Marsh Limited v Greensill Bank AG [2025] FCAFC 196

1. The applicants and prospective appellants, Marsh Limited and Marsh Pty Ltd (together, Marsh), sought leave to appeal on four grounds from the judgment and order made by the primary judge on 10 October 2025: Greensill Bank AG v Insurance Australia Limited (Anti-Anti-Suit Injunction Application) [2025] FCA 1241 (PJ). The primary judge granted anti-anti-suit relief against Marsh restraining them from pursuing or renewing claims for relief in the High Court of Justice in England and Wales (English Court) against Greensill Bank AG and Dr Michael C Frege in his capacity as Insolvency Administrator of Greensill Bank AG (together, GBAG) in relation to certain letters of engagement (English Proceedings).
2. The application for leave to appeal was heard on 10 December 2025. Following the hearing, the Court made orders, among other things, dismissing the application with reasons to follow. These are the reasons for making those orders.

1. As at 2 July 2024, GBAG were applicants in six of ten proceedings in this Court arising out of the collapse of the Greensill group of companies in March 2021 (the GBAG Proceedings). Marsh were not parties to those six proceedings, although they were identified in defences in those proceedings as concurrent wrongdoers. Marsh Limited was and is a respondent in three of the proceedings, which were brought by Credit Suisse (CS) claiming damages and compensation from Marsh Limited for misleading or deceptive conduct and in negligence (CS Proceedings). Developments in the proceedings (collectively, the Greensill Proceedings) caused GBAG to consider that it needed to join Marsh Limited to the GBAG Proceedings.
2. On 2 July 2024, GBAG gave notice to Marsh that it intended to terminate a "Standstill Deed" and, thereafter, to join Marsh Limited to the GBAG Proceedings after the required 30-day notice period expired on 1 August 2024.
3. On 29 July 2024, Marsh commenced the English Proceedings and sought, relevantly, an interim and final anti-suit injunction restraining GBAG from commencing proceedings against Marsh in Australia and to prevent it joining Marsh to existing Australian proceedings. Marsh contended that GBAG was contractually bound by governing law and exclusive jurisdiction clauses (EJCs) contained in certain "letters of engagement" by which Marsh Limited agreed to provide insurance brokerage services. The EJCs in the letters of engagement were materially in the following form:

The Engagement and any non-contractual obligations arising out of or in connection with it shall be governed by and construed in accordance with English law and any disputes related thereto shall be subject to the exclusive jurisdiction of the English courts.

