cannot be characterised in that manner. As observed by Gordon, Edelman and Steward JJ in Impiombato HC at [74], the purposes of Pt IVA include "the creation of an efficient and comprehensive mechanism for the determination of similar claims". However, the scope of the claims that are made on behalf of group members in a representative proceeding is a matter for the applicant. There is nothing in Pt IVA that encourages an applicant to bring all conceivable claims against a respondent regardless of the merits or problems of proof associated with all claims. Different applicants may assess the merits of claims differently and there is nothing in Pt IVA that prevents or discourages different applicants from bringing separate proceedings which relate to different claims and concern different group members, even if the proceedings are based on a similar substratum of facts. The Court has ample procedural powers to ensure that such proceedings are conducted efficiently and with fairness to a respondent facing multiple proceedings.

The conduct of the proceeding

1. Before the primary judge, the applicants argued that BHP Ltd had conducted the proceeding on the basis that the group definition included persons who acquired shares on other platforms. The primary judge did not accept that argument, noting that some of the materials filed by BHP Ltd mirrored the group definition in the statement of claim.
2. As discussed above, while an objective approach to the interpretation of a group definition should generally be taken, in some circumstances the conduct of the parties in the course of a representative proceeding may bear upon the interpretation. However, a compelling reason would need to be shown to depart from an objective approach. That is because of the importance of certainty in the description of group members.
3. On the appeal, the applicants were unable to substantiate their argument that BHP Ltd had conducted the proceeding on the basis that the group definition included persons who acquired shares on other platforms. It is not sufficient for the applicants to contend that BHP Ltd failed to establish the opposite: that it had conducted the proceeding on the basis that group members were persons who had acquired shares on the ASX, LSE or JSE. In the absence of compelling circumstances showing that the parties had departed from the pleaded case (and also showing that no unfairness would be caused to persons who may be brought within the group definition), the pleaded case should be taken to be determinative of the group definition.

Are acquisitions of shares on Chi-X also acquisitions on the ASX?

1. The applicants' final argument, that a trade executed on Chi-X Australia that is cleared and settled by the ASX Limited (or its subsidiaries) is also an acquisition of shares "on the ASX" for the purpose of the description of the group members, should also be rejected. The fact that trades on Chi-X are cleared and settled through processes and systems conducted by subsidiaries of ASX Limited does not support a conclusion that the trades are made or conducted "on the ASX" as defined in the statement of claim. The primary judge was correct to reject that argument (at [29]).
2. As set out earlier, para 3 of the statement of claim defines group members as persons who or which, during the relevant period, entered into a contract to acquire an interest in fully paid up ordinary shares in BHP Ltd "on the Australian Securities Exchange (ASX), a financial market operated by ASX Limited". Thus, the focus of the definition is entering into a contract to acquire shares on the exchange that is known as the Australian Securities Exchange. As explained above, the group definition is closely tied to the allegations of causation of loss. The pleaded case concerns the effect of the alleged contraventions on the price of BHP Ltd shares traded on the ASX (defined as the BHP ASX Share Market), and the loss caused to the applicants and group members by acquiring shares on that market.
3. On the basis of the evidence adduced at the hearing, the primary judge found that Chi-X operated an alternate facility through which shares in ASX listed entities (including in BHP Ltd) could be and were traded. The evidence did not descend to any detail concerning the operation of the Chi-X facility, nor the manner in which prices were set on that facility. The evidence established, however, that it was a separate exchange facility to the ASX.
4. The processes and systems by which share trades are cleared and settled are wholly irrelevant to the pleaded case. Clearance is the process by which the details of the share trade are checked and confirmed to ensure that the trade is in order. Settlement is the process by which the share trade is completed by the transfer of the shares and the payment of money. The case is concerned with the effect of the alleged contraventions on the market price of shares in BHP Ltd (and BHP Plc) as quoted on the identified exchanges. The manner in which, and the entity through which, the share trades are cleared and settled has no bearing on the allegations.

Conclusion

1. In conclusion, the applicants have failed to demonstrate error in the primary judge's conclusion that the group definition only included persons who, during the relevant period, entered into contracts to acquire ordinary shares in BHP Ltd or BHP Plc through trading on the ASX, the LSE or the JSE. The primary judge's conclusion accords with the ordinary meaning of the words used in the originating application and statement of claim, read in the context of the entirety of the claims made.
2. The applicant's appeal against the orders of the Court made on 3 November 2023 should be dismissed with costs.

C. Appeal from Impiombato No 5 - application to amend the group definition and to include additional claims

Amendments to the group definition and making new claims

1. On 5 December 2023, the applicants filed an application to amend the originating application and statement of claim in order to amend the group definition (and thereby include new group members) and to include claims in respect of the acquisition of ordinary shares in BHP Ltd and BHP Plc on trading platforms or exchanges other than the ASX, LSE and JSE, and also through off-market trades (and thereby include new claims brought on behalf of existing and new group members).
2. The amended group definition in the originating application is as follows (with the amendments marked): The Group Members to whom this proceeding relates are all persons who or which:
3. during the Relevant Period entered into a contract (whether themselves or by an agent or trustee) to acquire an interest in fully paid up ordinary shares in: (a) BHP ASX Shares the Respondent, formerly BHP Billiton Limited (BHP Ltd); and/or (b) BHP LSE Shares BHP Group Plc, formerly BHP Billiton Plc (BHP Plc), a company registered in England and Wales; and/or (c) BHP JSE Shares;
4. …
5. are alleged to have suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in the further amended consolidated statement of claim.
6. The amended group definition in para 3 of the statement of claim is as follows (with the amendments marked): The Joint Applicants and the persons they represent (the Group Members) are all persons who or which: (a) during the period from 8 August 2012 to the close of trade on 9 November 2015 inclusive (Relevant Period) entered into a contract (whether themselves or by an agent or trustee) to acquire an interest in fully paid up ordinary shares in: (i) the Respondent, formerly BHP Billiton Limited (BHP Ltd), on the Australian Securities Exchange (ASX), a financial market operated by the Australian Exchange ASX Limited (the BHP ASX Shares); and/or (ii) BHP Group Plc, formerly BHP Billiton Plc (BHP Plc), a company registered in England and Wales, on the London Stock Exchange (LSE), a financial market operated by the London Stock Exchange Group Plc (the BHP LSE Shares); and/or (iii) BHP Plc on the Johannesburg Stock Exchange (JSE), a financial market operated by the Johannesburg Stock Exchange Limited (the BHP JSE Shares); (b) … (c) are alleged to have suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in this statement of claim.
7. It can be seen that the amended group definition in the originating application and the statement of claim was expanded to include all persons who entered into a contract to acquire ordinary shares in BHP Ltd and/or BHP Plc during the relevant period regardless of the circumstances in which they entered into the contract. The amended group definition covers three categories of persons. The first category comprises persons who, during the relevant period, entered into one or more contracts to acquire shares in BHP Ltd and/or BHP Plc only on the ASX, LSE and JSE. Those persons are existing group members and are not affected by the amendments. The second category comprises persons who, during the relevant period, entered into contracts to acquire shares in BHP Ltd and/or BHP Plc on the ASX, LSE and JSE and also on one or more other trading platforms or exchanges. Again, those persons are existing group members. However, the amendments to the statement of claim include claims made in respect of the shares acquired by them on trading platforms and exchanges other than the ASX, LSE and JSE which were not previously made in the proceeding. The third category comprises persons who, during the relevant period, entered into one or more contracts to acquire ordinary shares in BHP Ltd and/or BHP Plc only on trading platforms and exchanges other than the ASX, LSE and JSE. Those persons are new group members and the claims made on their behalf are new claims in the proceeding.
8. The amendments to the statement of claim to include new claims in respect of the acquisition of ordinary shares in BHP Ltd and BHP Plc on trading platforms or exchanges other than the ASX, LSE and JSE can be summarised as follows.
9. First, the applicants introduced new concepts of BHP Ltd Share Markets and BHP Plc Share Markets.
10. Paragraph 5(c)(v) was amended to allege that ordinary shares in BHP Ltd (defined as BHP Ltd Shares) were able to be acquired and sold by investors and potential investors in BHP Ltd Shares on, inter alia, the ASX (defined as BHP Ltd Share Markets). The particulars to that allegation are that: All ordinary shares in BHP Ltd (ie, all BHP Ltd Shares) were quoted on the ASX and were able to be acquired and sold by investors and potential investors on the ASX and/or on other financial markets or trading platforms, such as Chi-X Australia, or by other means of trading, such as off market trades.
11. Paragraph 8(a)(iii) was amended to allege that ordinary shares in BHP Plc (defined as BHP Plc Shares) were able to be acquired and sold by investors and potential investors in BHP Plc Shares on, inter alia, the LSE and the JSE (defined as BHP Plc Share Markets). The particulars to that allegation are that: All ordinary shares in BHP Plc (ie, BHP Plc Shares) were listed on the LSE and on the JSE and were able to be acquired and sold by investors and potential investors on the LSE, JSE and/or other financial markets or trading platforms, such as BATS Chi-X Europe, or by other means of trading, such as off market trades.
12. Second, the applicants alleged that, following the announcement made by BHP Ltd on 6 and 9 November 2015 concerning the collapse of the Fundão Dam, the price of BHP Ltd Shares and BHP Plc Shares declined significantly. The particulars to that allegation refer to the prices quoted on each of the ASX, LSE and JSE and state that "further particulars will be provided after expert evidence and the determination of common questions". Thus, as amended, the statement of claim does not presently contain particulars about the alleged decline in the price of BHP Ltd Shares and BHP Plc Shares on any trading platform or exchange other than the ASX, LSE and JSE.
13. Third, the applicants have broadened their allegations concerning the causation of loss to include trading platforms and exchanges other than the ASX, LSE and JSE.
14. Relevantly, para 68 has been amended to allege (amongst other things) that BHP Ltd Share Markets were markets:
15. in which the disclosure by BHP Ltd of information concerning BHP was regulated by, inter alia, ss 674(2) and 1041H of the Corporations Act, Rule 3.1 of the ASX Listing Rules and s 12DA of the ASIC Act; and
16. in which the price at which BHP Ltd Shares traded was, and was reasonably expected to have been, influenced by the material information concerning BHP that was published on or to the ASX or that otherwise became publicly available.
17. Paragraph 69 has been amended to allege that the alleged contraventions of the Corporations Act and ASIC Act caused the price at which BHP Ltd Shares traded to be higher than their true value and/or the market price that would have prevailed but for the contraventions.
18. A new para 69A has been added to allege that the applicants and those group members who acquired an interest in BHP Ltd Shares during the relevant period did so at a price that was higher than their true value and/or the market price that would have prevailed but for the alleged contraventions.
19. Equivalent amendments have been made with respect to BHP Plc Shares.
20. In so far as the allegations concern the acquisition of BHP Ltd Shares and BHP Plc Shares on trading platforms or share markets other than the ASX, LSE and JSE, the pleading states that "further particulars will be provided following expert evidence and the determination of common questions". In other words, as amended, the statement of claim does not presently contain any particulars concerning the causation of loss with respect to shares acquired by group members on any trading platform or exchange other than the ASX, LSE and JSE.

The potential application of statutory limitation periods

1. As noted earlier, BHP Ltd did not oppose the grant of leave to the applicants to amend the originating application and the statement of claim. BHP Ltd only opposed the application for an order that the amendments take effect from the commencement of the proceeding on 31 May 2018. The purpose and effect of that order, which was made by the primary judge, is to avoid the potential application of statutory limitation periods to the claims made on behalf of new group members and the new claims made on behalf of existing group members.
2. The statutory limitation periods applicable to the causes of action pleaded by the applicants in the proceeding are as follows:
3. In respect of the claim for compensation for loss suffered as a result of the alleged contravention of the continuous disclosure obligation in s 674(2) of the Corporations Act made pursuant to ss 1317HA, s 1317K relevantly stipulated that proceedings must be started no later than 6 years after the contravention (which, on the allegations made, was no later than the day 6 years after the end of the relevant period on 9 November 2015).
4. In respect of the claim for compensation for loss suffered as a result of the alleged contravention of the continuous disclosure obligation in s 674(2) of the Corporations Act made pursuant to ss 1325 of the Corporations Act, the applicable limitation period depends upon the subsection of s 1325 relied on by the applicants (which is not identified in the originating application). If the claim for compensation is made under s 1325(1), the applicable limitation period is that which applies to the primary claim for relief to which the claim under s 1325(1) attaches (see Sent v Jet Corporation of Australia Pty Ltd (1986) 160 CLR 540 in respect of the analogous remedy in s 87 of the Trade Practices Act 1974 (Cth), now named the Competition and Consumer Act 2001 (Cth)). In this case, the proceeding must be taken to have been instituted under s 1317HA, to which a 6 year limitation period applies as noted in the preceding paragraph. If the claim for compensation is made under s 1325(2), the applicable limitation period is governed by s 1325(4) which stipulates that an application under s 1325(2) may be made within 6 years after the day on which the cause of action arose (which, on the allegations made, was no later than the day 6 years after the end of the relevant period on 9 November 2015).
5. In respect of the claim for compensation for loss suffered as a result of the alleged contravention of the misleading and deceptive conduct prohibition in s 1041H(1) of the Corporations Act made pursuant to s 1041I(1) of the Corporations Act, s 1041I(2) stipulated that an action must be begun no later than 6 years after the day on which the cause of action arose (which, on the allegations made, was no later than the day 6 years after the end of the relevant period on 9 November 2015).
6. In respect of the claim for compensation for loss suffered as a result of the alleged contravention of the misleading and deceptive conduct prohibition in s 12DA(1) of the ASIC Act made pursuant to s 12GF(1) and 12GM of the ASIC Act, s 12GF(2) relevantly stipulated that an action must be commenced within 6 years after the day on which the cause of action accrued (which, on the allegations made, was no later than the day 6 years after the end of the relevant period on 9 November 2015).
7. The application of limitation periods to claims made in a representative proceeding is affected by s 33ZE(1) which provides as follows: Upon the commencement of a representative proceeding, the running of any limitation period that applies to the claim of a group member to which the proceeding relates is suspended.
8. It can be seen that s 33ZE only applies to the claim of a group member, and only applies to claims "to which the proceeding relates". It follows that s 33ZE has no application to the new claims, introduced by the amendments, made on behalf of new group members (persons who only acquired shares in BHP Ltd or BHP Plc on trading platforms or exchanges other than the ASX, LSE and JSE). A more difficult question, which arose before the primary judge, is whether s 33ZE applies to the new claims, introduced by the amendments, made on behalf of existing group members. We will turn to the position of existing group members first.

New claims made on behalf of existing group members

1. The parties disagree with respect to the application of s 33ZE to the amended claims, made on behalf of existing group members, relating to the acquisition of shares on trading platforms or exchanges other than the ASX, LSE and JSE.
2. The applicants submitted before the primary judge, and on the appeal, that the limitation periods applicable to those amended claims had been suspended from the commencement of the proceeding by s 33ZE. An incongruity of the applicants' submission is that, if it is correct, the applicants do not require an order from the Court that the amendments, in so far as they relate to the claims of existing group members, take effect from the commencement of the proceeding. On the applicants' argument, the limitation periods applicable to those claims have been suspended since the commencement of the proceeding.
3. BHP Ltd submitted that s 33ZE only applies to the claim of a group member to which the proceeding relates and that, prior to the amendments, the proceeding did not relate to claims in respect of the acquisition of shares on trading platforms or exchanges other than the ASX, LSE and JSE.
4. Without deciding the issue, the primary judge said that there were reasons to doubt the contention advanced by BHP Ltd. His Honour reasoned (at [254]-[255]) that: … In order to be a group member in the proceeding a person must have a "claim" under s 33C of the FCA Act: Impiombato (HC) at [55] (Gordon, Edelman and Steward JJ). A "claim" under s 33C is not limited to the pleaded causes of action, nor does having a "claim" mean that the person has a right or entitlement to relief; rather, it means "that there exists facts, circumstances and legal rights anterior to and independent of the class action, which may ground a right or entitlement to relief when that person's claim is ultimately heard and determined by the Court": Dyczynski at [168] (Murphy and Colvin JJ). The new claims for relief proposed to be introduced through the Loss Amendments arise from the same facts, circumstances and legal rights as the causes of action pleaded and they form part of the group members' "claims" (in the s 33C sense) to which the proceeding already relates. Pursuant to s 33ZE, upon commencement of the proceeding, any limitation periods applicable to group members' claims were suspended …
5. Respectfully, it is not entirely correct to say that the new claims for relief arise from the same facts, circumstances and legal rights as the causes of action pleaded. As BHP Ltd submitted, the new allegations, concerning the acquisition of shares on trading platforms and share exchanges other than the ASX, LSE and JSE, involve different factual circumstances to share acquisitions on the ASX, LSE and JSE, and raise different issues of causation of loss. And as observed earlier, the applicants are unable at this point in time to provide particulars of the allegations of causation of loss in respect of the acquisition of shares on different trading platforms and share exchanges. The applicants merely state that further particulars will be provided following expert evidence and the determination of common questions. To a considerable extent, the applicants' case with respect to the causation of loss and damage from the acquisition of shares on trading platforms and share exchanges other than the ASX, LSE and JSE is unknown at this time. It is correct to say, however, that the new claims are based on or arise out of substantially the same facts as those already pleaded, as the new claims are based on the same wrongful conduct that is alleged against BHP Ltd and, like the existing claims, concern the acquisition of ordinary shares in BHP Ltd and BHP Plc.
6. To date, the meaning of the phrase "the claim of a group member to which the proceeding relates" has received little judicial consideration. The view taken by the primary judge is that the phrase references s 33C, such that s 33ZE applies to all claims of group members that satisfy the conditions in paras (b) and (c) of s 33C. An alternative view, as advanced by BHP Ltd, is that the phrase refers to those claims that are advanced through the proceeding, which will be specified (as required by s 33H) by the originating application and the pleading or other document filed in support of the originating application.
7. On this appeal, we have concluded that it is unnecessary to express any final view on the proper construction of s 33ZE and its application in the circumstances of this case. For the reasons explained below, we consider that it is appropriate to make an order that the amendments to the claims made on behalf of existing group members should relate back to the commencement of the proceeding. We consider that that is the appropriate order to be made even if BHP Ltd is correct and s 33ZE has no application in the circumstances of this case (because the new claims for relief made on behalf of existing group members in respect of the acquisition of shares in BHP Ltd and BHP Plc on trading platforms and share exchanges other than the ASX, JSE and LSE are not claims to which the proceeding related prior to the amendments). In other words, proceeding on the basis that is favourable to BHP Ltd (that the new claims made on behalf of existing group members are time-barred), we consider that the order sought by the applicants should be made.

Claims made on behalf of new group members

1. As noted above, s 33ZE has no application to the new claims made on behalf of new group members (persons who only acquired shares in BHP Ltd or BHP Plc on trading platforms or exchanges other than the ASX, LSE and JSE). Before the primary judge, the applicants conceded that, unless the amendments took effect from the commencement of the proceeding on 31 May 2018, or the limitation periods applicable to the claims made in the proceeding were extended, BHP Ltd would be able to raise limitations defences in respect of the claims made on behalf of new group members. The primary judge proceeded on that basis (at [256]) and there is no challenge to that aspect of his Honour's decision.
2. The primary judge also considered whether new group members are entitled to make an application under s 1322(4)(d) of the Corporations Act to extend the limitation periods applicable to the claims made in the proceeding under the Corporations Act. Section 1322(4)(d) stipulates that the Court may make "an order extending the period for … taking any proceeding under this Act … (including an order extending a period where the period concerned ended before the application for the order was made)". Section 1322(6) stipulates that the Court must not make such an order unless it is satisfied that no substantial injustice has been or is likely to be caused to any person.
3. As observed by the primary judge (at [192]), on its face s 1322(4)(d) would appear to empower the Court to extend the limitation periods referred to in ss 1041I(2) and 1317K of the Corporations Act. The primary judge stated that different judicial views have been expressed as to when s 1322(4) may be invoked. Respectfully, the current weight of authority is to the effect that s 1322(4)(d) does not apply in respect of provisions, such as s 1317K, which impose a time limitation having a "jurisdictional character" (in the sense of denying the right of action and not merely the right to certain forms of relief): see Newtronics Pty Ltd v Gjergja [2008] VSCA 117; 219 FLR 1; Austructures Pty Ltd v Makin [2014] VSC 544; 290 FLR 153 and Binqld Finances Pty Ltd (in liq) v Binetter [2024] FCA 361. The same reasoning is applicable to the time limitation in s 1041I(2). A different view was reached in respect of s 1325(4) in Karl Suleman Enterprizes Pty Ltd (in liquidation) v Pham [2013] NSWSC 110; 273 FLR 127 at [113]-[114].
4. The primary judge concluded that, for the purposes of the amendment application, it was unnecessary to decide whether an application to extend the date by which the new claims are brought could be made under s 1322(4)(d). His Honour considered it enough to note the possibility that the date could be extended by the Court under that power (at [192]). Having regard to the current state of the authorities, we respectfully consider it appropriate to proceed on the basis that the power under s 1322(4)(d) is unlikely to be available in respect of the time limitations in ss 1317K and 1041I(2). However, as no such application is before us, it is unnecessary to consider the question further or express any firm view on the matter.

