Plaintiff v First Defendant

1 This group proceeding, issued under Part 4A of the Supreme Court Act 1986 (Vic), concerns the alleged presence of so‑called 'defeat devices' in Mercedes‑Benz branded diesel fuelled motor vehicles sold and acquired in Australia during a 17 year period. Defeat devices are mechanisms prohibited by rules made under the Road Vehicle Standards Act 2018 (Cth). They allow vehicles to pass the emissions tests necessary to meet Australian road vehicle standards while at the same time allowing the vehicles to emit higher levels of pollutants under normal driving conditions. The plaintiff's case is that Mercedez‑Benz represented that its vehicles met the relevant standards but in fact that was not the case because they contained defeat devices. Among other things the plaintiff claims loss arising from non‑compliance with guarantees under the Australian Consumer Law.

2 The plaintiff has sought leave[1] to amend the statement of claim, including by amending the definition of the persons represented by the plaintiff (group definition). The document in issue is dated 14 November 2024 (Amended Statement of Claim or ASOC[2]), which the plaintiff filed purportedly relying on Order 36 of the Supreme Court (General Civil Procedure) Rules 2015 (Vic) (Rules), to amend without leave prior to the close of pleadings. The plaintiff belatedly accepted that leave under s 33K(1) of the Supreme Court Act was required to amend the group definition and seeks leave to amend paragraph 1 of the pleading, nunc pro tunc. The defendants say that leave should be refused and instead seek orders[3] that:

1. The amendment of the group definition in paragraph 1 of the ASOC be disallowed under r 36.04(2) of the Supreme Court (General Civil Procedure) rules 2015 (Vic) (Rules).

2. The ASOC be struck out pursuant to r 23.02 of the Rules.

1. Alternatively to order 2, paragraph 1 of the ASOC be struck out pursuant to r 23.02.
2. Further to order 3, and alternatively to order 2, paragraphs 25 to 25B of the ASOC be struck out pursuant to r 23.02 of the Rules.
3. Alternatively to order 4, further and better particular of paragraphs 25 to 25B of the ASOC be provided to pursuant to r 13.11 of the Rules.
4. Costs.

(a) leave to amend sub‑paragraphs 1(a)(i) and 1(b) of the ASOC is granted;

(b) sub‑paragraph 1(a)(ii) of the ASOC is struck out;

(c) paragraph 25B of the ASOC is struck out;

(d) the plaintiff have leave to replead those parts of the claim that are struck out pursuant to orders (b) and (c) and to make any necessary consequential amendments.

4 Paragraph 1 of the ASOC reads as follows (with changes marked up from the plaintiff's original pleading):

The plaintiff commences this proceeding in a representative capacity pursuant to Part 4A of the Supreme Court Act 1986 on her own behalf and on behalf of all persons who:

(a) between 1 January 2008 and the date of commencement of these proceedings ('Relevant Period') acquired from the First Defendant or one of its retailers or dealers in Australia, an equitable or legal interest (including under a hire‑purchase agreement, but extending a mere leasehold interest) in a Mercedes‑Benz diesel vehicle:

(i) in the same kind of vehicle of the same engine type as the Applicant's Plaintiff's Second Vehicle (as defined in paragraph 3(b) below), as set out in Annexure A to this Statement of Claim, or

(ii) any other Mercedes‑Benz vehicle sold by the First Defendant or one of its retailers or dealers in Australia containing which contained, from the time of supply, the same or similarly operating Defeat Devices (as that term is defined in paragraph 23 below) as one or more of the Mercedes Defeat Devices pleaded as defined in paragraph 25 below,

(b) at any time during the Relevant Period acquired in Australia title to an Affected Vehicle from, through or under a person who acquired the vehicle in the circumstances referred to in sub‑paragraph (a) above,

but not including the Defendants, or anyone who is, or has been at any time since 1 January 2008:

(c) a wholly or partly owned subsidiary of any of the Defendants;

(d) any authorised dealer of any of the Defendants; or

(e) any person described in s 33E(2) of the SCA,; or

(f) the Plaintiff's legal representatives,

('Group Members', which includes the Plaintiff).

5 The group definition which appears in paragraph 1[4] of the ASOC contains two limbs.

6 The defendants did not press any objection to the first limb, contained in sub‑paragraph 1(a)(i). The first limb of the group definition was clumsily expressed and apt to confuse by referring to vehicles of 'the same engine type of the plaintiff's second vehicle' (as described in a different part of the pleading) and also to Annexure A. The Annexure set out a list of Mercedes‑Benz models described by year, body type and engine type. The issue was one of expression rather than substance. Counsel accepted the criticism and agreed that it could and should be amended in the way described below. The plaintiff's Senior Counsel said that that part of the definition need only refer to vehicles meeting the description set out in Annexure A. If that limb of the definition is amended in substance in that way, the ambiguity which it presently contains will be removed.

7 The amendment to sub‑paragraph 1(a)(i) includes the addition of the words, 'from the First Defendant or one of its retailers or dealers in Australia' and 'in a Mercedes‑Benz diesel vehicle.' I am satisfied the original definition made reference to the sale of vehicles in Australia, but in a way that was less than clear. The amendment is one of form, not substance.

8 The reference to diesel vehicles is new. The plaintiff contends that construing the original definition in the context of the statement of claim, it is apparent that the claim was always limited to diesel vehicles. On balance, I do not agree. The original claim referred to diesel vehicles in paragraph 2 and the represented class was defined in part by reference to vehicles of the same kind as the plaintiff' second vehicle which was a diesel vehicle. However, the class was also defined to include those person who purchased 'any other Mercedes‑Benz vehicle sold by the First Defendant or one of its retailers in Australia containing the same or similarly operating defeat devices'. Objectively construed,[5] the claim did not indicate that such vehicles were limited to diesel vehicles. The effect of that aspect of the amendment is to narrow the represented class. That will mean that group members originally included but now excluded from the claim will be returned to the position they were in before the commencement of the proceeding. In the circumstances I conclude that the amendment is not unfair or unreasonable in the sense of being adverse to group members' interests,[6] for these reasons:

(a) I accept the plaintiff's evidence (given by its solicitor) that it was not subjectively intended to advance a claim in respect of petrol‑fuelled vehicles, that the plaintiff has not investigated and has not identified a reasonable basis for such claims. The plaintiff's solicitors do not consider on the material available to them, that they have a basis to allege the existence of defeat devices in petrol‑fuelled Mercedes‑Benz vehicles. I do not consider that it is adverse to affected group members' interests to allow the amendment and thereby avoid a situation where the plaintiff is effectively forced to prosecute a case in respect of which the plaintiff's solicitors have not established to their own satisfaction, a reasonable basis.

(b) All of the communications to potential group members from the plaintiff's solicitors (including the plaintiff's summary statement filed pursuant to the Court's practice note) refer expressly and only to Mercedez‑Benz diesel vehicles. No court‑ordered notices to group members have yet been issued. Notices issued under s 33Y will make the position clear.

10 The time at which the amendment should take effect will be determined upon hearing from the parties. On this application the parties made limited submissions on that question, not specifically directed to this aspect of the definition.