1. The English Court granted Marsh Limited an interim anti-suit injunction up until an inter-partes hearing could be held. Marsh Pty Ltd was unsuccessful in obtaining any continuing interim relief: PJ [5].
2. On 3 October 2024, GBAG filed an interlocutory application in this Court seeking anti-anti-suit relief against Marsh on the ground that Marsh had used documents, and information derived from documents produced by GBAG by way of discovery in the CS Proceedings in breach of the implied undertaking in Harman v Secretary of State for the Home Department [1983] 1 AC 280 and Hearne v Street (2008) 235 CLR 125; [2008] HCA 36 at [96], albeit described by Hayne, Heydon and Crennan JJ at [102] as "an obligation of law arising from circumstances in which the material was generated and received". On 11 October 2024, this Court granted an ex-parte interim anti-anti-suit injunction against Marsh Pty Ltd but not Marsh Limited: Credit Suisse Virtuoso SICAV-SIF v Insurance Australia Limited [2024] FCA 1193; PJ [34].
3. On 5 November 2024, pursuant to leave granted on 4 November 2024, GBAG joined Marsh Pty Ltd to the GBAG Proceedings: PJ [37].
4. An inter-partes hearing was held in the English Proceedings on 20 and 21 November 2024. With a confined exception, the English Court declined to continue the interim anti-suit relief which Marsh Limited had been granted on an ex-parte basis. The English Court was not satisfied to the degree required that there was an exclusive jurisdiction agreement which bound GBAG: PJ [8].
5. On 14 March 2025, GBAG was granted leave to join Marsh Limited to the GBAG Proceedings. GBAG's claims in the GBAG Proceedings include statutory claims that Marsh engaged in misleading or deceptive conduct (MDC) by making representations about the validity of certain insurance policies that were issued to GBAG and about the authority of the managing agent who entered into those policies on behalf of the insurer: PJ [49].
6. On 11 April 2025, Marsh Limited was granted leave to amend its pleading in England to include a claim for a mandatory injunction requiring GBAG to stay the GBAG Proceedings against Marsh Limited, and alternatively a claim for damages for breach of the letters of engagement: PJ [50], [55], [58]. The English Court made orders for the trial of the English Proceedings, with a view to judgment being delivered before the trial of the GBAG Proceedings in August 2026: PJ [58]. The English Proceedings were subsequently fixed for hearing from 27 April 2026 to 6 May 2026: PJ [58]. Orders were also made in the English Proceedings for disclosure and exchange of witness statements. On 16 April 2025, Marsh Limited served its amended claim form and amended particulars in the English Proceedings: PJ [58].
7. On 24 April 2025, GBAG filed an interlocutory application for anti-anti-suit relief against Marsh in this Court. This application was heard ex-parte by Moshinsky J, who made orders that Marsh Limited be restrained from taking steps in England to interfere with the interlocutory application until it could be determined at an inter-partes hearing. His Honour delivered concise ex-tempore reasons, explaining that the orders were to preserve the status quo until an inter-partes hearing: PJ [59].
8. The interlocutory application filed 24 April 2025 was amended on 12 June 2025 and is the subject of the primary judge's judgment and order: PJ [60].
9. The position now is that Marsh Limited has also been joined to the six GBAG Proceedings to which Marsh Pty Ltd was earlier joined. GBAG has also commenced a separate proceeding against Marsh Limited and Marsh Pty Ltd such that there are now seven GBAG Proceedings and eleven Greensill Proceedings: PJ [10].
10. If Marsh obtained final anti-suit relief against GBAG in the English Proceedings, that would prevent GBAG from pursuing its claims against Marsh in the seven GBAG Proceedings: PJ [11].
11. As the primary judge observed at PJ [12], it is in these circumstances that GBAG applied before the primary judge for anti-anti-suit relief against Marsh. The issue the primary judge determined was whether the Court should restrain Marsh from continuing the English Proceedings or commencing new proceedings in respect of the subject matter of the GBAG Proceedings. That injunction would operate until the final determination of the claims made against Marsh in the seven GBAG Proceedings, including the claim for final injunctive relief. If granted, the existing anti-anti-suit injunction against Marsh Pty Ltd which was made in a different Greensill Proceeding would be superfluous and should be dissolved: PJ [12].

1. On any application to appeal from interlocutory orders, an applicant must demonstrate error in the orders under challenge, not merely the reasons for decision: Australian Broadcasting Corporation v Chau Chak Wing (2019) 271 FCR 632; [2019] FCAFC 125 at [3]. An applicant must further establish (a) that the decision in question is attended with sufficient doubt to warrant the grant of leave; and (b) that substantial injustice will result from a refusal of leave to appeal: Décor Corporation Pty Ltd v Dart Industries Inc (1991) 33 FCR 397 at 398-399. Those considerations are cumulative and bear upon each other: Bellamy's Australia v Basil (2019) 372 ALR 638; [2019] FCAFC 147 at [7]. That is, the degree of doubt which will be sufficient is informed by the relevant injustice.

1. Marsh, in their draft notice of appeal, raise four proposed grounds of appeal:

(1) The primary judge erred in exercising the Court's implied jurisdiction to grant an anti-anti-suit injunction against Marsh.

(2) The primary judge erred in exercising the Court's equitable jurisdiction to grant an anti-anti-suit injunction against Marsh.

(3) The primary judge erred in failing to refuse an anti-anti-suit injunction against Marsh on the basis of comity.

(4) The primary judge erred in finding that the balance of convenience favoured the grant of anti-anti-suit injunctive relief.