Evidence adduced on the application to amend

1. In support of the application to amend, the applicants read three affidavits of Cameron Myers, a principal lawyer with Phi Finney McDonald, sworn 5 December 2023, 26 February 2024 and 29 February 2024, and an affidavit of Ms Irina Lubomirska, Special Counsel with Maurice Blackburn, affirmed 29 February 2024.
2. The primary judge recorded that the annexures to Mr Myers' affidavits included the following affidavits that had been previously filed in the proceeding:
3. an affidavit of Mr Timothy Finney, a partner of Phi Finney McDonald, affirmed 13 July 2018;
4. an affidavit of Mr Benjamin Phi, a partner of Phi Finney McDonald, affirmed 16 October 2018;
5. an unsworn affidavit of Mr Jason Betts, a partner of Herbert Smith Freehills, the solicitors for BHP Ltd, dated 26 June 2020 (which his Honour noted was likely filed unsworn pursuant to Court protocols adopted during the COVID-19);
6. an affidavit of Ms Christine Tran, a partner of Herbert Smith Freehills, affirmed 11 December 2020; and
7. two affidavits of Mr Andrew Watson, then a partner of Maurice Blackburn Lawyers, sworn 15 October 2023 and 27 October 2023.
8. It is important to recognise that the affidavits annexed to Mr Myers' affidavits were not read into evidence. As such, none of Mr Finney, Mr Phi, Mr Betts, Ms Tran or Mr Watson can be regarded as having given evidence at the interlocutory hearing. Only Mr Myers and Ms Lubomirska gave evidence. The effect of annexing the affidavits to Mr Myers' affidavit was equivalent to tendering the annexed affidavits as documentary evidence. As explained by Perram J in Hua Wang Bank Berhad v Federal Commissioner of Taxation (No 15) (2013) 217 FCR 26 at [14], when an affidavit is tendered in evidence, as opposed to being read (as a form of testimonial evidence), the affidavit constitutes hearsay evidence but may be admissible if an exception to the hearsay rule is engaged. A further consequence, as noted by Perram J, is that the opposing party does not have a right to cross-examine the maker of the affidavit (s 27 of the Evidence Act 1995 (Cth) (Evidence Act) does not apply because the maker of the affidavit is not giving evidence as a witness). Nevertheless, pursuant to s 167 of the Evidence Act, the opposing party may request the party tendering the affidavit to call the maker of the affidavit as a witness so that the maker can be cross-examined about the contents of the affidavit. No such request was made in this case.
9. The annexed affidavits were admissible on the amendment application before the primary judge under s 75 of the Evidence Act as the application was interlocutory. Further, it is apparent that the applicants sought to tender the affidavits of Mr Betts and Ms Tran, who were solicitors representing BHP Ltd, as admissions against interest.
10. On the appeal, BHP Ltd challenges certain factual findings made by the primary judge on the basis of the above evidence, including a finding that the applicants and their solicitors always intended that the proceeding be brought on behalf of all persons who acquired shares in BHP Ltd and BHP Plc during the relevant period, without limitation by reference to the exchange or trading platform upon which that occurred, but failed to reflect that intention in the pleading by mistake. In making that finding, the primary judge relied on the evidence given by Mr Myers and Ms Lubomirska and also the statements made by Mr Watson in his affidavits that were annexed to Mr Myers affidavits. The ground of appeal concerns the quality of that evidence in light of other evidence before the primary judge. There was no evidence that Mr Myers or Ms Lubomirska prepared the pleadings. While Mr Watson certified the consolidated pleading (following the consolidation of the Impiombato and Klemweb proceedings), Mr Watson did not give evidence but his affidavits were tendered. It will be necessary to return to these matters when considering BHP Ltd's grounds of appeal concerning the factual findings made by the primary judge.
11. For completeness, it is also noted that BHP Ltd read an affidavit of Ms Tran affirmed 2 February 2024.

The Court's power to grant leave to amend a group definition and to order the amendments to relate back to the commencement of the proceeding

1. The primary judge concluded that the Court has power to grant leave to amend a group definition, whether it appears in an originating application or a statement of claim, and for the amendments to relate back to the commencement of the proceeding, notwithstanding that the application is made after the expiry of a limitation period (at [106]). His Honour's conclusions with respect to the Court's power can be summarised as follows:
2. Section 33K(1) empowers the Court to grant leave to an applicant to amend the group definition in the originating application, and s 33K(4) empowers the Court to make any other order it thinks just. Despite its heading, the power conferred by s 33K is not confined to an amendment to include persons whose cause of action accrued after the commencement of the proceeding (at [98]). There is nothing in s 33K(1) to indicate that an amendment to a group definition will only take effect from the date of amendment, and the Court has power under ss 33K(1) and (4) to order that an amendment to a group definition in an originating application takes effect from the date of commencement of the proceeding (at [100]).
3. Section 33K does not preclude the operation of the FC Rules as a source of power to amend an originating application (at [101]). In particular, r 8.21 of the FC Rules (together with rr 1.32, 1.33, 1.34 and 1.35 to the extent necessary), made pursuant to s 59(2B) of the FCA Act, is also a source of power. In that regard, the circumstances enumerated in r 8.21(1) are not an exhaustive statement of the circumstances in which the Court may grant leave for an amendment to an originating application, and the circumstances in r 8.21(2) are not an exhaustive statement of the circumstances in which the Court may grant leave for an amendment to relate back to an earlier date, even if the application is made after the end of any relevant limitation period (at [104]).
4. By an infelicity in the drafting of s 33K(1), the section only empowers the Court to grant leave to amend a group definition where it appears in an originating application. However, the section does not give rise to a negative implication that a group definition contained in a statement of claim cannot be amended (at [99]).
5. The Court has power to amend a group definition contained in a statement of claim under s 33ZF which authorises the Court to "make any order the Court thinks appropriate or necessary to ensure justice is done in the proceeding". Depending upon the circumstances of the case, it may be appropriate or necessary to ensure justice is done in the proceeding to grant leave to amend a group definition in a statement of claim and for the amendment to relate back to the commencement of the proceeding (at [105]).
6. Although BHP Ltd contends on the appeal that the primary judge's consideration of the Court's power to permit the amendments involved error, it did not contend that the Court lacks power to permit the amendments to relate back to the commencement of the proceeding. The issues raised on the appeal primarily concern the principles governing the exercise of the Court's discretion.

Principles relevant to the grant of leave to amend and to order the amendments to relate back to the commencement of the proceeding

1. The primary judge summarised the principles that guide the exercise of the Court's discretion to permit an amendment, and to order the amendments to relate back to the commencement of the proceeding, under four headings.
2. First, his Honour referred (at [107]) to the general principles that guide the grant of leave to amend as summarised by Gilmour and Foster JJ in Caason Investments Pty Ltd v Cao (2015) 236 FCR 322 at [19]-[21]:
3. the power of the Court to grant or refuse leave to amend must be exercised in the way that best promotes the Court's overarching purpose to facilitate the just determination of disputes according to law as quickly, inexpensively and efficiently as possible;
4. the Court's power to grant leave to amend is a broad power which has the remedial objective of ensuring that any defect is cured and that the real issues in the dispute are properly agitated;
5. the object of the Court is not to punish parties for mistakes made in the conduct of their case, but to correct errors with the result that a decision can be made on the real matters in controversy; and
6. leave to amend should be granted unless the proposed amendment is futile or where the amendment would cause substantial prejudice or injustice to the opposing party in a way that cannot be compensated by an award of costs.
7. Second, his Honour referred to the principles that guide the exercise of discretion to order that an amendment take effect from the commencement of the proceeding rather than the date of the amendment, notwithstanding that a limitation period applicable to the new claim has expired since the commencement of the proceeding. His Honour observed (at [109]) that the cases distinguish between two categories of amendments:
8. those which would introduce a new cause of action after the limitation period for its commencement has expired; and
9. those which would add a new defendant after the applicable limitation period against that defendant has expired.
10. In relation to the first category, his Honour noted (at [110]) that an originating application and a statement of claim may be amended to add a new claim for relief if the claim arises out of the same or substantially the same facts as the existing claims. This principle is reflected in rr 8.21(1)(g)(i) and (2) and 16.53(2) of the FC Rules. In relation to the second category, his Honour noted (at [111]) that the usual position is that an amendment which joins a defendant takes effect from the date of amendment (such that any applicable limitation defence will remain available to the newly joined defendant).
11. Third, and under a separate heading, his Honour referred to the circumstance in which an amendment is sought to be made to correct a mistake in the name or identity of a party. His Honour noted (at [112]) that amendments to correct a mistake in the name or identity of a party are another category of cases in which the courts often allow amendments to relate back to the commencement of a proceeding notwithstanding that, since the commencement of the proceeding, the applicable limitation period has expired. His Honour continued (at [112]): The proposed Group Definition Amendments are not, of course, amendments to correct a mistake in the name or identity of a party. Group members are not parties, and an amendment to a group definition to expand the class does not mean that the new group members are becoming parties: Ethicon Sàrl (at [50]). Even so, orders granting leave to correct a lawyer's mistake in the name or identity of a party and thereby adding a party to a proceeding, and orders granting leave to correct a lawyer's mistake in a group description and thereby adding group members to a proceeding, have some similarities.
12. His Honour further observed (at [113]) that rr 8.21(c) and (d) and 8.21(2) of the FC Rules authorise the Court to grant leave to amend an originating application to correct a mistake in the name of a party or to correct the identity of a party notwithstanding that the amendments are made after the expiry of applicable limitation periods. His Honour surveyed a number of authorities which have considered and applied analogous rules of court in various Australian jurisdictions, including Bridge Shipping Pty Ltd v Grand Shipping SA (1991) 173 CLR 231 (Bridge Shipping), Brown v Jammal [1995] NSWCA 62 (Brown v Jammal) and Nikolay Malakhov Shipping Co Ltd v SEAS Sapfor Ltd (1998) 44 NSWLR 371 (Nikolay Malakhov Shipping). Each case turned on its own facts, but his Honour highlighted the following observation of McHugh J in Bridge Shipping (at 260-261, with which Brennan and Deane JJ agreed) concerning r 36.01(4) of the Supreme Court Rules 1986 (Vic) (which is analogous to r 8.21(c) of the FC Rules): Rule 36.01(4) is a remedial rule and should be given a beneficial interpretation. It is proper to give it the widest interpretation which its language will permit. It should be interpreted to cover not only cases of misnomer, clerical error and misdescription but also cases where the plaintiff, intending to sue a person he or she identifies by a particular description, was mistaken as to the name of the person who answers that description. …
13. His Honour also noted that statements to similar effect were made by Kirby P (with whom Handley and Sheller JJA agreed) in Brown v Jammal (at 7) and by Sheller JA in Nikolay Malakhov Shipping, who observed (at 395-396): The exercise by the court of a power to correct such a mistake seems to me to be procedural albeit that the existence of the mistake may have allowed the party to raise a defence for so long as the mistake remained uncorrected. I see no reason why a party should be permitted to rely upon a defence available to it only because of a mistake by the other party's solicitor of the sort which occurred in the present case, when the Court, which is hearing the proceedings, has the means to correct the mistake and the party added as a result of the correction is in no worse position than if the mistake had not been made in the first place. To refuse such an application allows technicality to prevail over merit, a result the courts should strive to avoid. As McHugh J said in Bridge Shipping Pty Ltd v Grand Shipping SA (at 260-261) of an equivalent provision, it is a remedial rule and should be given a beneficial interpretation.
14. Fourth, his Honour referred to amendments to the description of group members under s 33K of the FCA Act and the discretion to order that the amendment takes effect from the commencement of the proceeding rather than the date of the amendment. In that regard, his Honour referred to the following observations made by the Full Court in Ethicon Sàrl (at [49]-[52]): 49 The second difficulty is more significant and relates to the inaptness, or at least the limitations of, drawing analogies between aspects of ordinary inter partes litigation and Part IVA procedures. Although s 33ZG provides that nothing in Part IVA affects the Court's powers under other provisions, Part IVA provides its own bespoke and detailed regime and, in significant respects, the evident purpose of the Part is to displace generally understood procedures: see Wong v Silkfield Pty Ltd [1999] HCA 48; 199 CLR 255 at 260-261 [11] (Gleeson CJ, McHugh, Gummow, Kirby and Callinan JJ). 50 By the amendment of a group definition, a new group member affected is not becoming a party, still less is the group member an existing party seeking to bring a new cause of action arising out of similar circumstances. The legal consequence is that the claim of a new group member, which claim gives rise to at least one substantial issue of law or fact with others, has become subject to the operation of the Part, subject to opt out or declassing. When one recognises that the regime expressly contemplates and provides for the individuality of claims within a group proceeding, what is brought into focus is that an order for amendment, which has the consequence of expanding the group definition, is sui generis and that analogies drawn from other contexts are apt to mislead. 51 It is consistent with the scheme introduced by Part IVA and, in particular, the need for there to be certainty as to the persons who comprise the class at all times, that the Group Definition Amendment should have been ordered to take effect from the date of amendment, being the date of filing of the 5FASOC. To adopt that course is consistent with the expansion of the class effected by the earlier Amendment Orders which, unfortunately, were not drawn to the attention of the primary judge in the present context. Apart from anything else, this prevents the topsy turvy notion that someone retrospectively becomes a group member on commencement, when the Court has thus far proceeded on the basis that they are not group members. As a matter of principle, such an approach would avoid the vice of potentially resuscitating causes of action by persons who have never sought to agitate them. It would be odd that by becoming a group member through the augmentation of a class, substantive rights were conferred on a claimant that had been either extinguished or barred by operation of statute and could not otherwise be advanced by that claimant. 52 Before leaving this topic it is worth making a further point. Given the suspension of limitations caused by the operation of s 33ZE, the question of inclusion (or, as occurred here, unusually, exclusion) of group members has potentially important consequences on substantive rights. As does the date when any such order is to take effect. Whatever might be the nature of other amendments to a statement of claim, or to relief claimed in an application, attention must be given by parties to the legal consequences of class composition changes. Irrespective as to when other amendments might take effect, the consequences of amendments to group definition can affect the rights of third parties, being the absent group members or proposed group members. Although it would be inappropriate to lay down inflexible rules, the default position is that a s 33K order (or an equivalent order under s 33ZF) has effect from the time the definition is changed, consistent with the requirements of class certainty. It is a sound practice for applicants, in seeking such orders, to deal separately with amendments concerning class composition to assist in avoiding any confusion. Although it would be inappropriate to lay down inflexible rules, the default position is that a s 33K order (or an equivalent order under s 33ZF) has effect from the time the definition is changed, consistent with the requirements of class certainty.

Relevant findings of fact

1. The primary judge made factual findings on the following topics relevant to the exercise of his Honour's discretion with respect to the amendments.
2. The first topic was whether the applicants, or their solicitors, intended from the outset to make a claim on behalf of group members in respect of the acquisition of shares in BHP Ltd and BHP Plc regardless of the trading platform or share exchange on which the acquisition occurred, but failed to give effect to that intention by mistake (erroneous drafting of the originating application and statement of claim). His Honour found that fact to be established by reference to evidence given by Mr Watson and Ms Irina Lubomirska of Maurice Blackburn and by Mr Cameron Myers of Phi Finney McDonald (at [141]). His Honour expressed his ultimate finding as follows (at [151]): I am satisfied on the evidence that at all material times the intention of the first and second applicants, and also of MB and PFM, was to bring the proceeding on behalf of all persons who acquired an interest in BHP Shares during the Relevant Period, irrespective of the trading platform upon which that occurred. I accept Mr Myers' evidence that the framing of the group definition in the way that it is was an "inadvertent mistake in drafting". The operative mistake was the applicants' lawyers inadvertently framing the group definition in a way which was inconsistent with the applicants' intention, and indeed the solicitors' own intention. The applicants' lawyers should have ensured that the group definition accorded with their clients' understanding of the case to be brought, and they did not.
3. The finding that the formulation of the group definition (and, it follows, the formulation of the claims made in respect of the acquisition of shares on the ASX, LSE and JSE but not on other trading platforms and share exchanges) was a drafting error or mistake made by the applicants' lawyers was crucial to his Honour's decision to permit the amendments to date from the commencement of the proceeding (see for example at [154], [160], [180], [193], [212], [217]-[220], [225]-[232], [240]).
4. The second topic concerned the prejudice that would be suffered by existing group members in proving their claims if the amendments do not take effect from the commencement of the proceeding. In those circumstances, it would be necessary for existing group members to prove that they are, in fact, an existing group member by proving that they had acquired at least some shares in BHP Ltd or BHP Plc on the ASX, LSE and JSE during the relevant period. The primary judge found that it is likely to be very difficult, time consuming and expensive (and perhaps impossible) for persons to prove which share exchange their shares were acquired on (at [176]-[177]). In that regard, his Honour took into account the facts that:
5. Ascertaining the trading platform used to execute a share acquisition cannot be determined by reference to share registry data (at [162]).
6. Most retail investors execute market trades through brokers, including online brokers, and do not provide instructions as to the trading platform upon which their trade is to be executed, and most brokers do not provide retail investors with details of the trade platform used to execute a trade (at [163]).
7. For those group members who did provide instructions to their brokers as to the trading platform upon which to execute the share trade, once the share trade was executed it is likely that many such group members did not retain those instructions as there would be no good reason to keep them (at [165(b)]).
8. As a consequence of the foregoing, in order for group members to establish that they are in fact group members, it will be necessary for them to make enquiries of their brokers to identify the trading platforms on which the relevant share trades were executed (at [166]).
9. During the relevant period, 14.5 billion shares in BHP Ltd and BHP Plc were traded on the ASX, LSE and JSE during the relevant period. If brokers have retained some relevant share transaction records from that period, having regard to the number of share transactions during the period, the enquiries of brokers to establish that each of those acquisitions was, in fact, on the ASX, LSE or JSE will be factually intensive, time-consuming, expensive (in aggregate) and likely to take a substantial period of time (at [167]).
10. During the relevant period, all but one of the major Australian retail brokers had access to multiple trading platforms, and the same is likely to be true of major overseas retail brokers (at [168]).
11. Approximately 14.5 billion shares in BHP Ltd and BHP Plc were traded on the ASX, LSE and JSE during the relevant period, and approximately 3.3 billion shares in BHP Ltd and BHP Plc were traded on other platforms or exchanges during that period. The likely usage of multiple trading platforms by major Australian retail brokers, major overseas retail brokers and investment banks means that it is likely that many existing group members had shares in BHP Ltd and BHP Plc acquired for them during the relevant period on trading platforms and share exchanges other than the ASX, LSE and JSE. It is likely to be necessary for many existing group members to undertake factually intensive, time-consuming and costly enquiries to establish that they are, in fact, a group member (at [169]).
12. Pursuant to the applicable exchange rules, brokers are required to keep share transaction records for the following periods:
    1. on the ASX and on Chi-X Australia, for seven years;
    2. on Chi-X Europe and on the JSE, for five years (and in relation to client instructions on the JSE, for six months); and
    3. on the LSE, for three years (at [170]).
13. Having regard to the relevant period of share acquisitions the subject of the claims made in the proceeding, it is now many years after the expiry of the period in which brokers are required to keep share transaction records (at [171]).
14. The major Australian retail brokers are required, pursuant to their own privacy policies, to delete all personal information records as soon as that information is no longer required. It is likely that many brokers will destroy their share transaction records as soon as they are lawfully able to do so, as that is what their privacy policies require. Having regard to that, and also to the likely costs associated with retention of share transaction data over a lengthy period, it is likely that many major Australian retail brokers will not have retained their share transaction records beyond the required seven-year period under the ASX Rules (at [172]). The same conclusions are applicable to brokers operating on overseas exchanges (at [173]).
15. The third topic concerned the effect of limitation defences if the amendments were not dated from the commencement of the proceeding. The applicable limitation periods were summarised earlier. On this topic, the primary judge concluded that the position of new group members differed from existing group members. The primary judge concluded that, if the amendments were not dated from the commencement of the proceeding, new group members would be disadvantaged in comparison to existing group members because they will not be entitled to share in the benefit of any favourable settlement or judgment (at [155]). In making that finding, his Honour implicitly accepted that the new claims made on behalf of the new group members would be barred by the applicable limitation periods. However, the primary judge also concluded that this prejudice does not carry substantial weight in the exercise of the discretion (to grant leave to amend dating from the commencement of the proceeding). That is because the new group members were not, and never had been, group members in the proceeding (at [155]). His Honour also refused to make a finding that the new group members had reasonable grounds to believe that they were group members in the proceeding (at [156]), and accordingly refused to make a finding that new group members have suffered prejudice by reason of the fact that they had not taken steps to make a claim against BHP Ltd (at [158]).
16. In respect of existing group members, the relevant question was whether the new claims introduced by the amendments, being in respect of the acquisition of shares on trading platforms and share exchanges other than the ASX, LSE and JSE, would be barred by the applicable limitation periods. As noted earlier, on that issue his Honour concluded that the limitation periods applicable to the new claims made on behalf of existing group members were likely suspended by s 33ZE (at [255]). It logically followed from that conclusion, and his Honour found, that this category of prejudice did not arise for existing group members.
17. In respect of BHP Ltd, the primary judge concluded that there would be no prejudice to BHP Ltd by permitting the new claims of existing group members to date from the commencement of the proceeding (at [255]). That conclusion followed from his Honour's finding that the limitation periods applicable to the new claims made on behalf of existing group members were likely suspended by s 33ZE. Conversely, the primary judge concluded that there would be some prejudice to BHP Ltd by permitting the claims of new group members to date from the commencement of the proceeding, because the new claims would increase BHP Ltd's potential aggregate liability in the proceeding. However, his Honour found that the increase in BHP Ltd's potential liability would not be material having regard to the substantial quantum of the claims already made in the proceeding (at [182] and [187]). His Honour made that finding on the basis of the following matters:
18. His Honour accepted (at [183]) that, during the relevant period, a total of approximately 14.5 billion shares in BHP Ltd and BHP Plc were traded on the ASX, LSE and JSE and a total of approximately 3.3 billion shares in BHP Ltd and BHP Plc were traded on other trading platforms and share exchanges. Thus, the addition of claims in respect of the acquisition of a further 3.3 billion shares in BHP Ltd and BHP Plc on other trading platforms and share exchanges involves an increase of approximately 22.8% (measured by the volume of shares acquired).
19. His Honour noted (at [184]), however, that the increase in the volume of shares acquired in respect of which claims would be made does not establish the increase in value of claims made (as the value of the claim is affected by the price at which the shares were acquired, and the difference between the price paid and the "true" or "market" value in the absence of the contravening conduct).
20. His Honour also noted (at [185] and [186]) that the new claims (involving the acquisition of 3.3 billion shares) are made on behalf of both existing group members and new group members. As his Honour had found that there would be no prejudice to BHP Ltd by permitting the new claims of existing group members to date from the commencement of the proceeding, the prejudice only concerns the new claims of new group members which will only be a portion of the additional 3.3 billion shares acquired.
21. His Honour also found that BHP Ltd did not adduce evidence to show that, had it known of its potential increased exposure to claims, it would have taken a different approach in the litigation or to settlement (at [188]).