11 In relation to the second limb, the plaintiff did not have leave, pursuant to s 33K, to make the amendment that appeared in ASOC [(1)(a)(ii)], and sought leave nunc pro tunc. I would refuse that leave, but observe that the original form of that sub‑paragraph has the same problems as the proposed amendment. Accordingly, the appropriate order is to strike out that sub‑paragraph.

12 The defendants' submissions were directed to the group definition and to paragraphs 25A to 25B of the ASOC. The application in respect of the whole of the statement of claim appears to be predicated on the possibility that the whole of paragraph 1 might be struck out, leaving the proceeding without a defined group.

(a) To be properly constituted the matters specified in s 33H(2) must be pleaded such that there is certainty of group composition from the commencement of the proceedings and throughout the currency of the proceeding. Compliance with s 33H cannot be overlooked or deferred as a matter of discretion, until a later stage in the proceedings (say, until after discovery). The plaintiff's proposal that the group definition be clarified after discovery is inconsistent with principle and should be rejected. Nor can the requirement to comply with s 33H be ameliorated in reliance on discretionary considerations.

(b) In order to comply with s 33H(2)(a) the group definition must be sufficiently clear and precise so that group members can reasonably ascertain whether they are captured, by reading the definition and relevant parts of the pleading. In this case the group definition does not comply with 33H(2)(a) because it is convoluted, technical and ambiguous, such that no potential group members could determine whether they fall within the group definition, even with legal assistance. It is not seriously disputed that because the group definition incorporates the 'defeat device' allegations, group members could not in any practical sense, determine whether they are group members.

(c) In addition, the group definition ought not be premised on a central matter in dispute (the presence of defeat devices in affected vehicles).

(d) More generally the 'defeat device' pleas are embarrassing because they are general and unclear and do not plead all material facts. The lack of clarity is important because those allegations are the foundation for all of the allegations of breach of legal obligation, including allegations that the defendants knew that each affected vehicle contained a defeat device and did not conform with the relevant laws, but did not inform the Federal Government of that fact, and that the defendants engaged in unconscionable conduct on the basis that (among other things) they programmed the affected vehicles to contain the defeat devices.

(a) The group definition conforms with s 33H. While making reference to a technical matter that concerns concealed parts of motor vehicles, it is sufficiently clear. It is not in contest that the proceedings have been properly constituted under s 33C.

(b) There is nothing in the language of s 33H that requires group members to know that they are group members, by reference to the definition, at least not at an early stage of proceedings. The primary purpose of s 33H is to allow the Court to determine whether the threshold requirements stipulated in s 33C have been met. Permitting potential group members to determine whether they fall within the class is a secondary purpose. It is not necessary that the group definition serve the secondary purpose, conformably with s 33H. The words of the section to not impose that requirement. The ability of a person to determine whether they are a class member, if necessary, can be considered at a later stage, after discovery. That 'stage' must be reached before the Court issues any judgment in a proceeding: s 33ZB.

(c) As a matter of practicality, in this case, the stage has not yet been reached where it is necessary or indeed possible, for the plaintiff to describe with any greater precision, the group members that the second limb of the group definition is intended to capture (the 'unspecified engine group members'). The only substantive step that has occurred is the filing of the pleadings. The need to issue notices has not yet arisen. Notices need only be given under s 33X(6) as soon practicable after the happening of an event to which the notice relates. An assessment of practicality will be informed by the Court's case management powers. Notices are not typically given personally and could be given to all members of the broadest possible class, for example, all buyers of Mercedez‑Benz vehicles within the relevant period, without positively identifying its constituents.

(d) The defendants hold the information required to respond to the pleadings. To directly identify a defeat device either requires expensive vehicle testing or a person to access and interpret the proprietary computer code of a vehicle's engine control unit, which is code in the hands of Mercedes. The plaintiff proposes to clarify the identity of group members following discovery from Mercedes.

(e) If the Court were to strike out or disallow the second limb of the group definition, current group members who fall within that limb, would be excluded from the proceeding and in order for them to pursue claims against the defendants it would be necessary for them to make application for preliminary discovery, seeking documents that disclose the identity of other vehicles (beyond those described in Annexure A to the ASOC) that contain a defeat device. Those applications are expected to be numerous because there may be as many as 22 types of Mercedes‑Benz vehicle engines. It would not be conducive to the overarching purpose to allow the resources of the Court and the parties to be consumed dealing with applications of that kind, which would ultimately lead to the same result that would flow from the making of discovery order in these proceedings. The Court should allow the amendments on the basis that the plaintiff will at an appropriate time seek orders for discovery necessary to articulate the case with greater specificity after which time the Court will require the plaintiff to amend the group definition before it becomes necessary to do so.

(f) Further, the represented group members have potentially very large claims to damages for the reduction in the value of the their vehicles, under s 272(1)(a) of the Australian Consumer Law, provided that they can prove that the real or intrinsic value of their goods was less that the actual or average price of the goods at the time of supply.[7] Excluding those persons would cause substantive injustice.

(g) Adequate particulars of the 'defeat devices' have been provided and the case to be met is sufficiently clear. In assessing the defendants' complaints regard should be had to the fact that the defendants know the facts and the plaintiff does not.

15 The parties were in dispute about two questions of principle (whether a group definition must be framed in a way that will permit potential group members to determine whether they are caught by it, and whether a group definition may incorporate disputed elements of the claim). The principles are tolerably clear, but it is necessary to describe them in a little detail.

16 Section 33H of the Supreme Court Act provides:

(1) A group proceeding must be commenced by writ.

(2) The indorsement on the writ must, in addition to any other matters required by the Rules 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.

17 Compliance with s 33H is mandatory, as the statutory text makes plain. The section has been described as a 'gateway' provision[8] and a 'fundamental statutory requirement'.[9] The description of the represented group may only be amended with the court's leave (s 33K(1)).[10]

18 The statutory requirement is that the indorsement on the writ must 'describe or otherwise identify ...' the represented class. 'Describe' and 'identify' are words in common usage, of plain meaning. However, it is accepted that the provision (and specifically subsection 33H(2)(a)) is to be construed and applied having regard to the function that it is intended to perform within Part 4A.[11] In Petrusevski v Bulldogs Rugy Leage Ltd,[12] Sackville J said that in determining what s 33H(1)(a) of the Federal Court of Australia Act 1976 (Cth) (Federal Court Act) requires it is important to consider why it is necessary to describe or identify group members. I will return to this reasoning (which has been subsequently adopted by the Full Court of the Federal Court),[13] below.

19 Compliance with s 33H(1)(a) will ensure that the identity of the persons on whose behalf the group proceeding has been commenced (group members) will be ascertainable from the commencement of the proceeding.[14] Compliance with the provision also requires that during the currency of the class action it is possible to identify the members of the class with certainty.[15] The Full Court of the Federal Court has held twice recently, in the plainest of terms, that certainty as to class composition, the description of group members, is fundamental to the operation of Part IVA of the Federal Court Act (the statutory cognate of Part 4A of the Supreme Court Act).[16] In Ethicon Sarl v Gill,[17] the Full Court identified two related rationales for this conclusion, both derived from a purposive reading of the statutory scheme, namely that change to the composition of the class have important legal consequences for substantive legal rights[18] and that certainty of composition allows the Court to deal with the class when necessary for the purposes of the Part, as anticipated by ss 33J, 33L, 33Q, 33R, 33S, 33T, 33X and 33ZB (among other provisions).[19]

20 One aspect of the certainty required by statutory scheme is that group definitions must not operate in ambulatory fashion, allowing the composition of the class to change by the happening of an event post commencement.[20] Another is that the group definition, read with the pleading, must allow potential group members to reasonably ascertain whether they are members of the group. The latter aspect is in issue in this case. The reasoning in the cases considering that issue has been as follows.