1. Marsh contended that the principles governing the exercise of the Court's inherent or implied jurisdiction to grant anti-anti-suit relief were stated by the High Court in CSR Ltd v Cigna Insurance Australia Ltd (1997) 189 CLR 345 at 391-392. The majority in the High Court held that the power to grant an anti-suit injunction, which springs from the court's inherent power to protect the "integrity" of its own processes, is to be exercised "when the administration of justice so demands or...when necessary for the protection of the court's own proceedings or processes". Anti-anti-suit relief may be necessary to protect the integrity of the Court's processes where a party has commenced foreign proceedings which "interfere with or have a tendency to interfere with" proceedings in the domestic court: CSR at 392. Those principles are not disputed by GBAG. It is the primary judge's application of those principles that is in issue.
2. The primary judge held at PJ [94] that the English Proceedings "have the tendency to interfere with the determination of the claims regularly brought against Marsh in the GBAG Proceedings" and that this was "sufficient for the exercise of the implied jurisdiction" to grant anti-anti-suit relief. That conclusion was based on the primary judge's findings at PJ [86]-[88] that, if anti-suit relief were granted in the English Proceedings, it would interfere with the GBAG Proceedings by preventing GBAG from continuing those proceedings. Marsh contended that in making those findings, his Honour erred in the following respects.
3. First, Marsh submitted that the primary judge wrongly held at PJ [88] and [94] that the prospect of Marsh obtaining anti-suit relief in the English Proceedings was sufficient to constitute interference with this Court's processes and procedures, in circumstances where the sole purpose of the injunctive relief sought in England was to enforce the EJCs in the letters of engagement. Marsh submitted that nothing in CSR provides authority for that approach or suggests that the High Court intended that result. Moreover, Marsh submitted that it would facilitate the subversion of EJCs generally.
4. Secondly, Marsh submitted that the primary judge should have held that the English Proceedings could not interfere with this Court's processes unless the statutory prohibitions against MDC upon which GBAG relies in the GBAG Proceedings (MDC Provisions) are mandatory laws of the forum. Marsh submitted that in circumstances where the preservation of its MDC claims in Australia was the primary basis on which GBAG sought anti-anti-suit relief, the primary judge erred in granting that relief without deciding whether the MDC Provisions are mandatory laws of the Australian forum: PJ [94]-[95]. Marsh submitted that the primary judge made no such finding, and such a finding would be contrary to principle and authority and should not be made by the Full Court.
5. Finally, Marsh submitted that they could only succeed in obtaining a final anti-suit injunction in the English Proceedings if the English Court finds that GBAG is bound by the EJCs in the letters of engagement. It contended that granting anti-anti-suit relief in such circumstances is functionally equivalent to saying that GBAG must be permitted to bring its MDC claims, which form no part of the law of England and Wales, in this proceeding notwithstanding the governing law component of the EJCs. Marsh submitted that that can only be so if the MDC Provisions are mandatory laws of the Australian forum. However, the primary judge at PJ [94]-[95] found that the exercise of the Court's implied jurisdiction to grant anti-anti-suit relief in this case "does not depend on a conclusion that the statutory misleading conduct provisions are mandatory laws of Australia" and that it was "neither necessary nor appropriate to decide for the purposes of this application whether the statutory misleading conduct provisions are 'mandatory' laws of the forum". Those conclusions of the primary judge, Marsh contends, were erroneous.
6. Thirdly, Marsh submitted that the primary judge should have found that the English Proceedings did not interfere with the GBAG Proceedings in circumstances where, at the time that Marsh commenced the English Proceedings, it had not been joined to the GBAG Proceedings in Australia.
7. Fourthly, Marsh submitted that the primary judge misapplied the test in CSR by failing to identify any reason why granting anti-anti-suit relief was necessary to protect the integrity of the Court's own proceedings or processes or why the administration of justice required such relief be granted.
8. Finally, Marsh submitted that in this case, the primary judge should have held that, in circumstances where Marsh had brought the English Proceedings in order to enforce the EJCs in the letters of engagement and prior to Marsh's joinder to the GBAG Proceedings, the English Proceedings did not undermine this Court's processes or procedures and did not deliver any form of collateral advantage to Marsh in the GBAG Proceedings, such that anti-anti-suit relief was not necessary to protect the integrity of the Court's own proceedings or processes.