Distinguishing Ethicon Sàrl

1. The primary judge distinguished the facts of Ethicon Sàrl from the present case. His Honour noted that, in that case, there had been a series of amendments to the group definition over time that had both expanded and contracted the definition without it being clear at what point people became or ceased to be group members (at [208]). His Honour continued (at [208] and [209]): 208 … That had potentially important consequences for group members, including in respect to the suspension of limitation periods applying to group members' claims under s 33ZE of the FCA Act, and also for the respondent by way of increases and decreases in its potential aggregate liability. 209 In order to achieve some certainty, although without addressing the difficulties arising from the earlier orders which had permitted those group definition amendments and were not the subject of appeal, the Full Court ordered that the amendment to the group definition in the 5FASOC take effect from the filing of that document.
2. The primary judge explained that the Full Court's observations in that case about the power to amend a group definition must be understood in that factual context. His Honour concluded (at [214]): While the Full Court described the "default position", it expressly declined to lay down an inflexible rule in that regard. The Full Court there recognised that, depending on the circumstances, the "default position" may not be appropriate.
3. The primary judge concluded that, in this case, it was appropriate to depart from the "default position" expressed in Ethicon Sàrl (at [215]). His Honour gave seven reasons for that conclusion, although there is a degree of repetition in the seven reasons.
4. The first reason is that, in this case, the applicants are not seeking amendments to augment the class by introducing persons who are entirely new to the proceeding; instead, the applicants are seeking amendments to introduce persons into the class whom the applicants had always intended to include in the class when they commenced the proceeding but had failed to do so because of a lawyers' drafting error (at [217]).
5. The second reason is that, in this case, if the amendments do not relate to the commencement of the proceeding, existing group members will be required to undertake factually intensive, time-consuming, and (in aggregate) costly enquiries to establish whether they are, in fact, group members, and for many such persons that will be impossible to establish (at [223]).
6. The third reason is that, in ordinary inter partes litigation, the usual rule is that an amendment to correct a mistake in the name or identity of a party relates back to the commencement of the proceeding (at [225]). While this case concerns an application for leave to amend to correct a mistake in the group definition, there is nothing in the purpose and objects of Part IVA to justify treating a mistake concerning the group definition in class proceedings less beneficially than a mistake concerning a party (at [231]).
7. The fourth reason is that departure from the default position is appropriate in this case because, unless the amendments are permitted to relate back to the commencement of the proceeding, the lawyer's mistake in drafting the group definition is: (a) likely to significantly prejudice the interests of existing group members; (b) will not be in the interests of justice in the proceeding; (c) is likely to mean that the proceeding will not be conducted consistently with the overarching purpose under s 37M; and (d) gives rise to results which are antithetical to the proper operation of the regime (at [232]). His Honour concluded that the prejudice that is likely to be suffered by existing group members if the amendments are not permitted to relate back to the commencement of the proceeding is greater than and weighs more heavily in the balance than that likely to be suffered by BHP Ltd (at [235]).
8. The fifth reason is that permitting the amendments to relate back to the commencement of the proceeding best promotes the Court's overarching purpose under s 37M to facilitate the just determination of disputes according to law as quickly, inexpensively and efficiently as possible. In that respect, his Honour referred again to the difficulties that will be faced by existing group members in proving that they are group members (at [236(a)]). Also, permitting the amendments to relate back to the commencement of the proceeding is consistent with the remedial objective of ensuring that any defect is cured and that the real issues in the dispute are properly agitated. In that respect, his Honour referred again to the fact (as found) that the defect is the result of a lawyer's drafting error and that, unless the amendments are permitted to relate back, many group members are likely to face substantial difficulty in establishing that they are, in fact, group members, and many will find it impossible to do so (at [236(b)]).
9. The sixth reason is that his Honour was not persuaded that the increase in BHP Ltd's potential aggregate liability through the amendments will be as substantial as BHP Ltd suggests or material having regard to the very large claims already made in the proceeding (at [237]). Further, his Honour found that BHP Ltd's position as a result of the amendments will be no worse than if the mistake (in the drafting of the group definition) had not been made in the first place (at 238]). We understand that finding to refer to the failure of BHP Ltd to prove that it will suffer prejudice by reason of the delay in bringing the claim, as opposed to prejudice by the fact that the claim is made.
10. The seventh reason is that, if leave is not granted for the amendments to relate back to the commencement of the proceeding, the new group members will "suffer the disadvantage of being omitted from the class through a lawyer's error" (at [240]). We understand that finding to refer to the fact that the claims of new group members will be time barred unless the amendments relate back to the commencement of the proceeding. The primary judge noted that, whilst this is a relevant prejudice, he did not give it much weight in the balance (at [240]).
11. Having referred to the above matters, the primary judge concluded as follows (at [241]): Having regard to the above, I am satisfied that it is "just" to make orders pursuant to s 33K of the FCA Act, and appropriate to ensure justice is done in the proceeding to make orders pursuant to s 33ZF, to grant leave for the Group Definition Amendments to relate back to the commencement the proceeding. Such orders are also appropriate because doing so is consistent with the overarching purpose under s 37M to ensure the just determination of the proceeding, as quickly, inexpensively and efficiently as possible

Overview of BHP Ltd's grounds of appeal and Impiombato's notice of contention

1. It was common ground between the parties that the primary judge's decision granting leave to amend and making an order that the amendments take effect on and from the commencement of the proceeding (on 31 May 2018) was a discretionary decision. It follows that BHP Ltd must demonstrate error of the kind described in House v The King. It is not sufficient for this Court to conclude that it would have exercised the discretion differently had it been in the position of the primary judge.
2. BHP Ltd's grounds of appeal are stated in a somewhat verbose manner, incorporating both primary contentions and secondary contentions in the nature of particulars. The primary contentions are as follows (noting, for clarity, that references to the Appellant are to BHP Ltd and references to the Respondents are to the applicants in the proceeding): Failure to apply s 33K
3. The learned Primary Judge erred in failing to recognise that, because s 33K of the Federal Court of Australia Act 1976 (Cth) (Federal Court Act) was the sole source of the Court's power to allow an amendment to the group definition in the Consolidated Originating Application, it was not open for him to rely on s 33ZF or r 8.21 of the Federal Court Rules 2011 (Cth) as an alternative source of power to amend the group definition with retrospective effect: cf Reasons for judgment, [105], [113]-[130], [136]-[137].
4. Further or alternatively, the learned Primary Judge erred in allowing the amendment to the group definition with retrospective effect to correct a "lawyers' drafting error" (Reasons, [145]-[148], [154]) … Erroneous finding of intention and drafting error due to the Primary Judge placing undue weight upon absence of cross-examination
5. The learned Primary Judge erred placing undue weight on what he termed the "unchallenged evidence of Mr Watson, Mr Myers and Ms Lubormiska" (Reasons, [140]) and the 'election' by the Appellant not to cross-examine (Reasons, [141]-[143]), in finding that the group definition was the product of a "lawyers' drafting error" (Reasons, [145]-[148], [154]) and "that at all material times the intention of the first and second applicants, and also of MB and PFM, was to bring the proceeding on behalf of all persons who acquired an interest in BHP Shares during the Relevant Period, irrespective of the trading platform upon which that occurred" (Reasons, [151]) … Erroneous departure from Moshinsky J's decision which was subject to res judicata and issue estoppel
6. The learned Primary Judge erred in according weight to the evidence of Mr Watson and Mr Myers "that there was no good reason for them to introduce a limitation into the group definition by reference to the share trading platform upon which BHP Shares were acquired" (Reasons [149]) in circumstances where this Court had in Impiombato No 4 at [24]-[26] rejected similar evidence and held that there was "a logic to defining the class by reference to acquisition of the relevant shares on the ASX, the LSE or the JSE" which was a finding that had been determined against the Respondents and was the subject of an issue estoppel. Erroneous identification and weighing of prejudice to the Appellant
7. The learned Primary Judge erred in finding that the potential prejudice that the Appellant will suffer is "unlikely to be material in the context of the case" (Reasons [189]) …
8. Further, the Primary Judge erred in finding (Reasons, [186]), and in discounting the prejudice to the Appellant by reference to the fact, that: "[h]aving regard to the likely usage of multiple trading platforms by major Australian and overseas retail brokers and by investment banks during the Relevant Period, it seems likely that many of the 3.3 billion BHP Shares that were acquired on secondary platforms during the Relevant Period were acquired on behalf of persons who are existing group members. If that is the case, the expansion in the class and the resultant prejudice to BHP is likely to be significantly less substantial than its submissions suggest."
9. Further, the Primary Judge erred in finding that the amendment to introduce claims by "existing group members" for losses suffered as a result of acquiring BHP shares through trading on secondary platforms (in addition to existing claims for losses suffered as a result of their acquisition of BHP shares through trading on the ASX, LSE, or JSE) with retrospective effect (Loss Amendments) would impart "no prejudice to BHP" (Reasons, [255]),
10. Further, the Primary Judge erred in according any weight to the asserted prejudice to the "Excluded Shareholders" were the proposed amendments not to be made with retrospective effect (Reasons, [152]-[158]) in circumstances where there was no evidence from any "Excluded Shareholder" concerning any such prejudice. Failure to follow the Full Court's binding authority
11. Further or alternatively, the learned Primary Judge erred in failing to follow the Full Court's binding authority on the application of s 33K of the Federal Court Act in Ethicon Sàrl v Gill (2018) 264 FCR 394; [2018] FCAFC 137 (Reasons, [215]) …
12. The applicants filed a notice of contention by which they contended as follows (noting again, for clarity, that references to the Appellant are to BHP Ltd and references to the Respondents are to the applicants in the proceeding):
13. Contrary to the reasons for judgment at [59] and [156], based on the contemporaneous documents, the primary judge ought to have found that: a. at all times the Respondents had conducted the proceeding on the basis that the group members included all persons who acquired an interest in shares in the Appellant and/or BHP Group Plc during the relevant period, irrespective of the market, trading platform or means of trade through which they acquired that interest; b. the "Excluded Shareholders" (as defined in the reasons for judgment at [6]), or many of them, had reasonable grounds to believe they were group members.
14. In their written submissions, each of BHP Ltd and the applicants organised and summarised the grounds of appeal and contentions by reference to a concise statement of issues or questions. For the purposes of these reasons, the concise statements of the parties have been consolidated into the following questions, identifying the ground of appeal or contention by which the issue is raised:
15. Did the primary judge rely on an incorrect source of power to allow the amendment to the group definition and to date the amendment from the commencement of the proceeding, and thereby err in taking into account irrelevant considerations in the exercise of power (appeal grounds 1 and 2(a) and (b))?
16. Did the primary judge err in finding that the applicants and their lawyers had always intended to include as group members persons who had acquired shares in BHP Ltd and BHP Plc on trading platforms or markets other than the ASX, LSE and JSE and the lawyers had made a mistake in drafting the pleading (appeal grounds 2(c) and 3)?
17. Did the primary judge err in failing to find that the applicants had conducted the proceeding on the basis that the group members included all persons who acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period, irrespective of the market, trading platform or means of trade through which they acquired that interest (contention 1(a))?
18. Did the primary judge err in failing to find that persons who acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period on a trading platform or market other than the ASX, LSE or JSE (new group members) had reasonable grounds to believe that they were group members (contention 1(b))?
19. Did the primary judge erroneously depart from the prior decision of Moshinsky J in Impiombato No 4 at [24]-[26] (that there was a logical reason for the original description of group members having regard to the allegations concerning causation of loss) (appeal ground 4)?
20. Did the primary judge place insufficient weight on the prejudice to BHP Ltd from the loss of limitation defences (appeal grounds 5 to 7)?
21. Did the primary judge err in taking into account the prejudice to new group members if the amendments were not permitted to relate back to the commencement of the proceeding (appeal ground 8)?
22. Did the primary judge erroneously distinguish and thereby fail to follow the principles stated in Ethicon Sàrl v Gill (appeal ground 9)?

Question 1: Did the primary judge rely on an incorrect source of power and thereby err in taking into account irrelevant considerations in the exercise of power (appeal grounds 1 and 2(a) and (b))?

1. In its written submissions, BHP Ltd submitted that the primary judge erred in failing to recognise that s 33K of the FCA Act was the sole source of the Court's power to allow an amendment to the group definition in the originating application and that, as a consequence, s 33ZF of the FCA Act or r 8.21 of the FC Rules could not be relied upon as an alternative basis to amend the group definition with retrospective effect. In the course of oral argument, BHP Ltd stepped back somewhat from that submission. First, BHP Ltd acknowledged, as had been observed by the Full Court in Ethicon Sàrl, that s 33K contains an infelicity in drafting. While s 33H permits the description of group members to be contained in the originating application or the statement of claim, s 33K only refers to an amendment to the description in an originating application. Thus, the power to amend the description of group members in a statement of claim is to be found in s 33ZF (see Ethicon Sàrl at [17]). Second, BHP Ltd acknowledged that there was no question in this case that the primary judge had power to permit the amendments to be made and had power to order that the amendments take effect from the commencement of the proceeding (sourced from ss 33K and 33ZF). The principal question that arose on the appeal concerned the principles that should guide the exercise of those powers.
2. The burden of appeal grounds 1 and 2(a) and (b) was to the effect that the primary judge erred in placing reliance on r 8.21 of the FC Rules as a source of power to amend the group definition and, from that incorrect starting point, applying principles that guide the exercise of the discretionary power to amend an originating application in ordinary inter partes litigation. The argument on appeal grounds 1 and 2(a) and (b) is therefore closely connected with the argument on appeal ground 9 (the subject of question 8): whether the primary judge erroneously distinguished, and thereby failed to follow, the principles stated in Ethicon Sàrl.
3. As explained earlier, the amendments to the originating application and the statement of claim that were before the primary judge were not confined to amendments to the description of group members. They included amendments to the scope of the claims made. In particular, the amendments included new claims made on behalf of existing group members with respect to the acquisition of shares in BHP Ltd and/or BHP Plc on trading platforms or share markets other than the ASX, LSE and JSE, and also through off-market trades. The Court's power to amend the description of group members is found in ss 33K and 33ZF, while the Court's power to amend the claims made on behalf of existing group members is found in s 59(2B) and the rules made pursuant to that section, including particularly rr 8.21 (in respect of an originating application) and 16.53 (in respect of a pleading). It was therefore necessary for the primary judge to consider and apply each of the above sources of power to the different types of amendment that were sought by the applicants.
4. It can be accepted, however, that the reasons of the primary judge blurred the distinction between the amendments to the description of group members and the amendments to the scope of the claims made. The primary judge expressed the view (at [101]) that the power in s 33K does not preclude the operation of the FC Rules as a source of power to amend an originating application, relying on the decision of RD Nicholson J in Revian v Dasford Holdings Pty Ltd [2001] FCA 777 (Revian) at [9]. That proposition is expressed in an ambiguous manner. It is clearly correct that the power in s 33K does not preclude the operation of the FC Rules as a source of power to amend an originating application in relation to matters other than the description of group members. That was the point being made by RD Nicholson J in Revian. However, the reasons of the primary judge indicate that his Honour intended to convey that the power in s 33K does not preclude the operation of the FC Rules as a source of power to amend an originating application in relation to the description of group members. As submitted by BHP Ltd, the decision of RD Nicholson J in Revian does not support that proposition. Further, and more significantly, the proposition is inconsistent with the reasoning of the Full Court in Ethicon Sàrl.
5. As explained by the Full Court in Ethicon Sàrl at [49]-[52], the procedural step of amending the description of group members in a representative proceeding differs from the procedural step in ordinary inter partes litigation of adding or substituting a party to a proceeding. The Full Court stated (at [50]): By the amendment of a group definition, a new group member affected is not becoming a party, still less is the group member an existing party seeking to bring a new cause of action arising out of similar circumstances. The legal consequence is that the claim of a new group member, which claim gives rise to at least one substantial issue of law or fact with others, has become subject to the operation of the Part, subject to opt out or declassing.
6. As also explained by the Full Court (at [49]), although s 33ZG provides that nothing in Pt IVA affects the Court's powers under other provisions, Pt IVA provides its own bespoke and detailed regime and, in significant respects, the evident purpose of the Part is to displace generally understood procedures. Relevantly, amendments to the description of group members are governed by s 33K, with a supplementary source of power in s 33ZF if the description is contained in a pleading.
7. Respectfully, in so far as the primary judge's reasoning was based on the view that r 8.21 of the FC Rules was an alternative source of power to amend the description of group members, his Honour erred. However, that does not necessarily lead to a conclusion that his Honour's ultimate decision is in error (and requires appellate intervention). There is no dispute that his Honour had power to permit the amendment to the description of group members to be made, and to order that the amendment relate back to the commencement of the proceeding. The relevant question is whether his Honour erred in placing reliance on principles that guide the exercise of the power to amend under r 8.21. That question must be answered by identifying the principles that should guide a decision to permit an amendment to the description of group members and considering whether the principles that guide decisions under r 8.21 have analogical relevance.
8. Section 33K does not stipulate criteria governing the exercise of the discretion to amend the description of group members and to make ancillary orders including (implicitly) the date from which the amendments will take effect. Even in the absence of express criteria governing the exercise of the discretion, the discretion is not wholly unfettered. The discretion must be exercised judicially having regard to the nature and purpose of the power and the consequences of its exercise for the parties to the proceeding and group members who are not parties. Further, s 33K is appropriately characterised as a provision with respect to practice and procedure and is therefore subject to the considerations stated in s 37M. It follows that the discretion conferred by s 33K should be exercised in the way that best promotes the overarching purpose stated in s 37M to facilitate the just resolution of disputes according to law and as quickly, inexpensively and efficiently as possible.
9. Principles guiding the exercise of the discretion to amend a description of group members will develop on a case by case basis over time. As the High Court observed in Northern Territory v Sangare (2019) 265 CLR 164 (at [24]), the formulation of principles according to which a discretion should be exercised does not constitute a fetter upon the discretion; rather, the formulation of principles to guide the exercise of a discretion avoids arbitrariness and serves the need for consistency that is an essential aspect of the exercise of judicial power.
10. In Ethicon Sàrl, the Full Court was particularly concerned with the legal consequences of a series of amendments that had been made to the description of group members. The amendments had the effect of both expanding and contracting the group definition. The Full Court expressed the view that, while not laying down an inflexible rule, the default position should be that an amendment to the description of group members has effect from the date of the amendment (at [52]). The principal reason for the default position is the importance of class certainty in the representative proceeding regime, including the effect of s 33ZE which suspends the running of limitation periods to the claims of group members to which the proceeding relates, as discussed earlier in these reasons. As observed by the Full Court (at [51]), proceeding on the basis that an amendment to the description of group members takes effect from the date of the amendment: … prevents the topsy turvy notion that someone retrospectively becomes a group member on commencement, when the Court has thus far proceeded on the basis that they are not group members. As a matter of principle, such an approach would avoid the vice of potentially resuscitating causes of action by persons who have never sought to agitate them. It would be odd that by becoming a group member through the augmentation of a class, substantive rights were conferred on a claimant that had been either extinguished or barred by operation of statute and could not otherwise be advanced by that claimant.
11. We respectfully agree with that statement of principle. However, as stated by the Full Court, the default position is not an inflexible rule. Further, the Full Court did not suggest that the matters considered in that case were exhaustive of the matters that may be relevant to the exercise of power to permit an amendment to the group definition and to relate the amendment back to the commencement of the proceeding.
12. In the present case, the primary judge took into account the following considerations:
13. first, that the applicants and their solicitors intended from the outset to make a claim on behalf of group members in respect of the acquisition of shares in BHP Ltd and BHP Plc regardless of the trading platform or share exchange on which the acquisition occurred, but failed to give effect to that intention by mistake;
14. second, that if the amendments to the group definition do not take effect from the commencement of the proceeding, it would be necessary for existing group members to prove that they are, in fact, an existing group member by proving that they had acquired at least some shares in BHP Ltd or BHP Plc on the ASX, LSE or JSE during the relevant period and it is likely to be very difficult, time consuming and expensive (and perhaps impossible) for persons to prove which share exchange their shares were acquired on;
15. third, there would be no prejudice to BHP Ltd by permitting the new claims of existing group members to date from the commencement of the proceeding because the limitation periods applicable to those claims were likely suspended by s 33ZE;
16. fourth, although there would be some prejudice to BHP Ltd by permitting the claims of new group members to date from the commencement of the proceeding because the new claims would increase BHP Ltd's potential aggregate liability in the proceeding, the increase in BHP Ltd's potential liability would not be material having regard to the substantial quantum of the claims already made in the proceeding and, in any event, BHP Ltd did not prove that it would suffer prejudice by reason of the delay in bringing the claim, as opposed to prejudice by the fact that the claim is made.
17. The primary judge also took into account the fact that, if the amendments to the group definition do not take effect from the commencement of the proceeding, the claims made on behalf of the new group members would be barred by the applicable limitation periods. However, his Honour also concluded that this prejudice does not carry substantial weight because the new group members were not, and never had been, group members in the proceeding and they did not have reasonable grounds to believe that they were group members in the proceeding. For that reason, his Honour did not give the consideration "much weight" in the exercise of discretion.
18. A number of the above findings made by the primary judge are the subject of grounds of appeal, which are considered below. For present purposes, the question is whether the primary judge erred in taking those considerations into account. In other words, is it implicit from the purpose, scope and subject matter of the power to amend the group definition and relate the amendment back to the commencement of the proceeding that those considerations were irrelevant to the exercise of the power?
19. In its written submissions, BHP Ltd submitted that the primary judge erred in taking into account the finding of mistake on the part of the applicants' lawyers (which is the subject of appeal grounds 2(a) and (b)). It argued that the amendment of a group definition is not analogous to the amendment of the name or identity of a party in ordinary inter partes litigation, and the principles that govern amendments made to correct mistakes in the latter context have no application in the former context. In oral argument, however, BHP Ltd conceded that it was legally permissible for the primary judge to have regard to this consideration. The concession was properly made and consistent with the reasoning of the High Court in Aon Risk Services Australia Limited v Australian National University (2009) 239 CLR 175 (Aon). The purpose, scope and subject matter of the power to amend the group definition and relate the amendment back to the commencement of the proceeding does not preclude consideration of all of the circumstances that have led to the need for the amendment, including mistakes that may have been made by the applicants or their lawyers in formulating their case as a representative proceeding. The circumstance of a mistake is a factor that is relevant to the Court's assessment of whether the amendment, and whether dating the amendment from the commencement of the proceeding, are required in the interests of justice having regard to the interests of all parties and group members. That is not to suggest that mistake is a standalone basis to approve the amendment or that it is a dominant consideration. Indeed, as made clear by the Full Court in Ethicon Sàrl, an important factor is class certainty in the representative proceeding regime, including the suspension of limitation periods to the claims of group members to which the proceeding relates. Nevertheless, mistake is a factor that a court may take into account, amongst a range of factors, in exercising the discretion to allow an amendment to the group definition and to date the amendment from the commencement of the proceeding. For those reasons, the primary judge did not err in considering whether the description of group members required amendment to correct a mistake made by the applicants' lawyers. BHP Ltd's separate argument, that the primary judge erred in finding that a mistake had been made by the applicants' lawyers, is considered below.
20. BHP Ltd did not otherwise contend that the primary judge erred in taking into account the factors outlined above when exercising the discretion to allow the amendment to the group definition and to date the amendment from the commencement of the proceeding. Rather, BHP Ltd argued that his Honour erred in failing to apply the default position stated in Ethicon Sàrl. In effect, the argument is that his Honour erred in the weight attributed to each of the factors taken into account and that none of the factors outlined above outweighed the considerations that were considered dominant in Ethicon Sàrl. That argument will be considered in the context of appeal ground 9, raised by question 8.

Question 2: Did the primary judge err in finding that the applicants and their lawyers had always intended to include as group members persons who had acquired shares in BHP Ltd and BHP Plc on trading platforms or markets other than the ASX, LSE and JSE and the lawyers had made a mistake in drafting the pleading (appeal grounds 2(c) and 3)?