21 In Petrusevski v Bulldogs Rugby League Ltd, the question before Sackville J was whether the group definition complied with s 33H(1)(a) of the Federal Court Act. The Bulldogs Rugby League Club was alleged to have engaged in misleading conduct by representing in various ways that it had complied with salary caps when it had not in fact done so. The group was defined as all persons who had suffered financial loss as a result of the conduct of the club alleged, by placing lawful wagers in the rugby league competition, who did not know of the salary cap breaches and expected the Bulldogs to comply with the salary cap. The Court accepted the submission that the conduct was pleaded in such vague and imprecise terms that it was impossible for an individual to determine even with advice, whether he or she had relied on the conduct and was therefore a member of the group. Sackville J reasoned that in determining what s 33H(1)(a) requires it is important to consider why it is necessary to describe or identify the group members. One reason is to allow the court to determine whether the requirements have been met;[21] another is to enable group members to decide whether or not to opt out. His Honour held that, 'what constitutes an adequate description or identification of the represented group for the purposes of s 33H(1)(a) must be determined by reference to the other provisions of Part IVA, in particular those concerned with the rights and duties of group members'.[22] Whilst it was open define the represented group by reference to conduct alleged in a pleading,[23] 'difficulty may arise if the pleading is so vague or uncertain that some potential group members cannot reasonably be expected to ascertain by reference to the pleading, whether they are in fact members of the group'.[24] His Honour said that a narrow or technical approach should not be taken in determining whether a pleading satisfies s 33H(1)(a) and that some latitude may be allowed to an applicant in pleading a representative action to take account of the special characteristics of such actions; it was '[not] necessary for the definition of a represented group to be so precise as to eliminate all possible ambiguity or room for argument.'[25]

22 In 2018 the Full Court of the Federal Court in Ethicon Sarl (Allsop CJ, Murphy and Lee JJ) also reasoned (in a different context) that certainty of composition of group membership allows the Court to deal with the class when necessary for the purposes of the Part.

23 In 2020 the Full Court in Dycyzynski v Gibson[26] (Murphy, Colvin and Lee JJ) expressly approved the reasoning in Petrusevksi, saying,[27]

[Section 33H] supports s 33C because it facilitates and an assessment by the Court about whether the specified threshold requirement have been satisfied, and also serves the purpose of enabling each class member to ascertain whether he or she is a member of the class, and to decide whether or not to opt out of the class action pursuant to s 33J: Petrusevski v Bulldogs Rugby League Club Ltd [2003] FCA 61 at [20]‑[22].

Through the description of the class in the originating application or the statement of claim it must be possible to identify with certainty the members of the class (although not necessary to name them or specify their number).

24 Also in 2020, in Wright Rubber Products v Bayer[28] the Full Court of the Federal Court (Moore, Jessup and Dodds‑Streeton JJ) heard an appeal from a decision striking out parts of the pleading including the group definition in a price fixing case. The group was defined as commercial manufacturers of rubber compounds and/or rubber products who during the period paid at least a stated monetary amount for rubber chemicals or rubber compounds. Rubber chemicals were defined by a list. Rubber compounds and chemicals were defined to mean compounds of natural or synthetic rubber and other raw materials that were manufactured using rubber chemicals; rubber products defined as intermediate or finished products manufactured using rubber compounds for manufacturers and consumers. The trial judge had found that the word 'using' was ambiguous and that the definition was defective because it did not allow group members to know whether they were caught by it. The Full Court disagreed. Moore J (with whom the others Judges agreed on this point[29]) held that the word 'using' had one meaning and was not ambiguous. Having done so, his Honour said,[30]

The fundamental statutory requirement is that the application (or some other document supporting the application) 'describe or otherwise identify the group members': s 33H(1)(a). This has been done in the present case, unambiguously. The fact that inquires might need to be made by a person uncertain of whether they are a group member does not deprive the description of objective criteria by reference to which membership or non‑membership may be established. This was the test applied by the Full Court in King v GIO .... If a person who may be a group member does not wish to ascertain whether they meet those criteria or is unable to do so but in any event does not wish to be involved in the proceedings, they can opt out of the proceedings. If a person who may be a group members is unable to ascertain whether they meet those criteria and wishes to prosecute with certainty a claim of the type being advanced by the applicant, that person can opt out and pursue an individual claim.

25 In the 2021 Federal Court decision in J Wibsey & Associates v UBS AG,[31] Beach J considered an application to strike out a group definition for non‑compliance with s 33H(1)(a). His Honour stated the applicable principles in these terms:[32]

Section 33H(1)(a) of the Federal Court Act 1976 (Cth) requires that an application commencing a representative proceeding describe or otherwise identify the group members to whom the proceeding relates. But no unduly narrow or technical approach should be taken to this requirement. It should be construed and applied bearing in mind the function that it is intended to perform under Pt IVA.

Group members must be described or identified so that they can be notified of the proceeding and can decide whether to opt out pursuant to s 33J. Another function of s 33H(1)(a) is so that the Court can identify who is bound by any judgment for the purposes of s 33ZB.

The pleading must not be so vague or uncertain that potential group members cannot reasonably ascertain whether they are members of the group. A group definition should not give rise to significant uncertainties and ambiguities in this respect.

Some practical questions may be posed. Is the description such as to reasonably enable a person, with the assistance of a legal adviser if necessary, to ascertain whether he is a group member? And if the description incorporates a reference to conduct alleged in the pleadings, can a person or his adviser, by reading the description and the relevant portion of the pleadings, reasonably determine whether he is a group member? If the answer is no to either or both questions, the definition is unlikely to satisfy s 33H(1)(a). But clearly, the fact that inquiries might need to be made by a person who is uncertain of whether they are a group member does not deprive the description of objective criteria by reference to which membership can be established. And the fact that potential group members may need to make inquiries to ascertain whether they fall within the group definition does not render that definition inadequate for the purposes of s 33H(1)(a). (emphasis added)

26 With respect, I agree with and adopt Beach J's synthesis of the principles, which is consistent with the decisions that preceded it. In 2023 in Green v Graincorp Oilseeds,[33] John Dixon J of this Court adopted and approved the statement of principle in J Wibsey.