1. We detect no error in the path of reasoning of the primary judge at PJ [94] where his Honour held that that the English Proceedings "have the tendency to interfere with the determination of the claims regularly brought against Marsh in the GBAG Proceedings" and that this was "sufficient for the exercise of the implied jurisdiction" to grant anti-anti-suit relief. As will be seen below, Marsh's submission that the primary judge erred proceeds on their narrow view of the "circumstances" and "purpose" of the English Proceedings. Once the primary judge's findings as to the circumstances and purpose of the English Proceedings is understood, the weakness in Marsh's submission is exposed.
2. It is convenient to begin with Marsh's first and third submissions.
3. Contrary to those submissions, the circumstances in which the primary judge considered the implied jurisdiction to grant anti-anti-suit relief were not simply, as Marsh put it, that Marsh had brought the English Proceedings prior to Marsh's joinder to the GBAG Proceedings and in order for Marsh to enforce the EJCs in the letters of engagement.
4. The primary judge's findings as to the circumstances were set out at PJ [81]-[87].
5. Relevantly, on 2 July 2024, GBAG gave Marsh notice that it intended to terminate the Standstill Deed and join Marsh Limited to the GBAG Proceedings after the required 30-day notice period expired. Marsh commenced the English Proceedings on 29 July 2024, shortly before the 30-day notice period expired: PJ [81]-[82].
6. Further, Marsh Pty Ltd was wholly unsuccessful in obtaining anti-suit relief and Marsh Limited was largely unsuccessful in obtaining inter partes anti-suit relief in the English Proceedings: PJ [84]. This requires some elaboration. The English Court declined to grant Marsh Limited an interim anti-suit injunction, with a confined exception, because it was not satisfied to the degree required that there was an exclusive jurisdiction agreement which bound GBAG: PJ [8]. There was no dispute that Marsh had to meet a high standard to obtain anti-suit relief, that is, the English Court had to be satisfied that there was a high degree of probability that there was a binding jurisdiction clause: Marsh Limited & Anor v Greensill Bank & Anor [2024] EWHC 3068 (Marsh v Greensill (ASI)) at [46] (Deputy Judge Simon Kolton KC). The English Court was not satisfied to the required degree. Indeed, Deputy Judge Simon Kolton KC stated, at [81]:

For these reasons, I cannot conclude to a high degree of probability that Marsh will (or would) succeed on the question of authority at trial. On the contrary, I consider Marsh would be more likely than not to fail to make good its case at trial.

1. The one instance where Marsh Limited was successful in obtaining anti-suit relief related to the letter of engagement between Marsh Limited and GBAG dated 18 April 2018. Marsh was wholly unsuccessful in relation to the Greensill Capital (UK) Ltd (in administration) (GCUK) letters of engagement dated 3 March 2017, 27 March 2018, 27 March 2019 and 1 March 2020: PJ [42]. Marsh had argued that the GCUK letters of engagement were binding on GBAG on the basis of actual or apparent (ostensible) authority, alternatively on the grounds of ratification, which the English Court rejected: Marsh v Greensill (ASI) at [73], [77] and [80].
2. After Marsh largely failed to obtain inter partes anti-suit relief in the English Proceedings, Marsh Pty Ltd was joined to the first six GBAG Proceedings on 5 November 2024 and Marsh Limited was joined to the first six GBAG Proceedings on 17 March 2025. GBAG commenced the seventh GBAG Proceeding against Marsh on 12 March 2025: PJ [85].
3. As the primary judge stated, at PJ [86], on each of those occasions, the Court's jurisdiction with respect to Marsh was regularly invoked because there was no relevant anti-suit injunction which prevented the commencement of the proceeding against Marsh or the joinder of the relevant Marsh entity to the relevant proceeding.
4. Contrary to Marsh's submission, the primary judge did not accept that Marsh's sole purpose of seeking injunctive relief in the English Proceedings was to enforce the EJCs. His Honour found that, at the time GBAG gave notice of its intention to terminate the Standstill Deed, Marsh Pty Ltd considered it was likely that GBAG would seek to join it to the GBAG Proceedings. In addition to Marsh Limited being a respondent in the CS Proceedings, Marsh had been told (at least by 26 July 2024) that GBAG would adopt Insurance Australia Ltd's "concurrent wrongdoers" defence in the GBAG Proceedings which had named both Marsh Limited and Marsh Pty Ltd: PJ [23]. As his Honour observed, the relevant statutory proportionate liability regimes operate such that, where a concurrent wrongdoer defence is raised, naming a person who is not an existing respondent, it is for the applicant to join the asserted concurrent wrongdoer if it wishes to protect itself from the possibility of under‑recovery for any losses established: PJ [23].
5. The primary judge found that Marsh's purpose of commencing the English Proceedings was to prevent GBAG from pursuing future claims against Marsh. His Honour found, at PJ [83], that:

The English Proceedings were commenced because Marsh knew that Marsh was likely to be joined by GBAG to the first six GBAG Proceedings and wished to prevent that occurring by obtaining anti‑suit relief. Marsh Ltd was already a respondent in the CS Proceedings in which claims for damages were brought against it for negligence and misleading or deceptive conduct. Further, the concurrent wrongdoer defences raised by IAL, BCC and Mr Brereton in the first six GBAG Proceedings identified Marsh as concurrent wrongdoers. This defence (if successful) would operate to reduce any judgment against IAL, BCC and Mr Brereton which could be given in favour of GBAG by reference to the proportionate responsibility of (amongst others) Marsh. It was almost inevitable that GBAG would seek to join Marsh in those circumstances. This was a reason why Marsh sought the relief it did from the English Court: CB240 at [138].

1. The primary judge's findings at PJ [23] and [83] were not challenged.
2. It was in those circumstances that the primary judge found, correctly, that if final anti-suit relief is granted in the English Proceedings to prevent GBAG from continuing the existing proceedings so far as they concern Marsh, that relief will interfere with the GBAG Proceedings: PJ [86]. Furthermore, that Marsh's newly amended claim in the English Proceedings for a mandatory injunction to require GBAG to apply to stay the GBAG Proceedings, if granted, would also interfere with GBAG's Proceedings in this Court: PJ [87].
3. On that basis, the primary judge concluded, at PJ [88], that the English Proceedings have a tendency to interfere with proceedings in this Court and, accordingly, there is a basis for the Court to exercise its implied jurisdiction to protect proceedings regularly before it, by granting anti‑anti‑suit relief.
4. The primary judge then proceeded to consider whether the Court should grant such relief. His Honour noted Marsh's submissions that the relief which Marsh seeks in the English Proceedings would only be granted if GBAG was a party to the GCUK letters of engagement and, relatedly, that the injunctive relief Marsh sought would not be granted if GBAG establishes that there are "strong reasons" for not enforcing the EJCs: PJ [91]-[92].
5. Addressing those submissions, the primary judge found, at PJ [94], that:

It is sufficient for the exercise of the implied jurisdiction that the English Proceedings have the tendency to interfere with the determination of the claims regularly brought against Marsh in the GBAG Proceedings. The exercise of jurisdiction on this basis does not depend on a conclusion that the statutory misleading conduct provisions are mandatory laws of Australia.