1. Although expressed in somewhat elliptical and verbose terms, appeal grounds 2(c) and 3 raise a confined issue: did the primary judge err in making the factual finding that the applicants and their lawyers had always intended to include as group members persons who had acquired shares in BHP Ltd and BHP Plc on trading platforms or markets other than the ASX, LSE and JSE and the lawyers had made a mistake in drafting the pleading?
2. Although the appeal is against a discretionary decision to which the principles in House v The King apply, a discretionary decision may be set aside if it is based on an error of fact. In the course of oral argument, submissions were made to the effect that the primary judge's finding was open on the evidence. That is not dispositive of appeal grounds 2(c) and 3. The appeal is not in the nature of judicial review, in which mere error of fact is insufficient to justify review. Notwithstanding that the appeal is against a discretionary decision, the appeal is by way of rehearing in which the Court is required to determine whether the primary judge's findings of fact involved error. The Court's review of the primary judge's findings of fact and inferences drawn from those facts are subject to the principles stated in Fox v Percy (2003) 214 CLR 118 and Warren v Coombes (1979) 142 CLR 531. In the present case, no witness gave oral testimony and no witness was cross-examined. The entirety of the evidence was given in written form and the hearing took a single day. In those circumstances, this Court is in as good a position as the primary judge to make findings of fact on the evidence that was adduced at the hearing.
3. On the appeal, both parties traversed the evidence bearing upon the contention, advanced by the applicants and on which the applicants bore the onus of proof, that they and their lawyers had always intended to include as group members persons who had acquired shares in BHP Ltd and BHP Plc on trading platforms or markets other than the ASX, LSE and JSE but that the lawyers had, by mistake, failed to reflect that intention when drafting the pleading. It is unnecessary to rehearse the parties' arguments, which have been taken into account in what follows. It is convenient to proceed directly to the evidence.
4. The probative evidence on the question of mistake fell into the following three categories: the history and content of the pleadings; other documents prepared by the parties in the course of the proceeding which described the claims made in the proceeding; and the evidence given by Mr Myers and Ms Lubomirska at the hearing and other statements made in affidavits tendered at the hearing. It is necessary to consider each category of evidence in turn.
5. It should be noted at the outset that neither the evidence adduced before the primary judge nor the findings of the primary judge adverted expressly to a significant factual question: whether the applicants and their lawyers were aware, at the time of the formulation of the pleading, that ordinary shares in BHP Ltd and BHP Plc were traded on trading platforms and exchanges other than the ASX, LSE and JSE. This is a significant factual question because it fundamentally alters the character of any mistake that occurred in the formulation of the group definition. If the applicants and their lawyers were so aware, and intended to include within the group definition persons who acquired shares on such trading platforms and exchanges, the failure to do so can correctly be characterised as a mistake. In the postulated circumstances, the lawyers would have failed to describe the group members in the manner that was within their express contemplation. However, if the applicants and their lawyers were only aware that the ordinary shares in BHP Ltd and BHP Plc were traded on the ASX, LSE and JSE, the formulation of the group definition by reference to the acquisition of shares on those exchanges cannot properly be described as a mistake. In hindsight, and now with knowledge of the existence of other trading platforms and exchanges on which shares in BHP Ltd and BHP Plc were traded during the relevant period, the applicants and their lawyers might describe the original formulation of the group definition as a mistake. But it was not a failure to describe the group members in the manner that was contemplated. The original formulation of the group definition would have been correctly framed having regard to the facts known to the applicants and their lawyers and the intended reach of the group definition. That is so even if, as is asserted in the evidence, the applicants and their lawyers intended to bring a proceeding on behalf of all persons who acquired an interest in shares in BHP Ltd or BHP Plc during the relevant period. If the applicants and their lawyers believed that the ordinary shares in BHP Ltd and BHP Plc were traded only on the ASX, LSE and JSE, the original formulation of the group definition was consistent with their intention, having regard to their knowledge of the share trading.

The history and content of the pleadings

1. The history and content of the pleadings has been discussed in detail earlier in these reasons. That discussion is relied upon, but will not be repeated. As earlier concluded, there is no ambiguity in those documents. The pleadings, both before and after consolidation of the original proceedings, have a singular focus on the trading of ordinary shares in BHP Ltd on the ASX and the trading of ordinary shares in BHP Plc on the LSE and JSE, and the markets for the trading of those shares on those exchanges. The defined terms "BHP ASX Shares", "BHP LSE Shares" and "BHP JSE Shares" are used consistently to refer to ordinary shares in BHP Ltd and BHP Plc traded or acquired on those exchanges. Significantly, the statement of claim makes no reference to shares in BHP Ltd or BHP Plc being acquired on any exchange, or in any manner, other than by trading on the ASX, LSE or JSE. As a consequence, the statement of claim includes no allegations concerning the causation of loss in respect of an acquisition of shares in BHP Ltd or BHP Plc being acquired on any exchange, or in any manner, other than by trading on the ASX, LSE or JSE.
2. The pleadings, both before and after consolidation of the original proceedings, are a contemporaneous record of the claims that (at the least) the lawyers acting for the applicants sought to advance on behalf of the applicants and, thereby, group members. It is extremely difficult to reconcile the applicants' contention, that they and their lawyers always intended to advance a claim in respect of shares in BHP Ltd and BHP Plc however acquired, with the content of the pleadings. The pleading does not reflect any such intention. It reflects the opposite of such an intention. It reflects a clear intention to advance a claim in respect of shares in BHP Ltd and BHP Pls acquired on the ASX, LSE or JSE. As discussed below, the applicants' evidence fails to explain how the lawyers involved in preparing the pleadings came to frame them in the manner that they did if they held the asserted intention. No explanation was proffered for the mistake beyond the assertion that a mistake was made. The most plausible explanation for the disconformity between the asserted intention and the form of the pleading is that the applicants and their lawyers were not aware that shares in BHP Ltd and BHP Plc were traded on trading platforms and exchanges other than the ASX, LSE and JSE.

Other documents prepared in the course of the proceedings

1. The second category of evidence comprises other documents prepared by the parties in the course of the proceeding which described the claims made in the proceeding. Those documents included the lawyers' retainers, the lawyers' websites that promoted the class action to potential group members and a media release issued shortly before the commencement of the Impiombato proceeding. Those documents were considered in detail by the primary judge. His Honour found that the documents relied on by the applicants were inconclusive on the question of the applicants' original intention with respect to the scope of the claims made in the proceeding (at [54] and [144]). Respectfully, a fair reading of the documents contradicts the applicants' contention.
2. It can be accepted that, in a number of documents prepared by the applicants' lawyers for the purposes of the proceeding, including documents provided to the applicants or group members (or the public more generally), the claims made in the proceeding were not described by reference to the acquisition of shares on the ASX, LSE or JSE. However, that circumstance is explicable by the nature of the documents, which comprised summaries of the claims being made. In such summaries, it is understandable that not every feature or detail of the claim was included. More significantly, none of the documents contain a statement, or a necessary implication, that the claims extended to the acquisition of shares on trading platforms or markets other than the ASX, LSE or JSE or by way of off-market transactions. Such documents are correctly described as inconclusive on the question.
3. In contrast to the inconclusive documents, it is highly significant that, on the website pages prepared by the applicants' lawyers for the purposes of explaining the class actions to potential group members, the claims made in the proceeding were described by reference to the acquisition of shares on the ASX, LSE or JSE. The primary judge recorded the following matters established by the evidence (at [43] and [48]-[50]):
4. The "bhpclassaction.com" website operated by Phi Finney McDonald described group members as follows:
   1. at 10 August 2018, as people who: … acquired shares in BHP Billiton on any of the ASX, LSE or JSE during the period from 21 October 2013 to 9 November 2015;

• 1. at 11 August 2020 and as at 1 February 2024, as people who: … acquired shares in BHP Group (formerly known as BHP Billiton), on any of the ASX, LSE or JSE during the period between 8 August 2012 to 9 November 2015...";
• 1. at 17 September 2021, as: … all investors who acquired an interest in:
• BHP Billiton Limited securities traded on the Australian Stock Exchange (ASX); and/or
• BHP Billiton Plc securities traded on the London Stock Exchange (LSE) and/or the Johannesburg Stock Exchange (JSE)"; and
• 1. at 3 December 2022 and as at 1 February 2024, as: …all eligible shareholders who from 8 August 2012 through 9 November 2015 inclusive (claim period) acquired an interest in:
• BHP Billiton Limited securities traded on the Australian Stock Exchange (ASX); and/or
• BHP Billiton Plc securities traded on the London Stock Exchange (LSE) and/or the Johannesburg Stock Exchange (JSE).

1. From February 2020 to 1 February 2024 (the date of Ms Tran's affidavit), the page of Maurice Blackburn's website concerning the class action (entitled "BHP class action") contained the following statements: BHP class action On 31 August 2018 Maurice Blackburn filed a class action on behalf of shareholders of BHP Billiton Limited (ASX:BHP) and BHP Billiton Plc (listed on the Johannesburg and London stock exchanges) who suffered losses due to the share price fall following the Fundão Dam collapse on 5 November 2015. … The class action covers eligible shareholders who entered into a contract to acquire an interest in ordinary shares on any of the three above-mentioned stock exchanges between 27 August 2014 and 9 November 2015 inclusive.
2. From late July or early August 2019 to 1 February 2024 (the date of Ms Tran's affidavit), the Maurice Blackburn website incorporated a portal for group members to register their claims. At the bottom of the page entitled "BHP class action", a "Sign up now" button appeared, which linked to a "landing page" for registration. The landing page for registration relevantly said: Retain Maurice Blackburn in the BHP Class Action Maurice Blackburn is conducting a class action on behalf of shareholders of BHP Group Limited (ASX: BHP) and BHP Group Plc (listed on the Johannesburg and London stock exchanges) who suffered loss due to the share price fall following the Fundão Dam collapse on 5 November 2015 (BHP shareholders). … Who is eligible to participate Participation is open to persons who acquired an interest in fully paid ordinary shares in BHP during the period between 8 August 2012 and 9 November 2015 (inclusive). We ask, however, that you submit your trading data up until 30 November 2015 if available. The BHP class action also extends to claims of shareholders of BHP Group Plc who acquired shares on the Johannesburg Stock Exchange and/or the London Stock Exchange during the relevant period. If you hold shares that were acquired on either exchange during 8 August 2012 and 9 November 2015, we welcome you to retain us, specifying which stock exchange they were acquired on. The landing page further noted that readers "will also be asked to provide details about the claimant's shareholding(s), including… the stock exchange upon which the shares were purchased, being the Australian Stock Exchange (ASX), the Johannesburg Stock Exchange (JSE) or the London Stock Exchange (LSE)."
3. The foregoing statements are a reasonably accurate reflection of the scope of the claims made in the pleadings. They convey that the claim concerns losses arising from the acquisition of shares in BHP Ltd on the ASX and BHP Plc shares on the LSE and JSE during the relevant period. As is the case with the pleadings, it is extremely difficult to reconcile the applicants' contention, that they and their lawyers always intended to advance a claim in respect of shares in BHP Ltd and BHP Plc however acquired, with the statements made on the lawyers' websites with respect to the claims made in the proceeding. Again, the most plausible explanation is that the applicants and their lawyers were not aware that shares in BHP Ltd and BHP Plc were traded on trading platforms and exchanges other than the ASX, LSE and JSE.

The lawyers' evidence

1. The third category of evidence comprises the evidence given by Mr Myers and Ms Lubomirska at the hearing and other statements made in affidavits tendered at the hearing. For reasons that will be explained, the evidence was unsatisfactory in many respects and does not support a finding that, at the time the pleadings were prepared, the applicants and their lawyers were aware that shares in BHP Ltd and BHP Plc were traded on trading platforms or exchanges other than the ASX, LSE and JSE and intended to make a claim in respect of such acquisitions.

Mr Watson's evidence

1. It is convenient to begin with the evidence of Mr Watson who was, at the time of the preparation of the pleadings, a principal of Maurice Blackburn. Maurice Blackburn initially represented Klemweb in the Klemweb proceeding. After the consolidation of the Impiombato and Klemweb proceedings, Maurice Blackburn represented both applicants. Mr Watson's affidavit evidence was prepared for the purposes of the application before Moshinsky J, not for the amendment application before Murphy J. On 13 November 2023, and before the amendment application was made, Mr Watson was appointed as a judge of the Supreme Court of Victoria. No doubt that explains the applicants' decision not to call Mr Watson as a witness on the amendment application but to tender his earlier affidavits. The practical consequence was that the evidence contained in those affidavits was not able to be tested by cross-examination.
2. In his affidavit dated 15 October 2023, Mr Watson stated that he had been the head of Maurice Blackburn's national class actions practice since June 2011. However, he did not identify his involvement in either the Klemweb proceeding (in its original form) or the consolidated proceeding, including the preparation of the pleadings. As noted earlier, the Klemweb pleading was certified by Ms Dellavedova, although the consolidated pleading was certified by Mr Watson.
3. Paragraph 18 of the affidavit dated 15 October 2023 contains the following statements: At all times since the commencement of this proceeding, the Applicants' intention was, and remains, to bring a proceeding on behalf of all persons who acquired an interest in shares in the Respondent or BHP Plc during the Relevant Period. On the Applicants' case, all such persons would have suffered loss or damage by, or as a result of, the Respondent's conduct alleged in the ACSOC. There was and is no reason why the Applicants would exclude from the proceeding persons who acquired shares in the Respondent or BHP Plc through platforms other than the ASX, LSE or JSE. It is my view that the description of the group members in the COA and ACSOC reflects that intention.
4. The first sentence merely asserts a conclusion about the intention of the applicants. It begs many questions. First, on what basis was Mr Watson aware of the intention of Mr Impiombato with respect to the claims made in the proceeding before the consolidation of the proceedings when Maurice Balckburn began representing Mr Impiombato? Second, in what manner, and at what time, did Klemweb inform Mr Watson of its intention? Third, what did the applicants mean by saying that they intended to bring a proceeding on behalf of all persons who acquired an interest in shares in BHP Ltd or BHP Plc during the relevant period? In particular, were the applicants aware that shares in BHP Ltd and BHP Plc could be acquired on trading platforms or exchanges other than the ASX, LSE or JSE, or in off-market transactions? In what sense did the applicants consider that persons who acquired shares in such manner might have suffered loss in the same manner as persons who acquired shares on the ASX, LSE or JSE? The second sentence adds nothing of evidentiary value. The third sentence is mere argument, and is an argument that was rejected by Moshinsky J and which we also reject. The fourth sentence expresses an opinion about the pleading that was rejected by Moshinsky J and which we also reject.
5. Paragraph 19 of the affidavit dated 15 October 2023 contains the following statement: At all times, the Applicants have conducted the proceeding on the basis that the group members included all persons who had acquired an interest in shares in the Respondent and BHP Plc during the Relevant Period.
6. That is an assertion that is not supported by the evidence. Justice Murphy found that the contemporaneous documents are inconclusive (at [59]). As noted above, while a number of the contemporaneous documents are inconclusive, the contents of Maurice Blackburn's website contradicts the assertion, not to mention the contents of the pleading.
7. It is of some significance that Mr Watson did not state in his affidavit, in clear terms, that at the time of preparing the consolidated pleading he intended to include a claim in respect of shares in BHP Ltd and BHP Plc acquired on trading platforms and exchanges other than the ASX, LSE or JSE. The fourth sentence of para 18, reproduced above, is not to that effect. That sentence is merely a statement of Mr Watson's opinion, held at the time that he made his affidavit, about the consolidated pleading. There is no statement that Mr Watson was aware of and had in mind, at the time of preparing the consolidated pleading, that shares in BHP Ltd and BHP Plc were traded on trading platforms or exchanges other than the ASX, LSE or JSE, or through off-market transactions, and that he intended to make a claim in respect of all such acquisitions during the relevant period.
8. The foregoing is the totality of the relevant evidence given by Mr Watson. It has little, if any, probative value in supporting a finding of relevant mistake. It was not prepared for the purposes of the amendment application and it is stated at such a high level of generality that it can be given no material weight.

Ms Lubomirska's evidence

1. Ms Lubomirska has been a Special Counsel at Maurice Blackburn since 2015. In her affidavit dated 29 February 2024, Ms Lubomirska deposed that she has been involved in the proceeding since the consolidation of the Impiombato and Klemweb proceedings. Ms Lubomirska did not state, however, that she had any involvement in the preparation of the consolidated pleading, far less that she intended the pleading to include a claim in respect of the acquisition of shares in BHP Ltd and BHP Plc on trading platforms or exchanges other than the ASX, LSE or JSE, or through off-market transactions.
2. Instead, Ms Lubomirska deposed to information conveyed to her by David Webb, who is a director of Klemweb. Although not stated expressly, we infer that the information was conveyed to Ms Lubomirska shortly before the making of her affidavit (on 29 February 2024) and for the purposes of the affidavit. The information concerns one or more conversations that occurred between Mr Webb and Ms Dellavedova prior to the commencement of the Klemweb proceeding, which was on 31 August 2018. The most relevant aspects of the evidence were as follows: 10 I conferred with Mr Webb regarding his intentions and his understanding of the scope of group membership and claims to be encompassed in the class action. Mr Webb informed me, and I believe that, prior to the commencement of the Klemweb proceedings, he spoke with Brooke Dellavedova (who was then a principal of MB) and was provided with an explanation of the class action and the role of a representative applicant. He understood from those discussions that: (a) he is a part of a group of people and, as the representative applicant, he would represent that group to bring an action on their behalf; (b) the people who were in the group that he would represent were the other BHP Ltd shareholders who bought their shares in BHP in a particular period of time; (c) the group that he would represent may also encompass shareholders of the UK BHP company (i.e. BHP Plc) who bought BHP Plc shares in that period of time, not only the Australian BHP company (i.e. BHP Ltd); (d) the claim would encompass anyone who bought shares in BHP Ltd or BHP Plc (BHP) (in a particular period). 11 Mr Webb also informed me, and I believe, that he did not understand that the claim would be limited in some way based on the exchange, platform or means through which the trades occurred.
3. Little weight can be given to that evidence. First, the evidence concerns one or more conversations that occurred between Mr Webb and Ms Dellavedova more than 5 years previously in circumstances where it appears that no contemporaneous records of the conversations were made (none was adduced in evidence). Second, the evidence is properly characterised as self-serving and, given the circumstances in which the evidence was given, it is very likely that Mr Webb's recollection has been coloured by the current interlocutory disputes. Third, the evidence is vague in important respects and begs numerous questions. Whilst Mr Webb informed Ms Lubomirska that he did not understand that the claim would be limited in some way based on the exchange, platform or means through which the share trades occurred, there is no evidence that, at the time the pleadings were prepared, Mr Webb was aware of the existence of other trading platforms or exchanges or turned his mind to such matters. Nor is there any evidence that he discussed such matters with Ms Dellavedova or gave such instructions. It should also be noted that there was no opportunity for BHP Ltd to cross-examine Mr Webb about those matters because Mr Webb was not called as a witness. Rather, Ms Lubomirska gave hearsay evidence about those matters.
4. In her affidavit, Ms Lubomirska attempted to support Mr Webb's evidence by reference to a limited number of written communications passing between Ms Dellavedova and Mr Webb. The written communications do not advance the applicants' position on this issue. Like other documents referred to earlier, the communications contain a summary of the proposed claims to be made and are silent (and therefore inconclusive) on the question whether it was intended that the claims would extend to the acquisition of shares in BHP Ltd and BHP Plc on trading platforms and exchanges other than the ASX, LSE and JSE.
5. Assessing Ms Lubomirska's evidence as a whole, it has little if any probative weight on the question whether the applicants intended to advance a claim in respect of shares in BHP Ltd and BHP Plc that were acquired on trading platforms or exchanges other than the ASX, LSE and JSE. Additionally, the evidence provides no support for the applicants' contention that Maurice Blackburn intended to advance such a claim (in the sense of the claim being in express contemplation) but failed to do so by mistake.

Mr Phi's evidence

1. As noted earlier, Mr Myers tendered in evidence (by way of an annexure to his affidavit) an affidavit made on 16 October 2018 by Mr Phi who, at that time, was the Managing Partner and a principal of the firm Phi Finney McDonald. The affidavit was made for the purposes of resolving multiplicity issues arising out of the commencement of the Impiombato and Klemweb proceedings. Mr Phi certified the original pleading in the Impiombato proceeding and the consolidated pleading (together with Mr Watson) following the consolidation of the Impiombato and Klemweb proceedings.
2. In that affidavit, Mr Phi accurately described the claims made in the proceeding in the following terms: On 31 May 2018, the Applicant filed the Statement of Claim to commence a representative proceeding against BHP Ltd pursuant to Part IVA of the Federal Court of Australia Act 197 6 (Cth) on its own behalf and on behalf of an open class of persons (Group Members), who, inter alia: (a) during the period from 21 October 2013 until the close of trade on 9 November 2015 inclusive (Relevant Period), acquired an interest in: (i) fully paid ordinary shares in BHP Ltd on the ASX; and/or (ii) fully paid ordinary shares in BHP Plc on the LSE; and/or (iii) fully paid ordinary shares in BHP Plc on the JSE; and (b) are alleged to have suffered loss and damage by or resulting from the conduct alleged in the Statement of Claim.
3. There is no suggestion in Mr Phi's statement that the claims included acquisitions of shares on other trading platforms or exchanges, or off-market transactions, or that Mr Impiombato or Phi Finney McDonald intended such acquisitions to be included. Mr Phi's statement has significant probative value on the question to be determined. Mr Phi was responsible for the preparation of the pleading in the Impiombato proceeding and the statement was made shortly after the pleading was prepared. It is also significant that Mr Phi did not give evidence in the amendment application seeking to qualify or explain the foregoing evidence.