27 Most recently, in 2025, the Full Court of the Federal Court in Impiombato v BHP Group Limited[34] (Beach, Lee and O'Bryan JJ) had to determine the proper interpretation of a group definition. Beach and O'Bryan JJ reiterated that one of the statutory purposes of s 33H is 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, citing Petrusevski for the latter proposition,[35] saying,

... certainty as to 'class composition', the description of group members, is fundamental to the operation of Part IVA, as observed by the Full Court in Ethicon Sarl 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] FCAFC 120; (2020) 280 FCR 583 at [170] (Murphy and Colvin JJ) and [335] (Lee J).[36]

28 The plaintiff in this case relied upon the words in the passage from Wright Rubber set out above, that 'if a person who may be a group members is unable to ascertain whether they meet those criteria and wishes to prosecute with certainty a claim of the type being advanced by the applicant, that person can opt out and pursue an individual claim', to support her proposition that s 33H(2)(a) 'does not require group members to know that they are group members'. The words relied upon do not support the proposition advanced by the plaintiff, and should not be understood divorced from their context, in which the Court held that the group definition was not ambiguous. The Court's reasoning was that the need for a potential group member to make inquiries about whether their circumstances were caught by the definition, and the mere possibility that there may be some group members who have difficulty making or concluding those inquiries, did not deprive the description of its objective criteria by which membership may be established. Wright Rubber does not stand for the proposition that whether a group definition reasonably permits a potential group member to ascertain whether they are caught by it is irrelevant when assessing its compliance with s 33H(2)(a). To the extent that the plaintiff sought to derive that proposition from that case, they did not say how it could be reconciled with the other authorities discussed here.

29 As Sackville J in Petrusevski and Beach J in J Wibsey accepted, there must be tolerance for some ambiguity but the pleading must not give rise to significant uncertainties and ambiguities in that respect.

30 The thread of principle that runs through the authorities is that to comply with s 33H(2)(a) the group definition, read with and in the context of the pleading, must be capable of fulfilling (i.e. be reasonably adapted to achieving) its statutory functions. If a proffered group definition (read with the pleading) appears to provide a 'description' or 'identification' of group members but is not reasonably capable of fulfilling those functions it will not comply with s 33H(2)(a). A group definition that is reasonably capable of achieving its functions need not eliminate all traces of ambiguity. A purposive reading of s 33H permits a court to evaluate whether a group definition is adequate for its statutory purposes. One of those purposes concerns the right of group members to opt out (s 33J) which is fundamental to the operation of Part 4A[37] and the correlative requirement that the Court fix a date by which group members must opt out (s 33Y) and the provision of notice for that purpose (s 33X).

31 I do not accept the plaintiff's submission that the 'primary' purpose is to facilitate the Court's assessment of whether the threshold requirements specified in s 33C have been satisfied and a 'secondary' purpose is to enable group members to ascertain whether they are members of the class, with the consequence compliance with s 33H(2) cannot be determined by considering whether the definition allows affected people to determine whether they are group members. When regard is had to the provisions of Part 4A that concern group members' rights and duties, it is evident that a group definition must be adequate for both the Court and group members to ascertain who are the persons on whose behalf the proceedings are brought. Part 4A affords group members certain rights or opportunities to take steps or seek orders from the Court: the right to opt out (s 33J), the opportunity to apply to represent the interests of group members (s 33T) the opportunity to seek to have an individual question determined (s 33R). Part 4A does not specify when, during the life of proceedings, the right to take any step may be exercised. For the purpose of taking any step, a group member must be able to reasonably ascertain whether they are in fact a group member. At the same time, the Court, in dealing with group members and their interests, including in response to any application by a group member, must have certainty about the composition of the class. By way of example, as the plaintiff accepted, there must be certainty about class composition by the time the Court issues any judgment in a proceeding, as required by s 33ZB. Whilst in the usual course a judgment would not be issued until late in the life of a proceeding, that will not universally be the case. Summary judgment is an obvious exception to the usual course. The statutory scheme evinces an intention that there be certainty about group composition throughout the proceeding, for all purposes.

32 It follows that I do not accept that proposition that the point in time at which a group definition must be sufficiently clear is essentially a question of case management. For the statutory scheme to function coherently, the Court needs to be in a position to exercise its powers without being in doubt about class composition, and affected persons need to be in a position to know whether they are group members. The plaintiff's position in respect of the issue of notices to potential group members (discussed below), illustrates one of the difficulties that arises where class composition is uncertain. It may be necessary at any stage of a group proceeding for the Court to issue notices to group members and in doing so, to be confident of who they are.

33 I also reject the proposition that the adequacy of the group definition should be determined by reference to discretionary considerations. Whether a group definition is adequate is to be determined by its content, read in the context of the associated pleadings.

34 Separately, the defendants relied upon dicta in Perera v GetSwift[38] to support a contention that it is impermissible to include within a group definition, a criterion that turns on a resolution of a central issue in the case. The submission was made diffidently, the defendants acknowledging that the dicta was inconsistent with other authority. The defendants had mind the reference in this case to the existence of defeat devices in 'affected vehicles', in the group definition. The problem in this case was said to lie in the fact the presence of defeat devices in Mercedez‑Benz vehicles was a central issue in dispute requiring resolution and also one that may not be resolved even until after the trial of the common issues. That was so for reasons including the nature of the alleged devices which, as defined, encompassed an 'unbounded' number of design elements. The facts in this case are addressed later in these Reasons, but I will first address the broad question of principle.

35 In Perera v GetSwift, Lee J determined a three‑way multiplicity contest in which the parties said that their defined classes perfectly overlapped. Lee J said that a 'logical difficulty' presented itself in that minor differences in the way the pleaded conduct was described meant it was 'at least logically possible' that loss or damage may have been suffered by one group member arising from only one elements of the alleged conduct and not the other.[39] His Honour said that was an illustration of 'a broader logical problem, largely ignored, but which is inherent in this sort of subjective, causative element to a group definition', namely that, 'at no stage is it possible to assert with certainty that a particular claimant is, in fact, a group member as defined by reference to all criteria specified. This must be the case because in the event that it is ultimately found, following a determination of individual issues, that no loss and damage has suffered by the claimant as pleaded, it follows inexorably that the claimant is not, and has never been, a group member as presently defined.' Lee J went on to say that it is necessary to be able to identify the persons whose claims are the subject of the class action at all times during the currency of the action. His Honour acknowledged Wilcox J in Nixon v Philip Morris and Moore J in King v GIO had found that defining group membership by reference to a loss and damage criterion was unobjectionable and, in any case, decided the case before him on the basis of the parties' assumption.

36 The 'collapsing class' theory was rejected by Wilcox J in Nixon v Philip Morris,[40] by Moore J at first instance in King v GIO [41] also, more significantly, by the Full Court of the Federal Court (Wilcox, Lehane, Merkell JJ) in King v GIO (upholding Moore J on this issue).[42] There, the group definition was in issue, the group having been defined as those who did not accept a takeover offer because of the defendant's conduct and who suffered loss and damage as a consequence. The Full Court held that it was incorrect to say that the class was defined by reference to 'potential outcomes' in the litigation. It held that, 'rather, the group is defined by reference to matters that are capable of being objectively ascertained, namely GIO share ownership, non‑acceptance of the AMP offer by reason of certain conduct and loss suffered as a consequence. If it should transpire that there was no such conduct or that it did not cause any loss, the group members' claims will fail.'[43] The position established by King v GIO was accepted implicitly in Beach J's summary of the principles in J Wibsey set out above.

37 I am bound by the Full Court's reasoning in King v GIO (the defendants did not explain why I should not follow it) and as it happens I agree with it. At the level of principle I am not troubled in the way that Lee J was, with the apparent 'logical difficulty' that arises when a group definition incorporates a causation element.