1. The primary judge had found that the English Proceedings had been brought to prevent GBAG from bringing future claims against Marsh in the GBAG Proceedings and in new proceedings. Moreover, this Court is the only forum in which the MDC claims have been raised. The anti-anti-suit relief was in the interests of the administration of justice and necessary to protect the proceedings and processes in this Court because, in the absence of that relief, Marsh intended to pursue final anti-suit relief in the English Proceedings, which would prevent the Court from determining the claims against Marsh in the GBAG Proceedings, including the MDC claims.
2. For those reasons, the primary judge was correct to find that the English Proceedings "have the tendency to interfere with the determination of the claims regularly brought against Marsh in the GBAG Proceedings" and that this was "sufficient for the exercise of the implied jurisdiction" to grant anti-anti-suit relief. Marsh's first and third submissions are rejected.
3. This takes us to Marsh's second submission. Marsh submitted that in circumstances where the preservation of its MDC claims in Australia was the primary basis on which GBAG sought anti-anti-suit relief, the primary judge erred in granting that relief without deciding whether the MDC Provisions are mandatory laws of the forum: PJ [94]-[95].
4. As the primary judge in effect observed, at PJ [95], the question as to whether the MDC Provisions are mandatory laws of the forum is not settled. As his Honour also observed, at PJ [96], it was undesirable to determine whether the MDC Provisions are mandatory laws on the basis of incomplete facts. In our assessment, there was no error in his Honour deciding that it was neither necessary nor appropriate to decide the mandatory law question in the context of an interlocutory application on incomplete facts. Marsh's second submission is rejected.
5. Finally, as to Marsh's fourth submission, although his Honour did not expressly say so, the anti-anti-suit relief was necessary for the protection of this Court's own proceedings or processes, or the administration of justice, because Marsh's purpose in bringing the English Proceedings was to prevent the claims proceeding in this Court having been told that GBAG was about to join Marsh Limited to the GBAG Proceedings. The final anti-suit relief, or mandatory injunction requiring GBAG to seek a stay of the GBAG Proceedings, which Marsh sought in the English Proceedings, if granted, would prevent this Court from determining the claims brought against Marsh in the GBAG Proceedings, including the MDC claims. The primary judge's reasons properly read identified those matters as the reason why the anti-anti-suit relief was necessary to protect the integrity of the Court's own proceedings or processes and why the administration of justice required such relief to be granted. Marsh's fourth submission is similarly rejected.
6. Proposed ground one is untenable.

1. The principles governing the circumstances in which the Court may exercise its equitable jurisdiction to grant anti-anti-suit relief are uncontroversial and were relevantly set out by the primary judge at PJ [102]-[120]. An anti-anti-suit injunction may be granted when foreign proceedings are, according to the principles of equity, "vexatious or oppressive": CSR at 393. Proceedings are vexatious or oppressive if brought "for the dominant purpose of preventing another party from pursuing remedies available in another court" (PJ [115]), or if complete relief is available in the Australian proceeding, then it may be vexatious to commence proceedings in a foreign jurisdiction: PJ [116]-[117].
2. Marsh submitted that something more than the mere co-existence of proceedings in different countries is required - "there must be a 'complete correspondence' between the proceedings and it must be shown that the prosecution of the foreign proceeding would be 'productive of serious and unjustified trouble and harassment' or 'severely and unfairly burdensome, prejudicial or damaging'", citing CSR at 393, 395 and 401. We consider these are separate, not conjunctive, requirements having regard to CSR at 393-394 and 400-401.
3. The primary judge found, at PJ [135], that the English Proceedings were vexatious or oppressive, such as to enliven the Court's equitable jurisdiction to grant anti-anti-suit relief. Marsh submitted that the primary judge reached that conclusion on two separate bases.
4. The first basis was that the English Proceedings were "instituted, amended and are being continued for the purpose of preventing GBAG from making statutory misleading conduct claims and having those claims determined": PJ [135]. Marsh submitted that, having accepted that Marsh's purpose in bringing the English Proceedings was to enforce the EJCs, at PJ [123] and [125], the primary judge should have found that this was insufficient to make the English Proceedings vexatious or oppressive, particularly in circumstances where his Honour appeared to accept that Marsh had an arguable basis for the relief sought in the English Proceedings: PJ [127].
5. The second basis on which the primary judge found that the English Proceedings were vexatious or oppressive was that complete relief is only available in the GBAG Proceedings: PJ [128] and [135]. Marsh submitted that the flaw in that conclusion is that the English Proceedings are the only forum in which Marsh can enforce an EJC in favour of England and obtain final injunctive relief restraining GBAG from prosecuting the GBAG Proceedings in breach of the Letters of Engagement. The primary judge should accordingly have held that complete relief is not available in the GBAG Proceedings and that not all of the issues arising in the English Proceedings may be raised and determined in the GBAG Proceedings.