Mr Myers' evidence

1. As noted earlier, Mr Myers is a Principal Lawyer in the firm Phi Finney McDonald. In his affidavits, Mr Myers did not provide any details of his position within the firm at the time of preparation of the Impiombato pleading or the consolidated pleading, and he did not give evidence that he played any role in their preparation. It can be inferred from Mr Myers' affidavit dated 5 December 2023 that he had at least some involvement in the proceeding at or around its commencement because he assisted Mr Finney in collating information for an affidavit made by Mr Finney on 13 July 2018, being the number of shares held by group members who had entered into funding agreements with the litigation funder supporting the Impiombato proceeding (see para 27). That can be regarded as an administrative task. In his affidavit, Mr Myers proffers the statement that, in collating that information, "I did not exclude persons who acquired shares, or shares acquired, through trades other than on the ASX, LSE and/or JSE". Significantly, Mr Myers does not state that he was aware, at that time, that shares in BHP Ltd and BHP Plc were able to be acquired on trading platforms or exchanges other than the ASX, LSE or JSE, far less that Phi Finney McDonald intended to bring claims in respect of such acquisitions.
2. At para 23 of his affidavit dated 5 December 2023, Mr Myers stated: When commencing this Proceeding and the Klemweb Proceeding, the Applicants' intention was, and remains, to bring proceedings on behalf of all persons who acquired an interest in shares in BHP Ltd and/or BHP Plc during the Relevant Period, irrespective of the market or platform or means of trade through which those trades occurred.
3. That evidence is phrased in almost identical language to the evidence given by Mr Watson in his earlier affidavit dated 15 October 2023, reproduced above. The observations made in respect of Mr Watson's evidence apply equally, or perhaps with even more force, to Mr Myers' evidence. Unlike Mr Watson, there is no evidence that Mr Myers had any supervisory role with respect to the proceeding at the time the pleadings were prepared, or any direct contact with the applicants. It is apparent that both Mr Phi and Mr Finney had the supervisory role, but neither of them gave evidence. As is the case with Mr Watson's evidence, Mr Myers' evidence merely asserts a conclusion about the intention of the applicants. It begs many questions. First, on what basis was Mr Myers aware of the intention of Klemweb with respect to the claims made in the Klemweb proceeding before the consolidation of the proceedings when Phi Finney McDonald began representing Klemweb? Second, in what manner, and at what time, did Mr Impiombato inform Mr Myers of his intention? Third, what did the applicants mean by saying that they intended to bring a proceeding on behalf of all persons who acquired an interest in shares in BHP Ltd or BHP Plc during the relevant period? In particular, were the applicants aware that shares in BHP Ltd and BHP Plc could be acquired on trading platforms or exchanges other than the ASX, LSE or JSE, or in off-market transactions? In what sense did the applicants consider that persons who acquired shares in such manner might have suffered loss in the same manner as persons who acquired shares on the ASX, LSE or JSE?
4. Mr Myers purports to support the assertion in para 23 of his affidavit by noting that the particulars to the group definitions in the original pleadings contained particulars of the applicants' trades in BHP Ltd shares during the relevant period, but did not contain any information about the trading platform used by the applicants to trade in shares in BHP Ltd. It is significant, however, that Mr Myers did not give evidence that the applicants acquired shares in BHP Ltd in any market or on any platform other than the ASX, and there is no evidence to suggest that the applicants or Phi Finney McDonald ever turned their minds to the possibility that shares in BHP Ltd and in BHP Plc were able to be acquired on trading platforms or markets other than the ASX, LSE and JSE.
5. At para 26 of his affidavit dated 5 December 2023, Mr Myers stated: Furthermore, at all times since commencing the proceedings, the Applicants have conducted them on the basis that the group members included all persons who had acquired an interest in fully paid up ordinary shares in BHP Ltd and/or BHP Plc during the Relevant Period. …
6. Again, that evidence is phrased in almost identical language to the evidence given by Mr Watson in his earlier affidavit dated 15 October 2023, reproduced above. The observations made in respect of Mr Watson's evidence apply equally, or perhaps with even greater force, to Mr Myers' evidence. It is an assertion that is not supported by the evidence. The primary judge found that the contemporaneous documents are inconclusive (at [59]). While a number of the contemporaneous documents are inconclusive, the contents of Phi Finney McDonald's website contradict the assertion. Further, and even more powerfully, the contents of the original Impiombato pleading wholly contradict the assertion. As noted earlier in these reasons, the language of the original Impiombato pleading could not be clearer in confining the claims to the acquisition of shares in BHP Ltd on the ASX and the acquisition of shares in BHP Plc on the LSE and JSE. It is clear from Mr Phi's affidavit dated 16 October 2018 that he understood the pleading in those terms.
7. At para 53 of his affidavit dated 5 December 2023, Mr Myers stated: To the extent that the Applicants failed to execute their intention, deposed to at paragraph 23 above, to include all persons who acquired shares in BHP Ltd and BHP Plc in the description of the group members in the originating applications and pleadings filed in the proceedings, that was an inadvertent mistake in the drafting, which the Applicants now seek to correct by their amendment application.
8. The bald assertion made by Mr Myers that the Impiombato and consolidated pleadings were prepared in a manner that involved an "inadvertent mistake" has no probative value. There is no evidence that Mr Myers had any involvement in the preparation of the pleadings. Mr Myers provides no specific evidence as to: the source of his information concerning the mistake; the person or persons who made the mistake; or how the mistake came to be made. The evidence is contradicted by the evidence of Mr Phi (who certified the pleadings) in his affidavit dated 16 October 2018.
9. At para 27 of his affidavit dated 26 February 2024, Mr Myers stated: I understood when the Proceeding was commenced, and at all times since, that the references to the ASX, LSE and JSE in the context of the descriptions of the group members and other parts of the pleadings reflected the dual-listed structure of BHP Ltd and BHP Plc, and referred to shares on the ASX, LSE and JSE in the sense of being listed or quoted on those exchanges. I did not understand the references to the ASX, LSE and JSE to introduce any limitation on, or criterion for, group membership such that a person's acquisition of shares in BHP Ltd or BHP Plc had to occur through trading on those exchanges.
10. Again, that evidence has little probative value on the question to be determined. Leaving aside the facts that there is no evidence that Mr Myers was involved in preparing the pleadings and that Mr Phi's evidence negatives any suggestion that Mr Phi was mistaken about the meaning and effect of the pleading, what is absent is any evidence from Mr Myers that he was aware of the existence of other trading platforms and exchanges on which shares in BHP Ltd and BHP Plc were traded and that he believed that the pleading advanced a claim in respect of shares acquired in that manner. The absence of such evidence is telling, particularly in circumstances where the pleading makes no reference to any such trading platforms and exchanges and, as explained above, is wholly focussed on the acquisitions of shares on the ASX, LSE and JSE.
11. At para 42 of his affidavit dated 26 February 2024, Mr Myers stated: I believe, based on information from Ms Lubomirska and Ronald Koo, now a Principal of MB, that at all times since prior to the commencement of the Klemweb Proceeding, and following consolidation, MB intended to bring the proceedings on behalf of all persons who acquired shares in BHP Ltd and/or BHP Plc during the Relevant Period, irrespective of the platform or other means of trading through which those shares were acquired. I further believe, based on information from Ms Lubomirska and Mr Koo, that at all times they understood that the references to the ASX, LSE and JSE in the context of the descriptions of the group members reflected the dual-listed structure of BHP Ltd and BHP Plc, and not that group membership was restricted to persons who acquired shares on those specific exchanges.
12. By that paragraph, Mr Myers purports to give hearsay evidence about Maurice Blackburn's intentions with respect to the claims made in the original Klemweb proceeding and the consolidated proceeding. One of many striking aspects of that evidence is that Ms Lubomirska made an affidavit three days later (on 29 February 2024) which does not contain evidence to that effect. Furthermore, despite referring to Mr Myers' affidavit dated 26 February 2024, Ms Lubomirska does not refer to or confirm Mr Myers' evidence set out above. As noted earlier, Ms Lubomirska's evidence was confined to the intention of Klemweb in relation to the claims made in the proceeding, and Ms Lubomirska did not purport to give any evidence with respect to the intention of Maurice Blackburn. The inconsistency between the evidence of Ms Lubomirska and Mr Myers in that respect is unexplained. No evidence was given with respect to Mr Koo's involvement in the preparation of the pleadings and the source of any knowledge he might have had with respect to Maurice Blackburn's intention regarding the claims made in the proceeding. Ultimately, the same problems underlie the foregoing evidence. Absent is any evidence that relevant lawyers at Maurice Blackburn were aware of the existence of other trading platforms and exchanges on which shares in BHP Ltd and BHP Plc were traded and believed that the pleading advanced a claim in respect of shares acquired in that manner.
13. Finally, at para 7 of his affidavit dated 29 February 2024, Mr Myers stated: I am informed by Mr Impiombato, that it was his intention to bring proceedings on behalf of a group comprising all people who bought shares in BHP Ltd and/or BHP Plc (BHP).
14. That evidence suffers from the same deficiencies as discussed above in connection with the evidence given by Ms Lubomirska about Mr Webb's intention. The evidence is properly characterised as self-serving and, given the circumstances in which the evidence was given, it is very likely that Mr Impiombato's recollection has been coloured by the current interlocutory disputes. Further, the evidence is vague and begs numerous questions. Whilst Mr Impiombato informed Mr Myers that that it was his intention to bring proceedings on behalf of all people who bought shares in BHP Ltd and/or BHP Plc, there is no evidence that, at the time the pleadings were prepared, Mr Impiombato was aware of the existence of trading platforms or exchanges other than the ASX, LSE and JSE or turned his mind to such matters. Nor is there any evidence that he discussed such matters with anyone at Phi Finney McDonald or gave instructions in relation to such matters. It should also be noted that there was no opportunity for BHP Ltd to cross-examine Mr Impiombato about those matters because he was not called as a witness. Rather, Mr Myers gave hearsay evidence about those matters.

Consideration of the evidence as a whole

1. Taking the evidence adduced on the amendment application as a whole, the weight of evidence negatives a finding that the applicants and their lawyers, being aware that shares in BHP Ltd and BHP Plc were traded on trading platforms or markets other than the ASX, LSE and JSE, intended to include as group members persons who had acquired shares on such platforms or exchanges and the lawyers had made a mistake in drafting the pleading. The applicants' evidence in support of the contention was unsatisfactory in many respects and of little weight, whilst the history and the content of the pleadings and the pages of the websites of Phi Finney McDonald and Maurice Blackburn contradict the applicants' contention. Respectfully, the primary judge erred in making the factual finding sought by the applicants.
2. The primary judge made the finding sought by the applicants on the basis of the evidence given by Mr Watson, Ms Lubomirska and Mr Myers. His Honour characterised the evidence as unchallenged (at [140]), as credible (at [144]) and having probative value (at [140]), and placed considerable emphasis on the fact that BHP Ltd elected not to cross-examine those "witnesses" (at [141]-[143]). The primary judge also referred (at [143]) to the principle that, as a general proposition, unchallenged evidence ought be accepted unless it is inherently incredible or contradicted by facts otherwise established on the evidence, citing Precision Plastics Pty Ltd v Demir (1975) 132 CLR 362 at 370-371 (Gibbs J, with whom Stephen and Murphy JJ agreed).
3. Contrary to the primary judge's conclusion, there was no opportunity for BHP Ltd to cross-examine Mr Watson, and there could be no utility in cross-examining Ms Lubomirska or Mr Myers about the hearsay evidence they gave concerning the intentions of the applicants at the time the pleadings were prepared. While it would have been possible for BHP Ltd to cross-examine Mr Myers about his statements concerning his understanding of the pleadings and the intentions of Phi Finney McDonald, it was unnecessary for BHP Ltd to do so given the deficiencies in that evidence. As recently observed by the Full Court in Singtel Optus Pty Ltd v Robertson [2024] FCAFC 58 (at [66]), a court is not obliged to treat the evidence of a witness as determinative merely because the witness is not cross-examined. BHP Ltd's election not to cross-examine did not increase the probative value of evidence that inherently lacked probative value.
4. For the reasons explained above, we have reached a different conclusion to the primary judge with respect to the probative value of the evidence of Mr Watson, Ms Lubomirska and Mr Myers. In large part, this is due to the absence of any evidence that the applicants and their lawyers were aware, at the time of the formulation of the pleading, that ordinary shares in BHP Ltd and BHP Plc were traded on trading platforms and exchanges other than the ASX, LSE and JSE. In the absence of any probative evidence to that effect, the statement that the applicants and their lawyers always intended to bring a claim in respect of all acquisitions of shares in BHP Ltd and BHP Plc takes on a different complexion. Having regard to the totality of the evidence (the history and the content of the pleadings, the pages of the websites of Phi Finney McDonald and Maurice Blackburn referred to earlier, and the statements made by Mr Phi in his affidavit dated 16 October 2018), the most likely explanation for the formulation of the group definition is that the applicants and their lawyers were only aware of the trading of shares on the ASX, LSE and JSE.
5. It can be accepted that, today, the applicants, their lawyers and probably their litigation funders consider that they made a mistake in the drafting of the original pleadings and the consolidated pleading by not including a claim in respect of the acquisition of shares in BHP Ltd and BHP Plc however the acquisition occurred. In hindsight, and with an awareness of the other trading platforms and exchanges on which the shares may have been acquired, they no doubt consider that they ought to have included such claims and believe that they made a mistake in not doing so. However, that is a different type of mistake to the one asserted by the applicants on the amendment application.
6. One final evidentiary matter should be addressed. The primary judge considered that the evidence given by Mr Watson and Mr Myers was buttressed by their statements that there was no reason why the applicants would exclude from the proceeding persons who acquired shares in BHP Ltd or BHP Plc through trading platforms or exchanges other than the ASX, LSE or JSE. The primary judge reasoned (at [149]-[150]): 149 Fourth, my view regarding the sufficiency of the applicants' evidence of intention is buttressed by the evidence of Mr Watson and Mr Myers that there was no good reason for them to introduce a limitation into the group definition by reference to the share trading platform upon which BHP Shares were acquired. I accept that evidence. To my knowledge, until this case, there has never been an Australian securities class action in which the applicant limited the group definition in respect of shares quoted on the ASX by reference to the trading platform upon which the share trades were executed. That is for good reason. Any such limitation would be likely to introduce unnecessary uncertainty and complexity into a group definition; give rise to a need to undertake factually intensive enquiries by persons to ascertain whether or not they are group members; and to create difficulties in establishing who is, in fact, a group member. Such difficulties and uncertainty are quite undesirable in a proceeding under Part IVA, and I can see no logical reason for law firms experienced in securities class actions like MB and PFM to have deliberately drafted the group definition with such a limitation. 150 I note that is different view to the view Moshinsky J took in Impiombato No 4 (at [26]). His Honour concluded that, having regard to the causation pleading, there appeared to be a logic to defining the class by reference to acquisition of the relevant shares on the ASX, the LSE or the JSE. In my view the causation pleading is grounded in the proposition that the price of shares on one exchange was influenced by material information concerning BHP which was disclosed on the other exchanges. I do not consider that required that group membership be defined by reference to the acquisition of shares on either the ASX, the LSE or the JSE.
7. In Impiombato No 4 at [24], Moshinsky J noted the following matters concerning the pleading of causation of loss: The context of the group member definition in the statement of claim includes the rest of the pleading. In my view, a consideration of the balance of the pleading supports BHP Ltd's interpretation. The pleading contains a definition of the BHP ASX Share Market (in paragraph 5(c)), the BHP LSE Share Market (in paragraph 8(a)) and the BHP JSE Share Market (in paragraph 8(b)). These markets then form the basis for a substantial part of the causation pleading in section L of the statement of claim (paragraphs 68-80). In broad terms, it is alleged that the pleaded contraventions caused the price at which the relevant shares traded on the ASX, the LSE and the JSE to be higher than their true value or the market price that would have prevailed but for the contraventions. These pleadings appear to be predicated on group members having purchased their shares on one of those exchanges. No other platforms are pleaded or referred to.
8. Then, at [26], Moshinsky J expressed the following view: Insofar as the applicants submit that it would make no sense to carve out persons who acquired their shares on other trading platforms, I do not accept that submission. Having regard to the causation pleading referred to above, there does appear to be a logic to defining the class by reference to acquisition of the relevant shares on the ASX, the LSE or the JSE.
9. By appeal ground 4, BHP Ltd contends that it was not open to the primary judge to diverge from Moshinsky J on the above issue: whether it was logical for the applicants and their lawyers to frame their claim by reference to the acquisition of shares in BHP Ltd and BHP Plc on the ASX, LSE and JSE. For the reasons given below (see question 5), that contention should be rejected. It is therefore necessary to address the primary judge's reasoning that this consideration bolstered the evidence given by Mr Watson and Mr Myers.
10. Contrary to the view formed by the primary judge, this consideration carries little weight. There are two principal reasons for that conclusion, which are interrelated.
11. The first reason is that the consideration assumes that, at the time the pleadings were prepared, the applicants and/or their lawyers were aware that shares in BHP Ltd and BHP Plc could be acquired on trading platforms and exchanges other than the ASX, LSE and JSE and, furthermore, that the prices at which trades were conducted on such trading platforms or exchanges were affected by the disclosure of information on the ASX, or at least by the prices at which trades were conducted on the ASX, LSE and JSE. That assumption cannot be made. As already noted, no evidence was adduced to that effect. Further, and as noted earlier, in his affidavit dated 15 October 2023, Mr Watson deposes that: "In preparation for the hearing on 18 October 2023, I instructed Samuel Habteslassie, an employee solicitor of [Maurice Blackburn], to undertake research relevant to the manner in which shares in ASX-listed entities … may be acquired through the Chi-X platform". The implication of that statement is that no such research had previously been undertaken by Maurice Blackburn in connection with the proceeding. That is a surprising circumstance if Maurice Blackburn was aware of the Chi-X platform and intended to extend the claims in the proceeding to shares acquired on that platform.
12. The second reason is that the consideration cannot be reconciled with the pleading of causation of loss, as observed by Moshinsky J. The primary judge diverged from Moshinsky J on that point, expressing the view (at [150]) that "the causation pleading is grounded in the proposition that the price of shares on one exchange was influenced by material information concerning BHP which was disclosed on the other exchanges". With respect, that statement fails to acknowledge that the pleading referred expressly to the acquisition of shares on three specific exchanges, being the ASX, LSE and JSE, and alleged that the prices on the LSE and JSE were influenced by information disclosures made on the ASX. There was no allegation concerning the acquisition of shares on any other trading platform or exchange, nor any allegation that information disclosures made on the ASX influenced the prices on any other trading platform or exchange.
13. It follows that appeal grounds 2(c) and 3 should be upheld. There is no doubt that the primary judge's finding, that the applicants and their lawyers had always intended to include as group members persons who had acquired shares in BHP Ltd and BHP Plc on trading platforms or markets other than the ASX, LSE and JSE and that the lawyers had made a mistake in drafting the pleading, was material to his Honour's decision in granting the application to amend and relating the amendment back to the commencement of the proceeding. It will therefore become necessary for this Court to re-exercise the discretionary power with respect to the amendment.

Question 3: Did the primary judge err in failing to find that the applicants had conducted the proceeding on the basis that the group members included all persons who acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period, irrespective of the market, trading platform or means of trade through which they acquired that interest (contention 1(a))?

1. On the appeal, the applicants advanced the contention that the primary judge erred in failing to find that the applicants had conducted the proceeding on the basis that the group members included all persons who acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period, irrespective of the market, trading platform or means of trade through which they acquired that interest. However, the contention was not pressed with any enthusiasm. In their written submissions, the applicants devoted a single paragraph to the contention.
2. The primary judge concluded (at [59]) that the contemporaneous documents are inconclusive as to whether the applicants conducted the proceeding on the basis that the group members included all persons who acquired shares in BHP Ltd and BHP Plc during the relevant period. His Honour considered that the documents pointed both ways. For the reasons expressed in relation to the preceding question, the contemporaneous documents do not point in different directions. There is not a single document that states expressly that group members are persons who acquired an interest in shares in BHP Ltd and/or BHP Plc during the relevant period, irrespective of the market, trading platform or means of trade through which they acquired that interest. Rather, certain of the documents express the description of group members, and the claims made in the proceeding, in a summary or shorthand manner which omits reference to the acquisition of shares on the ASX, LSE or JSE. They do not provide any material support for the applicants' contention. The documents which express the description of group members, and the claims made in the proceeding, in a more complete manner, including particularly the website pages of Phi Finney McDonald and Maurice Blackburn, include express references to the acquisition of shares on the ASX, LSE or JSE.
3. The applicants failed to demonstrate any error in the conclusion of the primary judge on this issue. It follows that contention 1(a) should be rejected.

Question 4: Did the primary judge err in failing to find that persons who acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period on a trading platform or market other than the ASX, LSE or JSE (new group members) had reasonable grounds to believe that they were group members (contention 1(b))?

1. On the appeal, the applicants also advanced the contention that the primary judge erred in failing to find that persons who acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period on a trading platform or market other than the ASX, LSE or JSE (new group members) had reasonable grounds to believe that they were group members. Again, however, the contention was not pressed with any enthusiasm. In their written submissions, the applicants devoted a single paragraph to the contention.
2. The primary judge concluded (at [156]) that he was not satisfied that the new group members had reasonable grounds to believe that they were group members. His Honour again described the documents that were made available to potential group members as conveying different things. Respectfully, and as stated earlier, some of the documents were expressed in a summary form whilst other documents stated clearly that group members are persons who acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period on the ASX, LSE or JSE. The primary judge also took account (at [157] and [158]) of the facts that, as at 25 October 2018, approximately 30,000 BHP shareholders had retained either Phi Finney McDonald or Maurice Blackburn to act for them in the case, but the applicants did not adduce evidence from a single person to the effect that:
3. they believed that they were group members in the proceeding and, for that reason, they did not take any steps to vindicate or preserve their rights against BHP Ltd outside of the proceeding; or
4. had they known they were outside of the class in the proceeding they would have taken steps to vindicate their rights against BHP Ltd through an individual proceeding or a competing representative proceeding.
5. The primary judge concluded that the speculative basis for any conclusion that new group members reasonably believed that they were group members meant that the consideration should be accorded little weight in the exercise of the discretion with respect to the amendments.
6. The applicants have not demonstrated any error in this aspect of the primary judge's reasons. It follows that contention 1(b) should be rejected.

Question 5: Did the primary judge erroneously depart from the prior decision of Moshinsky J in Impiombato No 4 at [24]-[26] (that there was a logical reason for the original description of group members having regard to the allegations concerning causation of loss) (appeal ground 4)?

1. Having decided appeal grounds 2(c) and 3 in favour of BHP Ltd, it is strictly unnecessary to determine appeal ground 4. It will therefore be addressed relatively briefly.
2. As noted above, the primary judge considered that the evidence given by Mr Watson and Mr Myers was buttressed by their statements that there was no reason why the applicants would exclude from the proceeding persons who acquired shares in BHP Ltd or BHP Plc on trading platforms or exchanges other than the ASX, LSE or JSE. In forming that view, the primary judge diverged from the view expressed by Moshinsky J on that matter. The relevant parts of the reasoning of the primary judge (Impiombato No 5 at [149]-[150]) and Moshinsky J (Impiombato No 4 at [24] and [26]) have been extracted above.
3. BHP Ltd submitted that the finding of Moshinsky J in Impiombato No 4 at [26] was part of the ratio for his Honour's decision on the scope of the group definition. It followed that the reasoning of the primary judge, which expressed a view contrary to that of Moshinsky J, failed to accord sufficient weight to the public interest in the finality of litigation and amounted to a departure from a previous ruling of the Court in conditions falling well below the "exceptional circumstances" which authority dictates are required for the Court to revisit extant orders.
4. In so far as BHP Ltd's submission is based on principles of issue estoppel, it should be rejected. For the doctrine of issue estoppel to apply, the judicial decision which is said to create the estoppel must be final: Kuligowski v Metrobus (2004) 220 CLR 363 at [21]. The observation of Moshinsky J, on which BHP Ltd relies, was not a final determination between the parties of an issue of fact. It was no more than an argument as to the likelihood of the applicants or their lawyers framing the claims in the proceeding in a particular manner. The observation was not binding on the parties and the primary judge was not bound to follow the observation.
5. In so far as BHP Ltd's submission is based on principles of finality of litigation, including in the context of interlocutory disputes, it should also be rejected. By the amendment application, the applicants were not seeking to re-agitate the application that was determined by Moshinsky J. The mere fact that, in the course of the amendment application, the applicants sought to re-agitate certain arguments that were raised before Moshinsky J (and on which they were unsuccessful) does not offend the principles of finality of litigation as discussed in the cases referred to by BHP Ltd such as Professional Administration Service Centres Pty Ltd v Commissioner of Taxation [2012] FCAFC 180; 295 ALR 52 at [53], Keynes v Rural Directions Pty Ltd (No 4) [2011] FCA 304 at [30], and Wati v Minister for Immigration and Multicultural Affairs (1997) 78 FCR 543 at 549-552.
6. For those reasons, appeal ground 4 should be rejected. The rejection of appeal ground 4 does not, however, connote acceptance of the primary judge's reasoning at [149]-[150]. What is rejected is the contention that the primary judge was legally bound to follow the observations of Moshinsky J. For the reasons expressed in the context of question 2, the primary judge's reasoning at [149]-[150] does not support a finding that the applicants and their lawyers had always intended to include as group members persons who had acquired shares in BHP Ltd and BHP Plc on trading platforms or markets other than the ASX, LSE and JSE and the lawyers had made a mistake in drafting the pleading.