38 The crux of the point raised by the dicta in Perera v GetSwift is that if a criterion of group membership is a matter in contest and that matter is ultimately determined adversely to the plaintiff (for example that the conduct of the defendant did not cause any loss or that conduct did not in fact occur) that criterion will not ultimately be met, with the consequence that group members described by that criterion will never have been group members. Although the 'collapsing class' argument is concentrated on the inclusion of a causation element in a group definition, it would apply conceptually or as a matter of logic, to any matter that was in contest, whether of major or minor significance.

39 A necessary touchstone in considering what s 33H(2)(a) of the Supreme Court Act requires, is the fact that the section is concerned with what must appear in the indorsement on the writ, understood by reference to the pleadings. Accordingly, where a group definition incorporates a matter in contest in the proceedings as a criterion (stating it as though it were an established fact or conclusion), it may be taken as a reference to that which is alleged in the proceeding. As John Dixon J said in Green v Graincorp Oilseeds,[44] whether a pleading complies with ss 33C and 33H(2) is to be determined on the presumption that the allegations in the pleading can be established at trial.

40 What makes group membership relevantly certain is not that the fact that nothing about the description of that group is subject to future determination, but that it is clear, from the pleading (whether the definition by itself or read with the pleading) that the claims in the pleading are made in respect of a defined group of people. As the Full Court reasoned in King v GIO, a group defined by reference to matters that are alleged, is defined by matters that are capable of being objectively ascertained.

41 Although it is true that a represented group comprises persons and not the claims of persons,[45] a group definition that conforms with s 33H(2)(a) will necessarily be addressed to the relationship between persons and claims. That is because those persons described or defined are those on whose behalf the proceeding has been commenced, which means those on whose behalf the claims in the proceeding are made. Whether the characteristic that links the persons otherwise described to the claims that are made appears in the group definition or the pleading, should not matter. It might be possible in some cases to describe those people without apparently referring to an element of the claim where it is apparent from the pleading that a claim is made on behalf of those people. For example, in shareholder class actions for breaches of continues disclosure laws it is not uncommon that group membership is defined by reference to persons who acquired or held interests in shares in the subject company during the relevant period. A definition of that kind defines or describes the group members to whom the proceeding relates because, by reference to the pleadings, it is clear that claims are made on behalf of all such shareholders. Were claims not in fact advanced for all such shareholders a definition in that form would not comply with s 33H(2)(a) because it would not describe those persons to whom the proceeding relates. It would describe a wider group, of whom group members were only a sub‑set. In other kinds of case it may be more difficult to sensibly define a represented group without making reference to individual causation.[46]

42 The reasoning in Dyczynski v Gibson[47] is instructive, notwithstanding that the issue before the Court was whether the appellants were group members, rather than a challenge to a group definition. The proceeding was brought by and for representatives of passengers killed in the shooting down of the aircraft MH17 in the Ukraine. Elements of the group definition reflected the criteria upon which an Australian Court would have jurisdiction to determine a claim under article 33 of the Convention for the Unification of Certain Rules for International Carriage by Air. A submission was made that the appellants were not group members because their circumstances did not fall within any of the categories under article 33 which were picked up in the definition. The Court held that they were group members. Discussing s 33C(1)(a), Murphy and Colvin JJ held that the evidence showed that there were facts which may ground the appellants having a right of entitlement to relief under one limb of the class definition. Their Honours said that that the fact that they might not succeed at trial in showing that they fell within that paragraph did not mean that they did not have a bona fide claim to do so.[48] While the 'claims' (to which s 33C) refers must be of a type which is recognisable at law, the mere fact that they ultimately do not succeed at trial does not mean that they do not have that character at the commencement of the action. Unless the claims are not made in good faith or otherwise constitute an abuse of process, uncertainty as to whether they will ultimately be made out does not mean that they fall outside the meaning of s 33C.[49] On the reasoning in Dyczynski then, the appellants were group members on the basis of the matters they alleged, and notwithstanding that they might ultimately fail to prove those matters.

43 Their Honours went on to say that s 33H supports s 33C because it facilitates and an assessment by the Court about whether the specified threshold requirement have been satisfied, and also serves the purpose of enabling each class member to ascertain whether he or she is a member of the class, and to decide whether or not to opt out of the class action pursuant to s 33J_._ Through the description of the class in the originating application or the statement of claim it must be possible to identify with certainty the members of the class.[50] In my view, in the same way that s 33C is concerned with matters alleged, so too, is s 33H.

44 It is evident from the structure of paragraph 1 that the plaintiff intends to distinguish between those group members who acquired vehicles of the kind described in Annexure A to the ASOC and those described by sub‑paragraph 1(a)(ii) (who it designates, the 'unspecified engine group members').

45 Paragraph 1 (which contains both limbs of the group definition) employs the definition 'Affected Vehicles' which denotes those Mercedes Benz diesel vehicles which are of the same engine type as the plaintiff's second vehicle as set out in Annexure A (sub‑paragraph 1(a)(i)), and those which contained, from the time of supply, one or more of the defeat devices as defined in paragraph 25 (sub‑paragraph 1(a)(ii)).

46 If the first limb of the group definition in this case is excised leaving only sub‑paragraph 1(a)(ii), the group members are:

All persons who [in the relevant period] acquired from the first Defendant or one of its retailers or Dealers in Australia, an equitable or legal interest (including under a hire‑purchase agreement, but excluding a mere leasehold interest) in a Mercedes‑Benz diesel vehicle which contained, from the time of supply, one or more of the Mercedez defeat devices as defined in paragraph 25 below.

47 On its face, the definition in sub‑paragraph 1(a)(ii) describes those group members to whom the proceedings relates, in that it states that they are they are those persons who, in the period, acquired an interest in a Mercedes‑Benz diesel motor vehicle which contained a Mercedes Defeat Device at the time of supply. A group member would readily conclude from sub‑paragraph 1(a)(ii) that if their interest in a Mercedes‑Benz diesel vehicle was acquired in the relevant period and if that vehicle contained a defeat device, they are a group member.

48 However, the definition (even when read with the pleading) does not in fact permit a group member (or the Court, for that matter) to discern which vehicles are alleged to have contained defeat devices, and accordingly, which persons (those who acquired an interest in such motor vehicles) are group members. By 'which vehicles', I should not be read as saying that the affected vehicles must be individually identified or that there is only one way in which they could be described (whether by reference to engine type, by the period in which they were sold, or by some other identifying feature).

49 The group definition refers to paragraph 25 of the pleading which reads,

From the time of supply the plaintiff's second vehicle contained, and further, the Affected Vehicles contained one or more of the following elements of design, which individually and further in combination, constituted a Defeat Device, as pleaded in paragraphs 25A and 25B below (Mercedes Defeat Devices).

50 When refence to the plaintiff's vehicle and those vehicles described in Annexure A are excised the allegation at paragraph 25 is that the 'Affected Vehicles' contained defeat devices. 'Affected Vehicles' is given content only by paragraph 1. Reading sub‑paragraph 1(a)(ii) and paragraph 25 together, the allegation at paragraph 25 is in substance that those vehicles which contained at the time of supply, one or more of the alleged defeat devices, contained the alleged defeat devices. On the question of the identification of which vehicles are the subject of the claim (and accordingly, which persons are group members), the pleading is entirely circular. Nowhere else in the pleading is there found a description of the Affected Vehicles that would solve that problem.