1. In considering the exercise of the Court's equitable jurisdiction in relation to vexatious or oppressive proceedings, the primary judge made even clearer findings in relation to Marsh's purpose in instituting, amending and continuing the English Proceedings, which Marsh overlooked.
2. First, the primary judge found, at PJ [122], that the English Proceedings were commenced for the purpose of preventing GBAG from making future claims against Marsh in the existing GBAG Proceedings and in new proceedings.
3. It was in that context that the primary judge noted, at PJ [123], that Marsh characterises its purpose "as one of seeking to enforce choice of law and jurisdiction clauses in contracts signed by GCUK which it asserts are contractually binding on GBAG". His Honour observed, however, that expressing Marsh's purpose in that way "does not detract from the fact that the purpose of the commencement of the English Proceedings was to prevent future claims being made against Marsh in the existing GBAG Proceedings and in new proceedings": PJ [123].
4. Secondly, the primary judge found, at PJ [124], that:

The purpose of Marsh's amendment to the Claim Form in April 2025, in particular to require GBAG to stay the GBAG Proceedings - made after the APF Proceeding was commenced and after Marsh had been joined to the other six GBAG Proceedings - is one of seeking to disrupt this Court from determining then existing claims regularly brought by GBAG.

1. Marsh did not challenge the primary judge's findings at PJ [122] and [124].
2. Relevantly, the primary judge found that Marsh commenced the English Proceedings for the purpose of preventing GBAG from making future claims against Marsh in the existing GBAG Proceedings and in new proceedings, and that Marsh amended its claim in the English Proceedings in April 2025, to seek a mandatory injunction which would require GBAG to seek a stay of the GBAG Proceedings, in order to disrupt this Court from determining then existing claims regularly brought by GBAG.
3. Those findings were a sufficient basis for the primary judge to find that the English Proceedings were vexatious or oppressive.
4. The primary judge found, at PJ [128] and [135], that complete relief is only available in the GBAG Proceedings. Marsh submitted that the English Proceedings are the only forum in which Marsh can enforce the EJC in favour of England and obtain final injunctive relief restraining GBAG from prosecuting the GBAG Proceedings in breach of the letters of engagement.
5. As the primary judge observed, at PJ [130], where an anti‑anti‑suit injunction is sought, it can always be said that the respondent's claim for injunctive (anti‑suit) relief does not arise for determination in the Court considering whether to grant anti‑anti‑suit relief. The relevant focus, however, must be on whether there is anything to be gained by the foreign proceedings over and above what may be gained in the domestic proceedings: CSR at 393. This directs attention to whether the underlying facts and issues arise for determination in both proceedings. The EJC claims arise for determination in the GBAG and English Proceedings, although the relief that might be granted as a result of the determination of the EJC claims would differ, whereas this Court is the only forum in which the MDC claims are raised and can be determined. Accordingly, his Honour was correct to find that complete relief, in the sense of the determination of all the claims raised by the parties, is only available in the GBAG Proceedings.
6. Proposed ground two is untenable.