Question 6: Did the primary judge place insufficient weight on the prejudice to BHP Ltd from the loss of limitation defences (appeal grounds 5 to 7)?

1. By appeal grounds 5 to 7, BHP Ltd contends that the primary judge erred by attributing little weight to the prejudice that would be suffered by BHP Ltd in back-dating the amendments to the commencement of the proceeding and thereby depriving BHP Ltd of limitation defences that would be available to it if the amendments were dated from the date they were made. The findings of the primary judge on the question of prejudice to BHP Ltd have been summarised earlier. Separate findings were made in respect of the claims of existing group members and the claims of new group members, which are considered separately below.

The claims of existing group members

1. In respect of the claims of existing group members, the primary judge concluded (at [255]) that there would be no prejudice to BHP Ltd by permitting the new claims to date from the commencement of the proceeding. That conclusion followed from his Honour's finding that the limitation periods applicable to the new claims made on behalf of existing group members were likely suspended by s 33ZE.
2. For the reasons expressed earlier, we consider that it is unnecessary to determine the dispute concerning the proper construction of s 33ZE. In resolving this appeal, we proceed on the basis that is most favourable to BHP Ltd: that the limitation periods applicable to the new claims made on behalf of existing group members were not suspended by s 33ZE, and that those claims would be time-barred but for an order of the Court relating the amendments back to the commencement of the proceeding. It follows that, for the purposes of the appeal, and contrary to the approach taken by the primary judge, we assume that there would be prejudice to BHP Ltd by permitting the new claims of existing group members to date from the commencement of the proceeding. It should also be noted that the converse logically follows from that approach: there would be prejudice to existing group members if the new claims do not relate back to the commencement of the proceeding.

The claims of new group members

1. In respect of the claims of new group members, the primary judge concluded that there would be some prejudice to BHP Ltd by permitting the claims of new group members to date from the commencement of the proceeding, because the new claims would increase BHP Ltd's potential aggregate liability in the proceeding (by removing a limitations defence). However, his Honour found that the increase in BHP Ltd's potential liability would not be material having regard to the substantial quantum of the claims already made in the proceeding (at [182] and [187]). We accept BHP Ltd's submissions that the primary judge erred in reaching that conclusion.
2. As noted by the primary judge (at [183]), evidence was given on behalf of BHP Ltd that approximately 14.5 billion shares in BHP Ltd and BHP Plc were traded on the ASX, LSE and JSE during the relevant period, and that approximately 3.3 billion shares in BHP Ltd and BHP Plc were traded on other platforms or markets during the same period. This increased the volume of share trades the subject of claims in the proceeding by approximately 22.8%. However, the primary judge concluded that the prejudice to BHP Ltd from that increase was unlikely to be material for the following reasons.
3. The first reason (at [184]) was that there was no evidence with respect to the value of the trades on the ASX, LSE and JSE on the one hand and the value of the trades on other trading platforms on the other hand. The primary judge concluded that the likely increase in potential aggregate claim value is unknown. That conclusion may be accepted as far as it goes. However, in the absence of evidence as to the likely value of trades on different trading platforms or markets, it could not be assumed that the average value of trades on the ASX, LSE and JSE was greater than or less than other platforms. In those circumstances, the increase in the volume of share trades the subject of claims was the best indication of the likely increase in BHP Ltd's potential liability. On any view, the increase is material.
4. The second reason (at [185]) was that a proportion of the trades on platforms other than the ASX, LSE and JSE would have been conducted on behalf of existing group members. Again, that conclusion may be accepted. The primary judge then concluded that, as the new claims made on behalf of existing group members were not time-barred (because of the operation of s 33ZE), they should be subtracted from the increased volume of share trades resulting from the amendments. There is no error in the primary judge's reasoning if his Honour's interpretation of s 33ZE is correct. However, as explained above, we consider that it is unnecessary to determine the dispute concerning the proper construction of s 33ZE and we proceed on the basis that is favourable to BHP Ltd: that the limitation periods applicable to the new claims made on behalf of existing group members were not suspended by s 33ZE. It follows that, for the purposes of the appeal, and contrary to the approach taken by the primary judge, we do not discount the increased volume of share trades to account for trades undertaken by existing group members.
5. The third reason (at [187]) was that the claims of existing group members are already very large. Again, that conclusion may be accepted. However, contrary to the view expressed by the primary judge, it does not follow from that starting point that a very large increase in the volume of share trades that are subject to claims (involving some 3.3 billion shares) is not a material increase in BHP Ltd's potential liability.
6. It follows that we would uphold aspects of appeal grounds 5 and 6, but we decline to determine the dispute concerning s 33ZE which is raised by ground 7.

What findings should be made about prejudice to BHP Ltd?

1. It should be accepted, as submitted by BHP Ltd, that its potential liability in the proceeding will be materially increased if the amendments have effect from the commencement of the proceeding. This is certainly the case with respect to the claims made on behalf of new group members, and we assume in favour of BHP Ltd that it is also the case with respect to the claims made on behalf of existing group members.
2. However, on the appeal, BHP Ltd did not challenge a further important finding made by the primary judge: BHP Ltd did not adduce evidence to show that, had it known of its potential increased exposure to claims, it would have taken a different approach in the litigation or to settlement (at [188]). BHP Ltd did not contend that the delay in bringing the claims that are the subject of the amendments would cause it prejudice either by reason that BHP Ltd had taken a particular approach in the litigation which it would not have taken had it faced the new claims from the outset, or by reason of the failure to investigate facts and circumstances relevant to the new claims and the inability to do so following the amendments. As already observed, the new claims sought to be advanced on behalf of both existing and new group members are based to a large extent on the same facts as already alleged against BHP Ltd concerning the collapse of the Fundão Dam and the alleged contraventions of rule 3.1 of the ASX Listing Rules and s 674(2) of the Corporations Act and the prohibitions against misleading and deceptive conduct in s 1041H(1) of the Corporations Act and s 12DA(1) of the ASIC Act. The new allegations of fact to support the new claims concern the causation of loss in respect of the acquisition of shares on trading platforms and exchanges other than the ASX, LSE and JSE. While the applicants are yet to particularise those facts and it appears that the facts will be addressed through or following expert evidence, BHP Ltd did not contend that, by reason of delay, it has been prejudiced in its ability to respond to the new claims by obtaining and adducing relevant evidence. On the findings made by the primary judge, which are not challenged on the appeal, if the amendments relate back to the commencement of the proceeding, BHP Ltd would be in no worse position in defending the claims than if the amendments had been included in the pleading from the outset.

Question 7: Did the primary judge err in taking into account the prejudice to new group members if the amendments were not permitted to relate back to the commencement of the proceeding (appeal ground 8)?

1. It is common ground that, unless the amendments relate back to the commencement of the proceeding, the claims of new group members will be time-barred by the applicable limitation provisions. The primary judge concluded that, ordinarily, that consequence is not a relevant prejudice; it is simply a consequence of the fact that the proceeding did not advance claims on behalf of the new group members (at [153]). However, his Honour considered that the position in the present case is different because the failure to advance claims on behalf of the new group members resulted from a lawyers' drafting error. In those circumstances, his Honour considered that the disadvantage to new group members is a relevant prejudice to take into account on the application (at [154]). Despite that, his Honour also reasoned that, because the new group members had never been group members, the prejudice they will suffer is not central to the decision and does not carry substantial weight (at [155] and [240]).
2. BHP Ltd's submission, that the primary judge erred in giving any weight to the prejudice that would be suffered by new group members if the amendments did not relate back to the commencement of the proceeding, should be accepted. The primary judge's reasoning was premised on his Honour's finding that the failure to advance claims on behalf of the new group members resulted from a lawyers' drafting error. Respectfully, that finding is not supported by the evidence. The proceeding never included claims in respect of the acquisition of shares on trading platforms or exchanges other than the ASX, LSE and JSE, and persons who only acquired shares in BHP Ltd and BHP Plc during the relevant period on such trading platforms or exchanges never had a reasonable basis to believe that they were group members in the proceeding. In those circumstances, their claims became time-barred by the effluxion of time, and there is no relevant prejudice in not permitting their claims to be re-enlivened.
3. It follows that appeal ground 8 should be upheld.

Question 8: Did the primary judge erroneously distinguish and thereby fail to follow the principles stated in Ethicon Sàrl v Gill (appeal ground 9)?

1. By appeal ground 9, BHP Ltd contends that the primary judge erred "in failing to follow the Full Court's binding authority on the application of s 33K … in Ethicon Sàrl". By way of particulars, BHP Ltd contends that:
2. the primary judge incorrectly distinguished Ethicon Sàrl; and
3. the primary judge ought to have applied Ethicon Sàrl such that the proposed amendments took effect from the date the amendment was permitted.
4. As BHP Ltd has demonstrated a number of errors in the primary judge's findings of fact, it is necessary for this Court to reconsider the amendment application pursuant to the power conferred by s 33K and 33ZF. In those circumstances, it is strictly unnecessary to determine appeal ground 9. Nevertheless, the ground raises important matters of principle which should be addressed, albeit briefly.
5. The contentions advanced by BHP Ltd in appeal ground 9 proceed from an erroneous understanding of the Full Court's decision in Ethicon Sàrl. The contentions are framed on the premise that the Full Court stated a binding legal rule that, on equivalent facts, is required to be followed. The Full Court did not state a binding rule. Indeed, the Full Court expressly cautioned that it would be inappropriate to lay down inflexible rules with respect to the exercise of the discretion conferred by s 33K (or 33ZF) (at [52]). The "default position" identified by the Full Court, that a s 33K order (or an equivalent order under s 33ZF) has effect from the time the definition is changed, must be understood as being in the nature of judicial guidance with respect to the exercise of the discretionary power.
6. As explained by Mason and Deane JJ in Norbis v Norbis (1986) 161 CLR 513 at 519-520, notwithstanding that Parliament may confer discretionary powers expressed in general terms, courts may develop rules or guidelines affecting the exercise of the discretion. Such rules and guidelines promote consistency in decision-making and diminish the risk of arbitrary and capricious adjudication. Generally, though, such rules and guidance fall short of constituting a binding rule. Preserving the width of the discretion which Parliament has conferred maximises the possibility of doing justice in every case, although an important countervailing consideration is consistency in judicial adjudication. Their Honours observed (at 520): The reference to "wrong principle" in the passage quoted from House v. The King no doubt refers to a binding rule rather than a guideline in the sense already explained. A failure to apply a guideline does not of itself amount to error, for it may appear that the case is one in which it is inappropriate to invoke the guideline or that, notwithstanding the failure to apply it, the decision is the product of a sound discretionary judgment. The failure to apply a legitimate guideline to a situation to which it is applicable may, however, throw a question mark over the trial judge's decision and ease the appellant's burden of showing that it is wrong. However, in the ultimate analysis and in the absence of any identifiable error of fact or positive law, the appellate court must be persuaded that the order stands outside the limits of a sound discretionary judgment before it intervenes.
7. In the same case, Wilson and Dawson JJ made the following observations about the place of judicial guidelines in the exercise of discretionary powers (at 533): … we believe that the sound development of the law, in this area as in others, is served best by following the tradition of the common law. The genius of the common law is to be found in its case-by-case approach. The decision and reasoning of one case contributes its wisdom to the accumulated wisdom of past cases. The authoritative guidance available to aid in the resolution of the next case lies in that accumulated wisdom. It does not lie in the abstract formulation of principles or guidelines designed to constrain judicial discretion within a predetermined framework. …
8. In the present case, the primary judge was not bound to follow the default position stated in Ethicon Sàrl and error is not demonstrated merely by reason of his Honour's decision not to apply the default position. Ultimately, what is required is an analysis of all of the circumstances of the case and an assessment of whether there is good reason to depart from the default position.
9. There is no doubt that the primary judge engaged in that exercise, and his Honour found that there were a number of reasons for departing from the default position in Ethicon Sàrl. The proper subject of the appeal concerns the reasons given by his Honour for departing from the default position. Respectfully, some of those reasons were based on erroneous factual findings.
10. The first reason given by the primary judge was that in this case, unlike in Ethicon Sàrl, the applicants are not seeking amendments to augment the class by introducing persons who are entirely new to the proceeding (at [217]). The primary judge reached that view because the applicants had always intended to include the new group members in the class when they commenced the proceeding but had failed to do so because of a lawyers' drafting error (see [217], [218], [219] and [220]). The lawyers' drafting error was not established on the evidence. By the amendments, the applicants are undoubtedly seeking to augment the class by introducing persons who are entirely new to the proceeding.
11. The second reason was that, if the amendments do not relate to the commencement of the proceeding, existing group members will be required to undertake factually intensive, time-consuming, and (in aggregate) costly enquiries to establish whether they are, in fact, group members, and for many such persons that will be impossible to establish (at [223]). This is an important factual finding that has not been challenged by BHP Ltd. It will be necessary to return to this matter when re-exercising the discretion.
12. The third reason was that, in ordinary inter partes litigation, the usual rule is that an amendment to correct a mistake in the name or identity of a party relates back to the commencement of the proceeding (at [225]). This consideration is also premised on the existence of a lawyers' drafting error, which was not established on the evidence. Accordingly, this consideration does not arise.
13. The fourth reason was that departure from the default position is appropriate in this case because, unless the amendments are permitted to relate back to the commencement of the proceeding, the lawyer's mistake in drafting the group definition is: (a) likely to significantly prejudice the interests of existing group members; (b) will not be in the interests of justice in the proceeding; (c) is likely to mean that the proceeding will not be conducted consistently with the overarching purpose under s 37M; and (d) gives rise to results which are antithetical to the proper operation of the regime (at [232]). To the extent this consideration is premised on the existence of a lawyers' drafting error, it does not arise. Otherwise, the reason repeats the second reason concerning the effect on existing group members.
14. The fifth reason was that permitting the amendments to relate back to the commencement of the proceeding best promotes the Court's overarching purpose under s 37M to facilitate the just determination of disputes according to law as quickly, inexpensively and efficiently as possible. This largely repeats the fourth season. The primary judge referred again to the difficulties that will be faced by existing group members in proving that they are group members, which is the subject of the second reason. His Honour also repeated that the defect in the pleading is the result of a lawyer's drafting error, which is not established.
15. The sixth reason was that his Honour was not persuaded that the increase in BHP Ltd's potential aggregate liability through the amendments will be as substantial as BHP Ltd suggests or material having regard to the very large claims already made in the proceeding (at [237]). This finding is the subject of appeal grounds 5 to 7, aspects of which have been upheld.
16. The seventh reason was that, if leave is not granted for the amendments to relate back to the commencement of the proceeding, the new group members will "suffer the disadvantage of being omitted from the class through a lawyer's error" (at [240]). This consideration is also premised on the existence of a lawyers' drafting error, which was not established on the evidence. Accordingly, this consideration does not arise.
17. Having regard to the foregoing, only two of the considerations taken into account by the primary judge in distinguishing the facts of Ethicon Sàrl are established on the evidence and have relevance. The first concerns the prejudice that would be suffered by existing group members in proving their claims if the amendments do not take effect from the commencement of the proceeding. The second concerns the prejudice that would be suffered by BHP Ltd if the amendments take effect from the commencement of the proceeding. As discussed earlier, the primary judge did not take into account the prejudice that would be suffered by existing group from the application of limitation periods if the amendments do not take effect from the commencement of the proceeding because his Honour concluded that the limitation periods had been suspended by s 33ZE. Without determining that question, we proceed on the basis that is favourable to BHP Ltd: that the new claims made on behalf of existing group members are time-barred. It follows that that additional prejudice (which cuts both ways) is also relevant.
18. In light of the foregoing, the appropriate response to appeal ground 9 is to reject it. The ground proceeds from an incorrect premise that the default position in Ethicon Sàrl is a binding rule, which it is not. Further, the primary judge did not err in his approach to the guidance provided by Ethicon Sàrl. The errors, identified above, concern findings of fact.

Reconsidering the application for leave to amend

1. As the decision of the primary judge is attended by material errors of fact, it is necessary for this Court to reconsider the question whether an order should be made that the amendments relate back to the commencement of the proceeding. The applicable principles, and the relevant findings of fact, have been discussed earlier in these reasons. Those principles and findings are relied upon without being repeated at length.
2. The starting point is the recognition that the amendments have two effects which should be separately considered. The first effect is to broaden the group definition to include persons who, prior to the amendment, were not group members. They are persons who acquired ordinary shares in BHP Ltd or BHP Plc during the relevant period only on a trading platform or exchange other than the ASX, LSE or JSE. The second effect is to broaden the claims made on behalf of existing group members to include claims in respect of the acquisition of ordinary shares in BHP Ltd or BHP Plc during the relevant period on trading platforms or exchanges other than the ASX, LSE or JSE.

Amending the group definition

1. The power to make an amendment that broadens the group definition is found in s 33K (supplemented as necessary by s 33ZE). In Ethicon Sàrl, the Full Court explained why the default position is ordinarily that such amendments take effect from the date of amendment: it "prevents the topsy turvy notion that someone retrospectively becomes a group member on commencement, when the Court has thus far proceeded on the basis that they are not group members" and avoids "the vice of potentially resuscitating causes of action by persons who have never sought to agitate them". In so far as the amendments concern the interests of new group members, being persons who acquired ordinary shares in BHP Ltd or BHP Plc during the relevant period only on a trading platform or exchange other than the ASX, LSE or JSE, save in respect of one matter, the guidance provided by the Full Court in Ethicon Sàrl is compelling. The one matter that requires further consideration arises from the difficulty faced by existing group members in proving which exchange or trading platform they acquired their shares on. This is discussed below.

Amending the claims made on behalf of existing group members

1. The power to make an amendment that broadens the claims made on behalf of existing group members is found in rr 8.21 (in respect of the originating application) and 16.53 (in respect of the statement of claim). The amendments in the present case raise claims for relief that are based on substantially the same facts as those already pleaded. Those facts concern the collapse of the Fundão Dam and the alleged contraventions of the Corporations Act and the ASIC Act by BHP Ltd. The additional facts alleged to support the new claims concern the causation of loss in respect of the acquisition of shares on trading platforms and exchanges other than the ASX, LSE and JSE. This is one of the circumstances in which the Court will often exercise its discretion, pursuant to the power conferred by s 59(2B) of the FCA Act, to order that the amendments take effect from the commencement of the proceeding, notwithstanding that the new claims would otherwise be time-barred.
2. The considerations relevant to the grant of leave to amend to add additional claims in a proceeding were considered by the High Court in Aon and have been discussed in numerous subsequent decisions. Relevant matters to consider include:
3. the nature and importance of the amendment to the party applying for it;
4. the extent of the delay and the costs associated with the amendment;
5. the explanation for any delay in applying for leave; and
6. the prejudice to the other litigants from the amendment, including as a result of decisions that had been made in the litigation prior to the application to amend.
7. In this case, the amendment is likely to be of considerable significance to existing group members. On the evidence adduced at the hearing, a very large number of acquisitions of shares in BHP Ltd and BHP Plc occurred during the relevant period on trading platforms or exchanges other than the ASX, LSE and JSE. It is reasonable to assume that a significant proportion of those transactions will have been made on behalf of existing group members. Those transactions will be brought within the scope of the claims made in the proceeding.
8. The applicants' explanation for the delay is unsatisfactory. The applicants' contention that they and their lawyers always intended to bring the claims has not been established on the evidence. Taking the evidence as it is, the explanation most favourable to the applicants is that neither they nor their lawyers turned their minds to the trading of shares in BHP Ltd and BHP Plc on trading platforms or exchanges other than the ASX, LSE or JSE. In light of the evidence given on behalf of the applicants, such as it is, it would not be open to infer that the applicants and their lawyers made a conscious decision not to pursue such claims.
9. Beyond the loss of the limitations defence, BHP Ltd has not established that it will suffer any prejudice from the grant of leave to the applicants to amend the originating application and statement of claim, with effect from the commencement of the proceeding, so that existing group members are able to advance claims for loss arising from the acquisition of ordinary shares in BHP Ltd or BHP Plc during the relevant period on trading platforms other than the ASX, LSE or JSE. BHP Ltd would be in no worse position in defending the claims than if the amendments had been included in the pleading from the outset, save for the loss of the limitations defence.
10. Having regard to the nature of the proceedings and the amendments proposed to be made, and the considerations referred to in the immediately preceding paragraphs, this is a case in which it is appropriate to grant leave to the applicants to amend, with effect from the commencement of the proceeding, so that existing group members are able to advance claims for loss arising from the acquisition of ordinary shares in BHP Ltd or BHP Plc during the relevant period on trading platforms other than the ASX, LSE or JSE.

One further issue

1. One further issue remains, which involves a difficult balancing exercise. An unchallenged finding of fact made by the primary judge is that it is likely to be very difficult, time consuming and expensive (and perhaps impossible) for persons to prove which share exchange their shares were acquired on. It follows that, if no amendment is made to the group definition which relates back to the commencement of the proceeding, it will remain necessary for existing group members to prove that they acquired at least one parcel of shares in BHP Ltd and/or BHP Plc during the relevant period on the ASX, LSE or JSE, and were thereby group members prior to the amendments being made. If a group member is unable to prove that fact (on the balance of probabilities), they will not be able to participate in any returns made to group members through the proceeding.
2. If the applicants were granted leave to amend the group definition with effect from the commencement of the proceeding, the problem of proof confronting existing group members would be largely overcome. It would not then be necessary for a group member to prove which exchange or trading platform they acquired their shares on in order to prove that they were a group member prior to the amendments. It may, however, remain necessary for a group member to prove which exchange or trading platform they acquired their shares on in so far as questions of causation of loss may differ between exchanges and trading platforms.
3. The difficult question that arises is whether this consideration, the problem of proof of group membership, is a sufficient reason not to apply the default position stated in Ethicon Sàrl and to grant leave to amend the group definition with effect from the commencement of the proceeding. On balance, it is not a sufficient reason.
4. On this issue, the interests of new group members should be given no weight. They have never been group members and their claims are time-barred. In that sense, they suffer no additional prejudice by the Court's refusal to resuscitate their claims by the device of amending the group definition.
5. The interests of existing group members will be advantaged by granting leave to amend the group definition with effect from the commencement of the proceeding. However, two matters mitigate or reduce the benefit to existing group members from amending the group definition. First, as a consequence of leave being granted to amend the claims made on behalf of existing group members (to include claims in respect of shares acquired on trading platforms and exchanges other than the ASX, LSE and JSE), existing group members will only be required to prove that they acquired one parcel of shares in BHP Ltd or BHP Plc on the ASX, LSE or JSE. A single acquisition will qualify them as group members, able to pursue claims in respect of all acquisitions during the relevant period on any exchange or trading platform. Thus, the problem of proof will be reduced. Second, even if leave is granted to amend the group definition with effect from the commencement of the proceeding, it may still be necessary for group members to prove which exchange or trading platform the shares were acquired on because the proof of causation of loss may differ between exchanges and trading platforms.
6. The interests of BHP Ltd will be prejudiced by granting leave to amend the group definition with effect from the commencement of the proceeding, principally by resuscitating claims on behalf of new group members that would otherwise have been time-barred.
7. Balancing the above considerations, we are not persuaded that the interests of justice require the grant of leave to amend the group definition with effect from the commencement of the proceeding. Indeed, it would be contrary to the interests of justice to effect a material augmentation to the group membership on a retrospective basis, imposing upon BHP Ltd a potentially very substantial increase in liability for claims that have otherwise been extinguished by the effluxion of time. The problems of proof that may be faced by existing group members are not of such a nature or scale that would outweigh the prejudice to BHP Ltd.