51 In theory, that difficulty could be resolved by reference to the description of the Mercedes Defeat Devices. However, for the reasons that the defendants submitted, the description in paragraphs 25A and 25B does not on any reasonable view, solve that problem. The plaintiff did not contend that a group member (or any person or the Court) could discern by reference to the descriptions of the defeat devices, which vehicles were Affected Vehicles. In brief:

(a) the pleading states[51] that Australian Design Rule 79 (ADR79)[52] applied to the Affected Vehicles, and sets out the 'defeat devices' as provided in ADR79. That definition is:

any element of design which senses temperature, vehicle speed, engine rotational speed, transmission gear, manifold vacuum or any other parameter for the purpose of activating, modulating, delaying or deactivating the operation of any part of the emission control system, that reduces the effectiveness of the emission control system under conditions which may reasonably be expected to be encountered in normal vehicle operation and use.

(b) the ADR79 definition then, defines defeat devices as elements of design which have the features and effects described in the rule. At paragraphs 25A and 25B several elements of design are set out: cycle detection and alternative mode, thermal detection, exhaust mass limit detection, SCR temperature detect, AdBlue (urea) closing detection, Nox mass flow, intake air temperature, restart protection, engine start temperature;

(c) the lists of design features are said not to be comprehensive;

(d) the Mercedes Defeat Devices are said to have been constituted by one or more of the alleged elements of design, individually or in combination;

(e) the design feature are highly technical;

(f) it is said that the plaintiff does not know whether her vehicle contained certain of the particular design features alleged.

52 The defendants correctly submit that the universe of alleged design elements is unbounded and the definition of defeat devices is generic and contains elements susceptible to interpretation. It must be observed that the broad‑ranging and imprecise descriptions of the features of the alleged defeat devices arise at least in part from the breadth of the statutory definition in ADR79, and the fact that by the nature, defeat device are concealed - i.e. they are not intended to be to be readily discoverable. The technical nature of the allegations is inherent in the subject matter. The plaintiff said that the presence of a defeat device in a vehicle could be detected by prohibitively expensive testing. It was not contested that the description of 'defeat device' in a pleading would not reasonably allow the ascertainment of which vehicles were Affected Vehicles, for the purposes now in issue.

53 The plaintiff emphasised the fact that the defendants are in position to know whether their vehicles contain defeat device and that to directly identify a defeat device requires a person to access and interpret the proprietary computer code of a vehicle's engine control unit. The plaintiff has, in the case of the first limb of the group definition, identified vehicles that it alleges contain defeat devices, by engine type. That has been done in a way that has not raised objection and which satisfies the requirements of s 33H(2)(a). That appears to have been achieved by inference from certain evidence that the plaintiff possesses. There might also be other ways of sufficiently describing affected vehicles (and therefore describing the represented group). The difficulty in detecting the presence of defeat devices does not relieve plaintiff of the obligation to adequately define the group of persons she purports to represent.

54 The group definition in this case is an example of a definition that, prima facie, is a description of the represented group but which is in fact not reasonably capable of achieving its statutory functions, in the sense that those functions were discussed earlier.

55 For completeness, it follows from the discussion of the applicable principles that I do not accept the defendants' argument that even if the description of defeat devices were clarified, the group definition would remain defective on the basis of the issue discussed in the dicta in Perera v GetSwift.

56 The remaining points made by the plaintiff are addressed at the level of principle, earlier in these Reasons. I will say something briefly about the practicalities.

57 The plaintiff submitted that notices under s 33X are not typically given personally and could be given to all members of the broadest possible class, for example, 'all buyers of Mercedez‑Benz vehicles within the relevant period_, without positively identifying its constituents_'. Such a notice would be a notice to persons who might be group members in circumstances were it is not possible to say, from the pleadings, whether they are or are not group members. Is it doubtful that such a notice would comply with s 33X(1)(a).

58 Next, the plaintiff raised the undesirable prospect of multiple applications for preliminary discovery. The spectre of preliminary discovery is not a principled reason to allow a claim to be advanced in circumstances where there is in fact insufficient material available to the plaintiff to make a claim on a proper basis on behalf those persons, including where (if it were the case) there was no proper basis to allege that vehicles beyond those in Annexure A contained defeat devices. Whether that is so in this case remains to be seen on any attempted repleading. I raise this issue because it was addressed in the plaintiff's submission, noting that the present application is (by the defendant) for the striking out of the pleading and (by the plaintiff) for leave to replead. Further, the objective of avoiding multiplicity is not to be pursued divorced from the fundamental requirements of the statutory scheme, and nor is it required that the Court take whatever steps are needed to cover as many potential group members as possible.[53]

59 Similar observations may be made of the plaintiff's submission that persons who the plaintiff wishes to represent might have potentially large claims to damages should they succeed. That is not determinative of the question whether the plaintiff's pleading is adequate.

60 The defendants sought to strike out the allegations concerning the 'Mercedes Defeat Devices' in ASOC paragraphs 25A to 25B and alternatively sought further and better particulars sufficiently detailed to put the defendants on notice of the case to be met.[54] They submitted that the allegations that the Affected Vehicles contained defeat devices were the foundational premise of the allegations of wrongdoing, including that the defendants knew that the vehicles contained defeat devices but did not disclose that fact to the Federal Government, and that they engaged in unconscionable conduct. Accordingly, the 'Mercedes Defeat Devices' must be precisely defined. They made three complaints:

(a) first, the definition of Mercedes Defeat Devices is convoluted, technical and ambiguous;

(b) second, the pleas in paragraph 25A do not identify the case to be met, the 'identified defeat devices' being largely premised on matters said not to be currently known to the plaintiff;

(c) third, the nature of the 'unidentified defeat devices' in paragraph 25B is even more unclear. There is no material plea as to what elements of design are said to constitute a defeat device, nor how they are said to constitute a defeat device. The plaintiff expressly states in the particulars to that paragraph that she is 'not in a position to identify the unidentified defeat devices.' Insofar as she seeks to make a case based on inferences, the inferences are entirely unclear.

61 The plaintiff submitted that the allegations in paragraph 25A are plainly intelligible to the defendants. The technical nature of the definitions of the devices is inherent in the subject matter and reflects the statutory definition in ADR79. The case to be met is sufficiently clear. In relation to paragraph 25B it is true that the allegation is made at a level of generality but the plaintiff has nevertheless pleaded and particularised a sound basis for the proposition that 'Mercedes had incorporated other defeat devices in its diesel vehicles'. The particulars of those devices are within the defendants' knowledge and the only way to identify them comprehensively with the level of precision the defendants demand is by reference to the software code of the relevant engine control units held by the defendants.