Conclusion

1. In conclusion, BHP Ltd's appeal against the decision in Impiombato No 5 should be allowed.
2. There is no need to vary the order made by the primary judge giving the applicants leave to file the amended consolidated originating application and the further amended consolidated statement of claim. However, the order stipulating that those documents have effect from the commencement of the proceeding should be set aside and replaced by orders that have the effect that:
3. the amendments made to the description of group members take effect on and from the date that the applicants filed their application for leave to amend, being 5 December 2023; and
4. all other amendments made to the further amended consolidated statement of claim take effect on and from the commencement of the proceeding, being 31 May 2018.
5. With respect to costs, BHP Ltd has been successful on the appeal and the result of the applicants' interlocutory application has been varied. That necessitates reconsideration of the orders of the primary judge with respect to costs and an assessment of the appropriate orders with respect to the costs of the appeal. In those circumstances, the parties should be given an opportunity to make further brief submissions with respect to the costs before the primary judge and the costs of the appeal. The question of costs can be determined on the papers. I certify that the preceding three hundred and eight (308) numbered paragraphs are a true copy of the Reasons for Judgment of the Honourable Justices Beach and O'Bryan.

Associate: Dated: 12 February 2025 REASONS FOR JUDGMENT LEE J:

A Introduction

1. I have had the advantage of reading the reasons of Beach and O'Bryan JJ (joint reasons) (whose abbreviations I will adopt) and agree with their Honours' reasons as to why the appeal from the judgment in Impiombato (No 4) must be dismissed.
2. Accordingly, I can proceed directly to the appeal from the judgment in Impiombato (No 5), which involves a contention there was error in the discretionary decision of Murphy J that amendments to the originating application and statement of claim should take effect from the commencement of the proceeding.
3. The joint reasons helpfully set out, in detail, the nature of the appeal and the arguments deployed. Although I consider that many attacks on the primary judge's careful reasons are devoid of merit, I have reached the conclusion that the orders below must be set aside. By way of explanation, I will deal initially with two preliminary points: first, about the nature of the evidentiary record below; and secondly, some observations concerning the group definition. I will then address the eight questions identified in the joint reasons (at [175] above).
4. Some issues relating the nature of a claim in Pt IVA class actions were touched upon by BHP Ltd during submissions. But Full Courts are not an occasion to engage in an early Dominican-like zeal in stamping out heresy where it is unnecessary to do so for the disposition of the appeal. Accordingly, these reasons, like the joint reasons, will not deal with all matters canvassed in submissions relating to the principled and practical operation of ss 33C, 33H, 33ZB and 33ZE of the FCA Act.

B The first preliminary matter: the evidence

1. A complication arises on this appeal by reason of how the parties dealt with the evidence below.
2. The primary judge was not assisted by the informality adopted by the parties as to the adduction and admission of evidence and a disregard of the nature of affidavits and how they come to be received into evidence. To my observation, the difficulties which can arise on appeal when such an approach is adopted seem to be occurring increasingly frequently (at least in appeals from some Registries of the Court).
3. At the risk of restating some hornbook law, it is worth noting the following.
4. What occurred below was an interlocutory hearing, and the Evidence Act applied: Evidence Act s 4(1)(b). It follows that each of the following regulated the receipt and admissibility of the evidence: Ch 2 (which deals with adduction of evidence); Ch 3 (which deals with admissibility, discretionary exclusion, and limitation of evidence and includes, by reason of s 75, an exception to the hearsay rule if the party adducing evidence adduces evidence of the source of the hearsay representation); Ch 4 (which deals with proof and includes, by reason of Div 1, requests to call witnesses); and Ch 5 (which, among other things, deals with the waiver of the rules of evidence, by order, if the parties consent (s 190)).
5. As contemplated by s 47 of the FCA Act and FC Rule 17.01, the interlocutory application was accompanied by affidavit material and evidence was proposed to be adduced by affidavit. Since one ground of appeal suggests there was no "opportunity" to cross-examine a deponent of one affidavit put before the primary judge by the moving parties, it is worth noting that in accordance with FC Rule 29.09, a party could give notice requiring a deponent for cross-examination. There was no need to ask "permission" to do so. It used to be said (and sometimes still is) that "leave" is required to cross-examine on an interlocutory application, but as I explained as part of the Full Court in Lantrak Holdings Pty Ltd v Yammine [2023] FCAFC 156 (at [28]), this line of authority, which developed in some states prior to the introduction of the Evidence Act and its cognates, is not the right starting point or frame of analysis because the Evidence Act now applies and s 27 provides that "[a] party may question any witness, except as provided by this Act" and s 29(1) provides that "[a] party may question a witness in any way the party thinks fit, except as provided by [Ch 2 of the Evidence Act] or as directed by the court". Although the Court has an express (s 11) and implied power to control the conduct of a proceeding (except so far as the Evidence Act provides otherwise expressly or by necessary intendment), given the terms of Ch 2, the question of whether cross-examination should occur on an interlocutory application is more properly framed as whether a direction should be made that it does not occur notwithstanding it is sought. When properly framed, it can be seen the mandatory considerations in s 192(2) of the Evidence Act apply to considering whether a direction ought to be made, and this cannot be reconciled with the notion that a form of "leave" needs to be sought and that such "leave" is normally granted "somewhat sparingly". Although as a practical matter the result may be the same (in that a direction there be no interlocutory cross-examination would no doubt often be appropriate when, prior to the Evidence Act, "leave" to cross-examine would have been refused).
6. As to the nature of affidavits (or more precisely the representations contained in affidavits), an important point should be stressed as noted by the Full Court in Provide Nominees Pty Ltd v Australian Securities and Investments Commission [2024] FCAFC 25; (2024) 301 FCR 569 (at 576-577 [40]-[42] per Lee J, with whom Anderson J agreed), that is that affidavits arose out of the Courts of Admiralty, Equity, Ecclesiastics and Probate in England as a departure from the rule at common law that evidence was required to be given orally in open court: see John Levingston, The Law of Affidavits (Federation Press, 2013) (at 3). One product of this feature of affidavits is that testimonial evidence led by affidavit is not adduced by merely filing the affidavit, but only by the step of reading it in open court (see Justice Alan Robertson, 'Affidavit Evidence' [2014] Federal Judicial Scholarship Articles 3). Put another way, an affidavit is "a document setting out representations by the deponent that the witness will give in the proceeding. Unless and until it is read, an affidavit usually has no broader legal effect (although the serving of it can have legal consequences, such as the waiver of privilege)". The qualification as to "usually" is where the affidavit, unusually, is received into evidence other than as testimonial evidence (see Hua Wang Bank Berhad v Federal Commissioner of Taxation (No 15) [2013] FCA 1124; (2013) 217 FCR 26 (at 29 [14] per Perram J)).
7. Bunging an affidavit into a "court book" does not constitute it being adduced into evidence. Nor is it appropriate for counsel to purport to "tender" an affidavit to be relied upon as testimonial evidence. Subject to the operation of Chapters 2 and 3 of the Evidence Act, and without being exhaustive, "real" evidence and certain certificates (see ss 177 and 178) may be tendered; an admission (contained in an answer to interrogatories or elsewhere) may be tendered, as may out of court representations contained in a document (such as a business record) or representations recorded in a transcript of a different proceeding (including a voir dire); or an agreed statement of facts. But an affidavit contains representations of a witness called in the proceeding and these representations only form part of the testimonial evidence when the affidavit is read, and the deponent thereby becomes a witness. Reading an affidavit is a necessary and critical step to its receipt as testimonial evidence, and sloppiness in this regard seems to have arisen following the passing of the time-consuming practice (common until the late 1980s, particularly in Equity, of affidavits being read out loud in court by junior counsel).
8. This is not pedantry nor the mere pointing out of solecisms. These formalities have a real purpose. Apart from emphasising that testimonial evidence is given in court by a witness, the reading of an affidavit, even if notional, provides the occasion for an objection to be taken as to admissibility (or for an application for exclusion or limitation to be made) and a ruling to follow. Following the affidavit being received into evidence after any rulings, it provides the occasion for the opposing party to challenge the evidence received by cross-examination or, alternatively, to make a forensic decision to refrain from doing so.
9. With all this in mind, we come to what happened below.
10. What occurred was suboptimal. The record does not disclose the applicants read the three affidavits of Mr Cameron Myers, a solicitor with Phi Finney McDonald, sworn 5 December 2023, 26 February 2024 and 29 February 2024, nor the affidavit of Ms Irina Lubomirska, a solicitor with Maurice Blackburn, affirmed 29 February 2024. The practice adopted below is reflected in a non sequitur recorded on the transcript by which reference was made to the last two affidavits of Mr Myers and the affidavit of Ms Lubomirska and an assertion that because "those affidavits were not objected to, so they've been read, to use the Sydney style" (T74.12-13, 25 March 2024) and a further passing reference in oral submissions to Mr Myers' first affidavit as being "the first place to start" (T21.36, 25 March 2024).
11. But even more strangely, the annexures to Mr Myers' affidavits included the following affidavits or documents (annexed material) that were on the court file being:
12. an affidavit of Mr Timothy Finney, a partner of Phi Finney McDonald, affirmed 13 July 2018;
13. an affidavit of Mr Benjamin Phi, a partner of Phi Finney McDonald, affirmed 16 October 2018;
14. an "unsworn affidavit" of Mr Jason Betts, a partner of Herbert Smith Freehills, the solicitors for BHP Ltd, dated 26 June 2020 (whatever legal status that document was supposed to have);
15. an affidavit of Ms Christine Tran, a partner of Herbert Smith Freehills, affirmed 11 December 2020; and
16. two affidavits of Mr Andrew Watson, then a partner of Maurice Blackburn Lawyers, sworn 15 October and 27 October 2023.
17. The following exchange occurred concerning one affidavit of Mr Watson (T76, 25 March 2024), which reflects the way in which the applicants (without demur from BHP Ltd) contended in submissions the annexed material was before the Court: [SENIOR COUNSEL FOR THE APPLICANTS]: And that's really undeniable on the evidence. Now, just on the solicitors - I mean, Mr Watson's affidavit is exhibited to Mr Myers' affidavit, so - at court book 430. To the extent that the solicitors' evidence is relevant as to intention - HIS HONOUR: How do I have to have regard to Mr Watson's affidavit? [SENIOR COUNSEL FOR THE APPLICANTS]: Because Mr Myers says he's informed of its - HIS HONOUR: Okay. [SENIOR COUNSEL FOR THE APPLICANTS]: It's believed to be accurate by Mr Myers, and it went into evidence as a tender, being - HIS HONOUR: Without - yes. [SENIOR COUNSEL FOR THE APPLICANTS]: - part of the exhibit to Mr Myers' affidavit. It's in evidence now. It can't be taken out of evidence.
18. If objection has been taken, annexed material was not admissible on the amendment application before the primary judge under s 75 of the Evidence Act simply because the application was interlocutory. The representations contained in the annexed material were sought to be adduced as testimonial evidence and a necessary step to their adduction into evidence did not take place. Critically, it was not proposed that the deponents became witnesses on the application. Further, I have real difficulty with the notion "the applicants sought to tender the affidavits of Mr Betts and Ms Tran, who were solicitors representing BHP Ltd, as admissions against interest". If the parties had conducted themselves in accordance with the Evidence Act, it would have been evident that the receipt of admissions is governed by Pt 3.4 of the Evidence Act. An admission that is admissible, is a previous representation made by a person being a representation that has certain characteristics. What is not admissible is the admixture of all representations made in the affidavit, most of which could not conceivably constitute an admission (such as representations which, on any view, were not adverse) except to the extent any such other representations were tendered specifically and for the purpose of providing the necessary context to understanding the admissible admission.
19. What are we to make of all of this?
20. The Full Court is a court of error. It is evident the parties proceeded below without regard to the laws of evidence and presented the case to the primary judge on the basis that all this material, including the annexed material, was somehow "in" (despite large swathes of it being plainly inadmissible).
21. The informality adopted below has some significance as ground 3 partly contends that the primary judge incorrectly weighed an absence of cross-examination where it was asserted "no relevant deponent was made available" (a matter to which I will return below).

C The second preliminary matter: the group definition

1. The first difficulty with the group definition in this class action at the time of the application was the different text employed in the originating application and the statement of claim. This led to an avoidable debate on the identity of the class. The definition should have been pellucid, given the fundamental need, in the light of the terms of Pt IVA, for group members to be ascertainable by being either named or specified by reference to criteria that makes them ascertainable.
2. I agree with the primary judge that: (a) the interpretation of the group definition should be approached objectively having regard to both the text and the context of the definition (at [22] and [25]); and (b) in the circumstances identified by his Honour, it was necessary to focus on the definition in the statement of claim.
3. In examining the second difficulty, it is necessary to set out the terms of the group definition in full: 3 The Joint Applicants and the persons they represent (the Group Members) are all persons who or which: (a) during the period from 8 August 2012 to the close of trade on 9 November 2015 inclusive (Relevant Period) entered into a contract (whether themselves or by an agent or trustee) to acquire an interest in fully paid up ordinary shares in: (i) the Respondent, formerly BHP Billiton Limited (BHP Ltd), on the Australian Securities Exchange (ASX), a financial market operated by ASX Limited (the BHP ASX Shares); (ii) BHP Group Plc, formerly BHP Billiton Plc (BHP Plc), a company registered in England and Wales, on the London Stock Exchange (LSE), a financial market operated by the London Stock Exchange Group Plc (the BHP LSE Shares); and/or (iii) BHP Plc on the Johannesburg Stock Exchange (JSE), a financial market operated by the Johannesburg Stock Exchange Limited (the BHP JSE Shares); (b) were not during any part of the Relevant Period, and are not, any of the following: (i) a director or officer or a close associate (as defined by s 9 of the Corporations Act) of BHP Ltd; (ii) a related party (as defined by s 228 of the Corporations Act) of BHP Ltd; (iii) a related body corporate (as defined by s 50 of the Corporations Act) of BHP Ltd; (iv) an associated entity (as defined by s 50AAA of the Corporations Act) of BHP Ltd; (v) a Justice, Registrar, District Registrar or Deputy District Registrar of the Federal Court of Australia or the High Court of Australia; or (vi) an officer or employee of Maurice Blackburn Lawyers or Phi Finney McDonald, or a legal representative engaged by Maurice Blackburn Lawyers or Phi Finney McDonald in this proceeding; and (c) are alleged to have suffered loss or damage by, or which resulted from, the conduct of BHP Ltd as pleaded in this statement of claim.
4. As the joint reasons note, the primary judge also made findings as to that part of the definition that provided group members are persons who, during the relevant period, "entered into a contract … to acquire an interest in … ordinary shares in … the Respondent … on the Australian Securities Exchange". His Honour considered that this should be construed as referring to ownership of shares acquired on the ASX given the word "on" qualified the acquisition. His Honour rejected an argument of the applicants that group members are persons who entered into a contract (on any platform or in any circumstances) to acquire the ownership of a particular category type of shares, being ordinary shares in BHP Ltd that were listed on the ASX. The same conclusion was reached concerning shares in BHP Plc listed on the LSE and JSE.
5. The primary judge had to do his best with an objective analysis of the definition, but it is a little difficult to see how the apparent limitation to ownership of shares is consistent with the text. The definition relates to any interest acquired by entry into a contract in an incorporeal legal right, a chose in action being, in this case, ordinary shares in BHP Ltd listed on the ASX or the LSE or the JSE. But legal or equitable interests in a chose in action arising following entry into a contract can, of course, take many forms, such as, for example, by reason of obtaining a security interest or an equitable assignment.
6. It might be thought the use of such an expansive term does not matter, but it does. There is a need for precision in group definitions. Apart from the complication of security or other interests short of legal or beneficial ownership, it appears such a broad term was employed because it was intended the group membership should include both legal and equitable owners of shares (hence the reference to the contract being entered into by a trustee). But this also gives rise to potential difficulties. A group member must have a claim against the respondent within the meaning of s 33C (not against a trustee).
7. This is not the occasion to dwell further upon these matters, but it is trite that a beneficiary under a trust has no cause of action against a third party in relation to injury to trust property unless they can establish special or exceptional circumstances and it is a duty owed by the trustee to the beneficiary to protect the trust estate or to protect the interests of the beneficiary in the trust estate. Of course, here we are dealing with statutory compensation, and further issues may arise in relation to standing to seek statutory relief. The only points to make are: (1) that if the definition is supposed to encompass purchasers who acquired ownership of shares, the definition should make that plain; and (2) the apparently widespread assumption made in class actions that trustees and beneficiaries can both always be group members does not withstand analysis.
8. The other arguments considered by the primary judge as to the group definition are summarised in the joint reasons, and it suffices for present purposes to note that the group definition was found, in effect, to extend to persons who, during the relevant period, entered into a contract to acquire ownership of fully paid-up ordinary shares in BHP Ltd through trading on the ASX and/or fully paid-up ordinary shares in BHP Plc through trading on the LSE or the JSE (at [30]). These are the persons (each with a claim that exists separately to the class action) who are already in the class action and will remain group members subject to opt out. Of course, a subset of existing group members may have additionally had purchases on platforms other than the ASX, LSE or JSE (multiple platform group member).

D.1: Did the primary judge rely on an incorrect source of power and thereby err in taking into account irrelevant considerations in the exercise of power (appeal grounds 1 and 2(a) and (b))?

1. As the joint reasons explain, BHP Ltd submitted that the primary judge erred in failing to recognise that s 33K of the FCA Act was the sole source of the Court's power to allow an amendment to the group definition in the originating application and that, as a consequence, s 33ZF of the FCA Act or FC Rule 8.21 could not be relied upon as an alternative basis to amend the group definition with retrospective effect.
2. As explained by the Full Court in Ethicon Sàrl (at 406-407 [49]-[52]), the procedural step of amending the description of group members differs from the procedural step in ordinary inter partes litigation of adding or substituting a party to a proceeding and that Pt IVA provides its own detailed regime and amendments to the description of group members are governed by s 33K, with a supplementary source of power in s 33ZF if the description is contained in a pleading. But as s 33ZG makes clear, except as otherwise provided by Pt IVA, nothing in Pt IVA affects the Court's powers under provisions other than Pt IVA. The amendments extended beyond amendments to the group definition, and the provisions of the FC Rules relating to amendment were relevant. In exercising a discretion under s 33K, authorities or principles that have been developed in inter partes proceedings do need to be approached and transposed to class actions with real caution, but it goes too far to suggest that considering them would amount to taking into account an irrelevant consideration.
3. For reasons explained in the joint reasons, although I agree that FC Rule 8.21 is not an alternative source of power to amend a group definition, this attack on the primary judge's reasons goes nowhere beyond the more substantive argument that his Honour erroneously distinguished, and thereby failed to follow, the principles stated in Ethicon Sàrl.

D.2: Did the primary judge err in finding that the applicants and their lawyers had always intended to include as group members persons who had acquired shares in BHP Ltd and BHP Plc on trading platforms or markets other than the ASX, LSE and JSE and the lawyers had made a mistake in drafting the pleading (appeal grounds 2(c) and 3)?