62 The relevant principles include the following:[55]

(a) the function of a pleading in civil proceedings is to alert the other party to the case they need to meet (and hence satisfy basic requirements of procedural fairness) and further, to define the precise issues for determination so that the Court may conduct a fair trial. Pleadings, when well‑drawn, serve the overarching purpose of the Civil Procedure Act 2010 (Vic);

(b) every pleading must contain in a summary form a statement of all material facts upon which the party relies, but not the evidence by which the facts are to be proved (r 13.02(1)(a));

(c) it is not sufficient to simply plead a conclusion from unstated facts. In this instance the pleading is embarrassing;

(d) a pleading must be presented in an intelligible form - it must not be vague or inconsistent. Thus a pleading is embarrassing within the meaning of r 23.02 when it places the opposite party in the position of not knowing what is alleged. The fact that a pleading arises from a complex factual matrix does not detract from the pleading requirements. To the contrary, the requirements become more poignant;

(e) a party who alleges a condition of mind must state in the pleading the material facts upon which the party relies.[56] Knowledge may be pleaded by reference to facts and circumstances from which it may be inferred that the relevant party had the knowledge, provided the inferences are reasonably arguable;[57]

(f) a pleading which involves an allegation as serious as unconscionable conduct demands a particular degree of clarity and precision;[58]

(g) particulars are not intended to fill gaps in a deficient pleading. They serve a distinct purpose - to enable the other party to plead, clarify and confine the scope of issues, and to avoid the other party being surprised at trial. They are intended to fill in the picture of the plaintiff's cause of action (or defendant's defence) with information sufficiently detailed to put the other party on guard as to the case that must be met;

(h) a party's right to be apprised of the nature of its opponent's case before trial must be accommodated to the nature of the case. In some cases a plaintiff will only be in a position to allege facts from which inferences may be drawn;[59]

(i) in circumstances where the defendant has exclusive knowledge of relevant facts or exclusive possession of documents it is commonly accepted that the requirement for the plaintiff to give particulars may be postponed until after discovery, subject to the requirement that the plaintiff must have proper basis for the allegations made in a pleading with the best particulars the plaintiff can give;[60]

(j) in considering whether to strike out a statement of claim as embarrassing the Court should keep steadily in mind that there are other interlocutory process subsequent to the pleadings which continue to perform and progress the function of informing the other side of the case to be met at trial;[61]

(k) in considering objections on the ground of embarrassment:[62]

The Court should stand back and consider the pleading as a whole and in that light ask: does the case alleged give clear notice of the case to be met at trial?

This modern approach to applications to strike out pleadings on the ground that they are embarrassing is reflected in this Court's decision in CA Ballan, where the Court stated that, while important, pleadings are primarily used 'to help the parties define the real issues in dispute', while bearing in mind that pleadings are 'procedural tools only' (citations omitted);

(l) the power to strike out a pleading is discretionary. As a rule, the power will be exercised only when there is some substantial objection to the pleading complained of or some real embarrassment is shown.

63 In my view the allegations in paragraph 25A are sufficiently pleaded for present purposes, having regard to the following considerations:

(a) The plaintiff's case is concerned with the presence of defeat devices that meet the statutory definition contained in ADR79. The rule defines defeat devices by reference to 'elements of design' which have the features described (including elements which sense temperatures, vehicles speed or other parameters for the purpose of activating, modulating, delaying or deactivating the operation of any part of the emission control system) and the effect described: reducing the effectiveness of the emission control system under normal driving conditions. The rule itself refers to technical aspects of vehicles design and, as the defendants submit, may leave room for interpretation, but is not incomprehensible and could not be fairly understood as such, particularly from the perspective of a vehicle manufacturer.

(b) Paragraph 25A identifies with reasonable clarity, the elements of design that the plaintiff says constitute defeat devices. Each sub‑paragraph identifies a specific alleged device and describes its operation in an intelligible way, notwithstanding that some elements are said to be not within the plaintiff's knowledge. The elements are alleged as material facts. The particulars incorporated into that paragraph appear to have been a response to matters raised by the defendants. The fact the plaintiff cannot answer the defendants' requests at this point in proceedings because the plaintiff does not know, for example, the mechanisms by which the devised operate, does not detract from the fact that the elements upon which the plaintiff relies have been identified.

(c) I do not consider that the level of detail presently provided is embarrassing in the sense that it does not allow the defendants to know the case that it has to meet, having regard to the principle set out above, in circumstances in which the design features of Mercedes‑Benz motor vehicles are known to the defendants.

(d) It is said that the Mercedes Defeat Devices contained 'one or more' of the itemised elements of design. The fact that the pleading allows that the devices might have contained multiple design elements (in a combination that the plaintiff cannot identify) lends complexity to the claim but it does not in a relevant sense, at this stage of the proceeding, mean that the defendants cannot understand the case which, by reference to paragraph 25, is limited to the particular design elements described.

(e) The defendants are right to emphasise the centrality of the 'defeat device' allegations to the case as a whole, and to say that where allegations of knowledge and unconscionability are made, precision is required. However, what is required is that the defendants know the case that is to be met. Where unconscionability is alleged, each element of the cause of action needs to be properly pleaded and particularised, and an applicant must explain why the facts and circumstances stated lead to the conclusion contended for, in a coherent way, anchored in the facts.[63] The defendants did not make a broad complaint about the way that the unconscionability allegations are made but instead said only that the defeat devices need to be precisely defined. That element of that cause of action has been sufficiently pleaded at this stage of the proceeding. The requirement for precision where allegations of impropriety are made does mean that the Court should not take into account when assessing the degree of particularisation provided at an early stage of the proceeding, the principle set out at sub‑paragraphs 62(h)‑(l) above.

64 In contrast, I consider that paragraph 25B is confusing and does not apprise the defendant of the case to be met. It is embarrassing, and will be struck out. In particular:

(a) By that paragraph the plaintiff is endeavouring to allege the existence of further elements of design, by inference from other facts including an expert report published in 2020. Alleging a fact in that way is not objectionable by itself.

(b) However, the paragraph is inherently confusing. It is said that the Mercedes Defeat Devices included elements of design other than the 'identified defeat devices' (i.e. those alleged in paragraph 25A). That is the only allegation of material fact in respect of the so‑called 'unidentified defeat devices'. It is said by way of particulars that the existence of the 'unidentified defeat devices' is to be inferred from the matters set out. The particulars refer to four design elements. It is then said that the plaintiff is 'not in a position prior to discovery, to identify the unidentified defeat devices'. Because of the inconsistent nature of the allegations and particulars it is in a real sense unclear whether the plaintiff is intending to say that the design elements identified comprise the 'other' defeat devices upon which the plaintiff relies, or to say something else. The vagueness and ambiguity of the pleading is compounded by the statement in particulars that the identified defeat devices (i.e. those described in paragraph 25A) are 'not comprehensive of all Defeat Devices in the Affected Vehicles.' The problem is compounded further by the context in which the allegation at paragraph 25A are made. It will be recalled that the 'Affected Vehicles' said to contained the Mercedes Defeat Devices are, by reason sub‑paragraph 1(b)(ii), defined in a circular way. Reduced to its essentials, the plaintiff appears to be attempting to make a case that some Mercedes Benz diesel vehicles (it cannot say which) contained unknown defeat devices. That part of the plaintiff's case (paragraph 25A, by itself and also when read with sub‑paragraph 1(a)(ii)) does not fairly put the defendant on notice of the case it has to meet, even allowing for the fact that the proceeding is at an early stage. The starting point for an acceptable pleading, even at an early stage, is the allegation of material facts in a manner that makes the case to be met, sufficiently clear. That has not occurred in the respects identified. Once that occurs, the adequacy of the particularisation provided, can be assessed.

(c) More broadly, the distinction between 'identified defeat devices' and 'unidentified defeat devices' is confusing. In a case where the existence of defeat devices is the foundational allegation, the significance of any classification of the alleged devices into categories needs to be clear. In this case it is not. Certain allegations in the balance of the pleading are made only in respect of the 'identified' devices (for example, those at paragraphs 27, 90(b), (c), (j)). The various allegations of legal wrongdoing are nevertheless made in respect of vehicles containing the Mercedes Defeat Devices, both identified and 'unidentified'.

[2] I will use the expression 'Amended Statement of Claim' notwithstanding that some of the parts of the pleading now in issue were 'amended' without leave and are in that sense, a proposed pleading.

[4] The seventh paragraph in the ASOC, numbered [1].

[5] A group definition is to be construed objectively, considering its words in context, rather than subjectively from the position of the parties: Impiombato v BHP Group Limited [2025] FCAFC 9, [55] (Impiombato).

[6] Ridge v Hays Specialist Recruitment (Australia) Pty Ltd [2022] FCA 1613, [12].

[7] Citing Williams v Toyota Motor Corporation Australia Ltd [2024] HCA 38.

[8] Ethicon Sarl v Gill [2018] FCAFC 137; (2018) 264 FCR 394, [7] (Ethicon Sarl).

[9] Wright Rubber Products Pty Ltd v Bayer AG [2010] FCAFC 85, [34] (Wright Rubber).

[10] See the principles as discussed in Mumford v EML Payments Ltd [2025] VSC 203.

[11] J Wisbey & Associates Pty Ltd v UBS AG [2021] FCA 36, [22]; Petrusevski v Bulldogs Rugby League Ltd [2003] FCA 61, [19] (Petrusevski).

[12] Petrusevski v Bulldogs Rugby League Ltd [2003] FCA 61.

[13] Dyczynski v Gibson [2020] FCAFC 120; (2020) 280 FCR 583 (Murphy, Colvin and Lee JJ), [170] (Dyczynski); Impiombato, [53].

[15] Dyczynski, [171] (citing Ethicon Sarl, [37] (Murphy and Colvin JJ), [335] (Lee J)).

[16] Impiombato, [53]; Ethicon Sarl, [37]-[38].

[17] Ethicon Sarl v Gill [2018] FCAFC 137; (2018) 264 FCR 394.

[20] See for example, Ethicon Sarl, [37].

[21] Petrusevski, [19], citing Wong v Silkfield Pty Ltd [1999] HCA 48; (1999) 199 CLR 255.

[23] Petrusevski, [24], citing King v GIO Australia Holdings Ltd [2000] FCA 1543.

[26] Dyczynski v Gibson [2020] FCAFC 120; (2020) 280 FCR 583.

[27] Dyczynski, [170]-[171], citing Ethicon Sarl v Gill [2018] FCAFC 137; (2018) 264 FCR 394, [37].

[28] Wright Rubber Products Pty Ltd v Bayer AG [2010] FCAFC 85.

[31] J Wibsey & Associates Pty Ltd v UBS AG [2021] FCA 36 (J Wibsey).

[33] Green v Graincorp Oilseed Pty Ltd [2023] VSC 395, [28].

[34] Impiombato v BHP Group Limited [2025] FCAFC 9.

[37] See Mobil Oil Australia Pty Ltd v Victoria (2002) 211 CLR 1, [50]; Timbercorp Finance Pty Ltd (in liq) v Collins [2016] FCA 44; (2016) 259 CLR 212, [126] (Gordon J); Tomlinson v Ramsey Food Processing Pty Ltd [2015] HCA 28; (2015) 256 CLR 507, [40].

[38] Perera v GetSwift Ltd [2018] FCA 732; (2018) 263 FCR 1 (Perera v GetSwift).

[39] Perera v GetSwift, [78]-[79].

[40] Nixon v Philip Morris (Australia) Ltd [1999] FCA 1107; (1999) 95 FCR 453, [126]-[127]; overturned by the Full Court in Philip Morris (Australia) Ltd v Nixon [2000] FCA 229 on other grounds.

[41] King v GIO Australia Holdings Ltd [2000] FCA 617; (2000) 100 FCR 209, [44]-[45].

[42] King v GIO Australia Holdings Ltd [2000] FCA 1543, [11].

[43] King v GIO Australia Holdings Ltd [2000] FCA 1543, [11].

[44] Green v Graincorp Oilseeds Pty Ltd [2023] VSC 395, [30].

[45] As the Full Court of the Federal Court said in Ethicon Sarl at [25], adopting Lee J in Dillon v RBS Group (Australia) Ptd Ltd (2107) [2017] FCA 896; 252 FCR 150, [50].

[46] As Wilcox J recognised in Nixon v Philip Morris (Australia) Ltd [1999] FCA 1107; (1999) 95 FCR 453, above.

[47] Dyczynski v Gibson [2020] FCAFC 120; (2020) 280 FCR 583.

[49] Dyczynski, [168] and the authorities cited there.

[50] Dyczynski, [171], citing Ethicon Sarl at [37]. Lee J similarly held that the appellants were class members when the class action was commenced and they remain class members after the amendment to the class definition, at [182].

[52] Promulgated under Vehicle Standard (Australian Design Rule 79/01 - Emission Control for Light Vehicles) 2005 (Cth); Vehicle Standard (Australian Design Rule 79/02 - Emission Control for Light Vehicles) 2005 (Cth); Vehicle Standard (Australian Design Rule 79/03 - Emission Control for Light Vehicles) 2005 (Cth); and Vehicle Standard (Australian Design Rule 79/01 - Emission Control for Light Vehicles) 2005 (Cth).

[54] The defendants submissions referred to a request for particulars previously made in correspondence with the plaintiff but said that particulars of the material allegations had not been provided. The pursuit of particulars in the application was not addressed with any more specificity.

[55] See Uber Australia Pty Ltd v Andrianakis [2020] VSCA 186; (2020) 61 VR 580 (Andrianakis), [50] citing Wheelahan v City of Casey & Ors [2013] VSC 316. The principles described here are taken from that passage in Andrianakis unless otherwise indicated.

[57] Webster v Murray Goulburn Co-op Co. Ltd (No 2) [2017] FCA 1260, [6].

[58] JB Asset Management v LBA Capital Pty Ltd [2023] VSC 183, [36] citing Teddo Corporation Pty Ltd v Owners Corporations No 1 [2022] VSC 667, [53]-[58].

[59] Andrianakis, [55]-[56] and the cases cited there.

[60] See Murphy v Victora (2004) 45 VR 119 and the authorities discussed there.

[62] Andrianakis [52]-[53], and the cases cited there.

[63] JB Asset Management v LBA Capital Pty Ltd [2023] VSC 183, [36] citing Teddo Corporation Pty Ltd v Owners Corporations No 1 [2022] VSC 667, [53]-[58].