1. The key finding of his Honour was that the applicants and their lawyers always intended to include as group members persons who had acquired the ownership of shares in BHP Ltd and BHP Plc on trading platforms or markets other than the ASX, LSE and JSE and the lawyers had made a mistake in drafting the pleading.
2. One matter identified in the joint reasons is useful to address at the outset of this part of my reasons. Although accepting that this is an appeal against a discretionary decision to which the principles in House v The King apply, his Honour concludes that "a conclusion that the primary judge's finding was open on the evidence is not dispositive of appeal grounds 2(c) and 3". This is because the appeal is by way of rehearing in which the Court is required to determine whether the primary judge's findings of fact involved error, and no witness gave oral testimony and no witness was cross-examined: the evidence was in written form and the Full Court is in as good a position as the primary judge to make findings of fact on the evidence that was adduced at the hearing.
3. It is beyond dispute that a decision of a primary judge of the type with which we are concerned can only be overturned on appeal in five limited circumstances, being where the primary judge: (1) made an error of legal principle; (2) made a material error of fact; (3) took into account some irrelevant matter; (4) failed to take into account or gave insufficient weight to, some relevant matter; or (5) arrived at a result so unreasonable or unjust as to suggest that one or more four specific categories of error had occurred, even though the specific error did not explicitly appear on the face of the reasoning and must be inferred.
4. Here we are concerned with one form of specific error: the contention the primary judge made a material error of fact. Perhaps it is a difference in terminology, but as I understand from how the submissions of the applicants were put, it was that if the key finding was "open" to the primary judge, it was open, on the evidence adduced, to be reached without error.
5. By reference to the principles explained by the High Court in Warren v Coombes (1979) 142 CLR 531 (at 551 per Gibbs CJ, Jacobs and Murphy JJ), Allesch v Maunz [2000] HCA 40; (2000) 203 CLR 172 (at 180-181 [23] per Gaudron, McHugh, Gummow and Hayne JJ), Fox v Percy [2003] HCA 22; (2003) 214 CLR 118 (at 127 [26]-[27] per Gleeson CJ, Gummow and Kirby JJ), Robinson Helicopter Company Incorporated v McDermott [2016] HCA 22; (2016) 90 ALJR 679 (at 686-687 [43] per French CJ, Bell, Keane, Nettle and Gordon JJ) and Lee v Lee [2019] HCA 28; (2019) 266 CLR 129 (at 148-149 [55] per Bell, Gageler, Nettle and Edelman JJ), and by retaining the language of those authorities, the Queensland Court of Appeal in Wang v Hur [2024] QCA 126 (at [24] per Morrison and Bond JJA and Davis J), recently helpfully summarised the principles governing the circumstances in which an appellate court should be prepared to interfere with the fact finding made by a primary judge as follows: (a) On an appeal by way of rehearing, it is for the appellant to satisfy the appellate court that the order that is the subject of appeal is the result of some legal, factual or discretionary error. (b) On such an appeal, the appellate court is bound to conduct a 'real review' of the evidence given at first instance and of the judge's reasons for judgment to determine whether it should be so satisfied. (c) If the appellate court concludes that the judge has erred in fact, it is required to make its own findings of fact and to formulate its own reasoning based on those findings. (d) When determining whether a judge has erred in fact, in general an appellate court is in as good a position as the trial judge to decide on the proper inference to be drawn from facts which are undisputed or which, having been disputed, are established by the findings of the trial judge. (e) However, in determining whether the judge has erred in fact, an appellate court is required to exercise restraint when invited to interfere with a primary judge's findings of fact, at least where those findings are likely to have been affected by impressions about the credibility and reliability of witnesses formed by the trial judge as a result of seeing and hearing them give their evidence. Such appellate restraint applies not merely to findings of primary facts but also applies to findings of secondary facts which are based on a combination of these impressions and other inferences from primary facts. (f) In such cases, a finding of fact is not to be set aside because an appellate court thinks that the probabilities of the case are against - even strongly against - that finding of fact. The finding must stand unless it can be shown that the trial judge 'has failed to use or has palpably misused [his or her] advantage' or has acted on evidence which was 'inconsistent with facts incontrovertibly established by the evidence', or which was 'glaringly improbable', or which was 'contrary to compelling inferences'."
6. Consistently with these principles, it is not for an appellate court simply to reach a different conclusion because it considers it subjectively appropriate to do so. Mere disagreement does not equate with error even if the relevant finding was based upon documentary material and not dependent upon, or affected by, impressions about the credibility and reliability of witnesses. After all, some findings of fact, made on the balance of probabilities, are based upon evidence aspects of which can sometimes point in different directions (and over which different tribunals of fact, acting rationally, can reach a different conclusion without recognisable error).
7. The following two points can be made about the evidence before coming to the unchallenged affidavit material.
8. First, it is correct to say that the pleadings, both before and after consolidation, are focussed on the trading of ordinary shares in BHP Ltd on the ASX and the trading of ordinary shares in BHP Plc on the LSE and JSE, and no allegations concerning the causation of loss in respect of an acquisition of shares in BHP Ltd or BHP Plc being acquired on any exchange, or in any manner, other than by trading on the ASX, LSE or JSE.
9. Secondly, it is also correct that the pleadings do not reflect an intention by the applicant to advance a claim in respect of shares in BHP Ltd and BHP Plc acquired otherwise than on the ASX, LSE or JSE.
10. Read fairly, it is evident that the approach taken by the primary judge was to consider whether these objectively verifiable facts were explained in the way the applicants contend they can be explained. The relevant question on appeal is whether we consider the primary judge erred by failing to conclude that the evidence, taken as whole, was unsatisfactory and had insufficient probative value.
11. The evidence treated as being before the primary judge has been thoroughly and helpfully set out in the joint reasons. I will not repeat that analysis or set out the roles of various "witnesses", and it is only necessary for me to refer to the highwater mark of the representations contained in the affidavit material.
12. The first is that of Mr Watson (15 October 2023 (at [18])) as follows: At all times since the commencement of this proceeding, the Applicants' intention was, and remains, to bring a proceeding on behalf of all persons who acquired an interest in shares in the Respondent or BHP Plc during the Relevant Period. On the Applicants' case, all such persons would have suffered loss or damage by, or as a result of, the Respondent's conduct alleged in the ACSOC. There was and is no reason why the Applicants would exclude from the proceeding persons who acquired shares in the Respondent or BHP Plc through platforms other than the ASX, LSE or JSE. It is my view that the description of the group members in the COA and ACSOC reflects that intention. At all times, the Applicants have conducted the proceeding on the basis that the group members included all persons who had acquired an interest in shares in the Respondent and BHP Plc during the Relevant Period.
13. To similar effect was the evidence of Mr Myers (5 December 2023 (at [23], [25], [27], [42], [53]); 29 February 2024 (at [7]-[8])) that: When commencing this Proceeding and the Klemweb Proceeding, the Applicants' intention was, and remains, to bring proceedings on behalf of all persons who acquired an interest in shares in BHP Ltd and/or BHP Plc during the Relevant Period, irrespective of the market or platform or means of trade through which those trades occurred.

Furthermore, at all times since commencing the proceedings, the Applicants have conducted them on the basis that the group members included all persons who had acquired an interest in fully paid up ordinary shares in BHP Ltd and/or BHP Plc during the Relevant Period. …

I understood when the Proceeding was commenced, and at all times since, that the references to the ASX, LSE and JSE in the context of the descriptions of the group members and other parts of the pleadings reflected the dual-listed structure of BHP Ltd and BHP Plc, and referred to shares on the ASX, LSE and JSE in the sense of being listed or quoted on those exchanges. I did not understand the references to the ASX, LSE and JSE to introduce any limitation on, or criterion for, group membership such that a person's acquisition of shares in BHP Ltd or BHP Plc had to occur through trading on those exchanges.

I believe, based on information from Ms Lubomirska and Ronald Koo, now a Principal of MB, that at all times since prior to the commencement of the Klemweb Proceeding, and following consolidation, MB intended to bring the proceedings on behalf of all persons who acquired shares in BHP Ltd and/or BHP Plc during the Relevant Period, irrespective of the platform or other means of trading through which those shares were acquired. I further believe, based on information from Ms Lubomirska and Mr Koo, that at all times they understood that the references to the ASX, LSE and JSE in the context of the descriptions of the group members reflected the dual-listed structure of BHP Ltd and BHP Plc, and not that group membership was restricted to persons who acquired shares on those specific exchanges.

To the extent that the Applicants failed to execute their intention… to include all persons who acquired shares in BHP Ltd and BHP Plc in the description of the group members in the originating applications and pleadings filed in the proceedings, that was an inadvertent mistake in the drafting, which the Applicants now seek to correct by their amendment application.

I am informed by Mr Impiombato, that it was his intention to bring proceedings on behalf of a group comprising all people who bought shares in BHP Ltd and/or BHP Plc (BHP).

1. Further, Ms Lubomirska made similar representations as to what was conveyed to her by Mr David Webb (a director of Klemweb) as to communications that occurred between Mr Webb and another solicitor, Ms Dellavedova, prior to the commencement of the Klemweb proceeding in 2018.
2. Several things can be observed about this material.
3. First, I have already explained the heterodox way the representations of Mr Watson were placed before the primary judge. But given we must proceed on the basis the material was "in", I disagree that the practical consequence of the applicants' decision to place the representations before the Court in the way that they did was that "the evidence contained in those affidavits was not able to be tested by cross-examination".
4. Rather, the real practical consequence of the parties proceeding the way they did was that the representations of Mr Watson, which were inadmissible, were placed before the primary judge. As the primary judge correctly concluded, the decision to allow this material to be placed before the Court without challenge was a forensic choice made by BHP Ltd (which was explained by BHP Ltd as reflecting an assessment as to the infirm nature of this and the other testimonial evidence).
5. Secondly, although all these representations, none of which were the subject of objection or limitation pursuant to s 136 of the Evidence Act, do not directly address the question as to whether the applicants were aware at the time of drafting that shares in BHP Ltd and BHP Plc could be acquired on trading platforms or exchanges other than the ASX, LSE or JSE, or in off-market transactions, they do convey unqualified statements as to the subjective view taken by the applicants as to the terms of the group definition (although that view has been demonstrated to be objectively wrong).
6. Thirdly, obviously enough, the adduction of hearsay evidence of a representation in an interlocutory application can sometimes occasion unfairness. Leaving aside form issues, any such unfairness arising from the receipt of even admissible hearsay on an interlocutory application, can, of course, be remedied, in an appropriate case, in at least three ways: (1) by discretionary exclusion under Pt 3.11 of the Evidence Act on the basis, for example, that the probative value of the relevant representation is substantially outweighed by the danger that the evidence might be unfairly prejudicial to the respondent (see s 135(a)); (2) by discretionary limitation under Pt 3.11 of the Evidence Act if there is a danger the representation would be unfairly used to prove the truth of the disputed out of court representation (see s 136(a)); or (3) by making a reasonable request under Pt 4.6 of the Evidence Act for the purpose of determining a question that relates to a representation by requesting the claimant to call as a witness the person who made the representation (see s 166(f)).
7. Of course, in this case, no form objections were made; no applications were made for discretionary exclusion nor limitation; and no request to call the maker of a previous representation was made. As noted above, this was a forensic choice of BHP Ltd.

D.3: Did the primary judge err in failing to find that the applicants had conducted the proceeding on the basis that the group members included all persons who acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period, irrespective of the market, trading platform or means of trade through which they acquired that interest (contention 1(a))?

1. As the joint reasons note, this contention was not at the forefront of the argument of the appeal. This is understandable as group membership must be determined objectively and the fact the applicants continued to labour under a misapprehension as to whether all persons who acquired shares in BHP Ltd and BHP Plc during the relevant period were group members is not to the point. It adds nothing to the initial mistake made by the applicants.

D.4: Did the primary judge err in failing to find that persons who acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period on a trading platform or market other than the ASX, LSE or JSE (new group members) had reasonable grounds to believe that they were group members (contention 1(b))?

1. A similar point can be made as to the assertion that the primary judge erred in failing to find that persons who only acquired an interest in shares in BHP Ltd and BHP Plc during the relevant period on a trading platform or market other than the ASX, LSE or JSE (that is, proposed new group members) had reasonable grounds to believe that they were always group members. This fact may have some relevance in other contexts (such as on an application under s 1322(4)(d) of the Corporations Act to extend the time in which a claimant could bring a case or in assessing prejudice to third parties), but is not relevant to the objective characterisation of who is a group member. In any event, there is no error evident in the primary judge's conclusion in this regard.

D.5: Did the primary judge erroneously depart from the prior decision of Moshinsky J in Impiombato (No 4) (at [24]-[26]) (that there was a logical reason for the original description of group members having regard to the allegations concerning causation of loss) (appeal ground 4)?

1. I agree it is unnecessary to determine appeal ground 4.

D.6: Did the primary judge place insufficient weight on the prejudice to BHP Ltd from the loss of limitation defences (appeal grounds 5 to 7)?

1. To my mind, the heart of this appeal is the contention that the primary judge erred by attributing little weight to the prejudice that would be suffered by BHP Ltd in back-dating the amendments to the commencement of the proceeding, thereby depriving BHP Ltd of limitation defences.
2. His Honour (at [93]) accepted that expanding the class would increase BHP Ltd's potential aggregate liability in the proceeding occasioning prejudice. However, the primary judge found (at [182] and [189]) that this prejudice was "unlikely to be material in the context of the case".
3. His Honour referred (at [183]) to the evidence that a total of approximately 14.5 billion BHP shares were traded on the ASX, LSE and JSE during the relevant period and that approximately 3.3 billion BHP shares were traded on secondary platforms during the same period. His Honour correctly dismissed as simplistic the contention of BHP Ltd that this involved an "approximately 22.8% increase in the size of the class (3.3 billion of 14.5 billion acquisitions)". The primary judge recognised that this analysis was flawed (even leaving aside the position of existing group members who were a multiple platform group member) given any increase in aggregate value of the group member claims was imprecise.
4. It is the next step, however, that I consider to be problematical. With great respect to the careful and learned reasons of his Honour, for the reasons that follow, I do not think it was open to find (at [189]) that the prejudice "was unlikely to be material in the context of the case" and, as a consequence, error has thereby been established.
5. It is common ground that the limitation periods applicable to the claims advanced in the class action are six years: see ss 1041I(2), 1317K and 1325(4) of the Corporations Act.
6. Although there are textual differences between these provisions, they can all be seen, at least generally, as reflecting and representing the Parliament's intention and judgment that the welfare of society is best served by these statutory causes of action, allowing for an award of compensation being litigated within a limited time of six years, notwithstanding that the enforcement of these time periods may result in good causes of action being defeated: see, more generally, Brisbane South Regional Health Authority v Taylor (1996) 186 CLR 541 (at 553 per McHugh J).
7. It has long been thought that such limitation periods are justified by, inter alia, a recognition that as time goes by relevant evidence is likely to be lost; it is oppressive to a respondent to allow an action to be brought long after the circumstances that gave rise to it occurred; it is desirable for people to be able to arrange their affairs and utilise their resources on the basis that claims can no longer be made against them after a certain time; and, importantly, the public interest requires that disputes be settled as quickly as possible: Brisbane South Regional Health Authority (at 553 per McHugh J).
8. This is not a case where a plaintiff in actual or proposed inter partes litigation is seeking an extension in relation to relief arising from a justiciable controversy between the plaintiff and a defendant. By way of contrast, here we are partly dealing with non-parties; strangers to the class action, who have taken no steps to agitate any relevant claim they have or may have had. By operation of law, any controversy between the proposed new group member and BHP Ltd, which upon amendment is now said to give rise to an entitlement to statutory compensation, has either not arisen or has already been quelled by operation of law, given the effluxion of six years.
9. Irrespective of the fact that BHP Ltd is facing the substantial claims of existing group members, there is no extant issue between BHP Ltd and the third party strangers affected by the proposed amendment, and BHP Ltd, absent any amendment, is entitled to act and organise its affairs on the basis that no controversy exists between it and those third parties. Resuscitating a controversy in these circumstances does amount to material prejudice.
10. For completeness, even though no evidence was adduced that any third party (that is, a proposed new group member) did wish to seek relief, this prejudice exists irrespective as to whether one of the third parties did now belatedly decide that they wished to seek relief. It was not in dispute below that different judicial views have been expressed as to when s 1322(4) of the Corporations Act may be invoked to extend limitations periods, including, most recently, in Binqld Finances Pty Ltd (in liq) v Binetter [2024] FCA 361. In Binqld, Kennett J considered the potential use of s 1322(4)(d) to extend the limitation period prescribed in s 1317K for bringing an application for a compensation under s 1317H and concluded that an earlier decision, Austructures Pty Ltd v Makin [2014] VSC 544; (2014) 103 ACSR 307, ought to be followed. In Austructures, Almond J had held, in the context of an amendment application, that the general remedial provision cannot operate to extend the time limit prescribed in s 1317K. No consideration was given in the judgment below (or argument presented on this appeal) as to the correctness of this line of authority or whether it can be distinguished in the context of the other differently worded limitation periods presently applicable (ss 1041I(2) and 1325(4)); nor was error alleged in the conclusion of the primary judge that it was unnecessary to decide, for the purposes of this application, the availability or otherwise of an order under s 1322(4) if the amendment for the proposed new group members did not "relate back". The possibility or otherwise of an entitlement of a third party to make an application to extend any applicable period does not detract from the existence of a material prejudice in resurrecting expired claims more generally.

D.7: Did the primary judge err in taking into account the prejudice to new group members if the amendments were not permitted to relate back to the commencement of the proceeding (appeal ground 8)?

1. By reason of the fact that the failure to advance claims on behalf of the proposed new group members resulted from a drafting error, the primary judge considered (at [154]) that the disadvantage to proposed new group members is a relevant prejudice to consider on the application.
2. The difficulty with taking into account this consideration is that there was no evidence adduced that any third party wished to agitate any claim. One would ordinarily think a relevant prejudice arises because a proposed outcome prevents a person enjoying a benefit or right the person otherwise wished to enjoy or exercise. At present, the claims are time-barred by the effluxion of time, and no one has indicated any intention to seek any extension (even if it was available). It is difficult to see how a relevant and real prejudice to these third parties does exist on the evidence before the primary judge. Notably, the prejudice was not expressed by being a prejudice to another third party, being the litigation funder, whose commercial interests are no doubt affected by any failure to augment the value of the collective claims in the class action by augmentation of the class.
3. However, error has otherwise been established and a fair reading of the judgment does not demonstrate that any finding in this regard was material to the exercise of his Honour's discretion. Hence it is unnecessary to reach a conclusion as to whether appeal ground 8 should be upheld.

D.8: Did the primary judge erroneously distinguish and thereby fail to follow the principles stated in Ethicon Sàrl (appeal ground 9)?

1. I agree with the joint reasons as to why there is no substance in this ground. The primary judge plainly understood the "default" position as explained by the Full Court in Ethicon Sàrl and did not err in his approach to the guidance provided by that decision.

E Re-exercise of discretion

1. It follows that I have come to the same conclusion as the joint reasons that the discretion must be re-exercised.
2. I proceed on the basis that there was no error in the primary judge's finding of fact that the applicants did not intend to exclude any group of persons who acquired BHP shares and those responsible for the drafting did not turn their minds to the trading of shares in BHP Ltd and BHP Plc on trading platforms or exchanges other than the ASX, LSE or JSE. In this way, as the primary judge found (at [151]), the "operative mistake" was inadvertently framing the group definition in a way which was inconsistent with the applicants' intention, and the intention of the pleader.
3. In the light of this, and although the discretion must be exercised by reference to all relevant matters, the following factors are of significance.
4. First, as to the finding of fact made by the primary judge that it is likely to be difficult for persons to prove the share exchange upon which their shares were acquired, any notion this causes some problem relevant to amendment for existing group members (including the multiple platform group members) is unpersuasive. Each group member will need to prove they suffered loss upon a purchase of BHP shares, irrespective as to the registry upon which the share was acquired. Whether there is a difference in the approach to causation or loss depending upon the relevant registry will either be a matter to be determined at the initial trial (to the extent it is relevant to any issue of commonality determined at that initial trial) or later when it comes to assessing an individual claim of a multiple platform group member. How a multiple platform group member proves their loss is a matter for trial.
5. If the applicants were granted leave to amend the group definition with effect from the commencement of the proceeding, it puts it too highly to suggest that this will overcome any alleged difficulties of proof. Determining the identity of the registry will either be relevant to proving causation or loss or it will not be. We have insufficient information to know whether that will be the case at all, or at the initial trial, or later when it comes to individual assessment. This is just a matter inherent in the nature of the claim. Focussing only upon class composition, if an amendment was allowed to relate back, the proposed new group members, who only purchased on an exchange other than the ASX, LSE or JSE, will need to prove they are a member of the class, but that is again just a consequence of the nature of the claim.
6. Secondly, although I accept a drafting mistake was made, in the absence of a third party or parties suggesting that they wish to agitate a claim against BHP Ltd or any evidence that they thought their limitation period had been tolled (and hence refrained from taking steps to protect their position), I do not place significant weight on the alleged prejudice to any proposed new group members caused by the drafting mistake. No doubt it is in the commercial interests of the promoters of the class action to increase the class and hence quantum, but that is not how the prejudice was put. We must deal with the evidence as it is, and we are not dealing with an application by a person or a group of persons to extend the period for bringing a claim who contend they have suffered prejudice (to the extent such an application is able to be brought).
7. Thirdly, for the reasons I have explained, the interests of BHP Ltd will be materially prejudiced by granting leave to amend the group definition with effect from the commencement of the proceeding by bringing in claims of new group members.
8. Finally, again accepting a drafting mistake was made, the principles regarding amendments to correct a mistake in the name or identity of a party have little present relevance. We are in a different realm of discourse than a case where a claim was made against AB Ltd when the intention was always to make it against ABC Ltd. I respectfully disagree that orders granting leave to correct a lawyer's mistake in the name or identity of a party have any relevant similarity with the bespoke task of changing group membership. In this regard, it is worth repeating (and emphasising an important part) of what the Full Court said in Ethicon Sàrl (at 406-407 [49]-[52]): [49] The second difficulty is more significant and relates to the inaptness, or at least the limitations of, drawing analogies between aspects of ordinary inter partes litigation and Part IVA procedures. Although s 33ZG provides that nothing in Part IVA affects the Court's powers under other provisions, Part IVA provides its own bespoke and detailed regime and, in significant respects, the evident purpose of the Part is to displace generally understood procedures: see Wong v Silkfield Pty Ltd [1999] HCA 48; 199 CLR 255 at 260-261 [11] (Gleeson CJ, McHugh, Gummow, Kirby and Callinan JJ). [50] By the amendment of a group definition, a new group member affected is not becoming a party, still less is the group member an existing party seeking to bring a new cause of action arising out of similar circumstances. The legal consequence is that the claim of a new group member, which claim gives rise to at least one substantial issue of law or fact with others, has become subject to the operation of the Part, subject to opt out or declassing. When one recognises that the regime expressly contemplates and provides for the individuality of claims within a group proceeding, what is brought into focus is that an order for amendment, which has the consequence of expanding the group definition, is sui generis and that analogies drawn from other contexts are apt to mislead. [51] It is consistent with the scheme introduced by Part IVA and, in particular, the need for there to be certainty as to the persons who comprise the class at all times, that the Group Definition Amendment should have been ordered to take effect from the date of amendment, being the date of filing of the 5FASOC. To adopt that course is consistent with the expansion of the class effected by the earlier Amendment Orders which, unfortunately, were not drawn to the attention of the primary judge in the present context. Apart from anything else, this prevents the topsy turvy notion that someone retrospectively becomes a group member on commencement, when the Court has thus far proceeded on the basis that they are not group members. As a matter of principle, such an approach would avoid the vice of potentially resuscitating causes of action by persons who have never sought to agitate them. It would be odd that by becoming a group member through the augmentation of a class, substantive rights were conferred on a claimant that had been either extinguished or barred by operation of statute and could not otherwise be advanced by that claimant. [52] Before leaving this topic it is worth making a further point. Given the suspension of limitations caused by the operation of s 33ZE, the question of inclusion (or, as occurred here, unusually, exclusion) of group members has potentially important consequences on substantive rights. As does the date when any such order is to take effect. Whatever might be the nature of other amendments to a statement of claim, or to relief claimed in an application, attention must be given by parties to the legal consequences of class composition changes. Irrespective as to when other amendments might take effect, the consequences of amendments to group definition can affect the rights of third parties, being the absent group members or proposed group members. Although it would be inappropriate to lay down inflexible rules, the default position is that a s 33K order (or an equivalent order under s 33ZF) has effect from the time the definition is changed, consistent with the requirements of class certainty. It is a sound practice for applicants, in seeking such orders, to deal separately with amendments concerning class composition to assist in avoiding any confusion. (Emphasis added)
9. The observations resonate with force in the present circumstances. Notwithstanding the mistake made, I agree it would be contrary to the interests of justice to change the group membership to include belatedly persons whose claims cannot now be brought because of the effluxion of time. Hence, I agree there is a need to vary the orders of the primary judge.
10. The orders referred to in the joint reasons are to be made. For my part, I would have stood the matter over to allow any necessary amendments to give effect to the new pleading and, importantly, to address the issues of ambiguity and uncertainty in class composition to which I referred in Section C of these reasons. Further, I do not consider it necessary to make a "relate back" order to allow the whole of the s 33C claim of those group members who are multiple platform group members (and whose claims were within a class action commenced within time) to be advanced when appropriate (either at some stage during the currency of the class action or following any declassing). I certify that the preceding eighty-five (85) numbered paragraphs are a true copy of the Reasons for Judgment of the Honourable Justice Lee.