1. The power to grant injunctions in restraint of foreign proceedings "should be exercised with caution", whether the injunction is sought in the exercise of the court's implied or equitable jurisdiction: CSR at 396. Considerations of comity require that only in an exceptional case should a domestic court restrain a person from exercising a right given by a foreign law to invoke the jurisdiction of a foreign court: Allstate Life Insurance Co v Australia and New Zealand Banking Group Ltd (No 1) (1996) 64 FCR 1 at 25, and anti-anti-suit injunction should be granted with particular caution.
2. Marsh submitted that the primary judge held at PJ [157] that principles of comity did not require anti-anti-suit relief to be refused, reasoning that: (a) there was no anti-suit injunction in the English Proceedings that would be negated by an anti-anti-suit injunction in Australia; and (b) an anti-suit injunction to restrain foreign proceedings "will always interfere with the processes of the foreign court because the domestic injunction restrains the party from further prosecuting the proceedings in the foreign court": PJ [156]. Marsh submitted that the effect of this reasoning is that considerations of comity will be unpersuasive to prevent a court from issuing anti-anti-suit relief unless it would cut across an existing anti-suit injunction in foreign proceedings, which Marsh submitted is plainly wrong. Marsh submitted that this error by the primary judge caused the exercise of the discretion to miscarry, in that it failed to afford proper weight to the following considerations of comity, all of which, Marsh submitted, weighs heavily against anti-anti-suit relief.
3. First, Marsh regularly invoked the English Court's jurisdiction to determine its claims for relief based on the EJCs, which is governed by, and is to be construed in accordance with English law.
4. Secondly, Marsh submitted that it commenced the English Proceedings on 29 July 2024, prior to Marsh's joinder to the GBAG Proceedings in Australia and prior to GBAG's first application for anti-anti-suit relief before Moshinsky J in October 2024.
5. Thirdly, Marsh submitted that GBAG has never challenged the English Court's jurisdiction to hear Marsh's claims in the English Proceedings or sought to stay those proceedings. GBAG elected instead to submit to the English Court's jurisdiction and to defend Marsh's claims in England. For more than a year, Marsh submitted, GBAG has been defending Marsh's claims on the basis that the English Court is the appropriate forum for determining the existence and effect of the EJCs.
6. Fourthly, Marsh submitted the English Court made comprehensive orders for the preparation of the English Proceedings for trial including the provision of disclosure and exchange of evidence, to which GBAG consented, which were progressing, and which the granting of an anti-anti-suit injunction would require Marsh to breach or ask the English Court to vacate.
7. Fifthly, Marsh submitted that the English Proceedings are listed for trial in April 2026, prior to the hearing of the GBAG Proceedings, to which GBAG consented.
8. Finally, Marsh submitted that at the trial of the English Proceedings, the English Court will determine, in light of all of the evidence to be led at the hearing, whether GBAG is entitled to prosecute the GBAG Proceedings against Marsh in Australia.
9. Marsh submitted that for these reasons, the primary judge should have held that comity alone provided a sufficient basis to refuse to grant an anti-anti-suit injunction. Marsh submitted that the primary judge misapplied the principles of comity so as to constitute a House v The King error (House v The King (1936) 55 CLR 499; [1936] HCA 40). Marsh submitted that the complaint is not simply one of weight as the respondents contend, rather, the court's reasoning erroneously operated to focus on whether the principles of comity required relief to be refused (PJ [157]). Marsh submitted the proper question is not whether comity precludes relief but whether this case is sufficiently exceptional that relief should flow notwithstanding comity principles.
10. Marsh submitted that the principles of comity are inherently discretionary and cannot sensibly be divorced from other issues relevant to the grant of an anti-anti-suit relief as the primary judge purported to do at PJ [80], [121] and [136].

1. We detect no error in the path of reasoning of the primary judge at PJ [144]-[159] where his Honour held that principles of comity do not require the relief to be refused in the circumstances of this case.
2. The six matters which Marsh identify as not being afforded proper weight by the primary judge when considering principles of comity do not demonstrate any House v The King error. The primary judge, having considered and weighed each of the matters relied upon by Marsh, recognised that the anti-anti-suit injunction would interfere with the English Proceedings, but that interference was the natural consequence of such an order being made: PJ [56]. The primary judge correctly recognised that comity requires proper respect for the processes of the foreign court and a considered response in the particular circumstances of each case. If the English Proceedings were to continue, and if Marsh were successful, the English Court's order against GBAG would interfere with the processes of this Court. The primary judge was correct to so find. It follows that proposed ground three is untenable and must be rejected.

1. Marsh submitted that the primary judge, in finding that the balance of convenience supported granting anti-anti-suit relief (PJ [177]), erred in the following three respects.
2. The first error, Marsh submitted, was the primary judge's finding at PJ [169(b)] that Marsh can "raise the choice of law and exclusive jurisdiction clauses in the GBAG Proceedings". Marsh submitted that that conclusion was wrong because the English Proceedings are the only forum in which Marsh can enforce the EJCs in favour of England and its claim for injunctive relief in the English Proceedings is not available in Australia.
3. The second error, Marsh submitted, was the primary judge's findings at PJ [172]-[174] that the usual undertaking proffered by GBAG was of substance. Marsh submitted that it was common ground that GBAG has been in insolvency administration since March 2021. In addition, Marsh submitted that: (a) there was no evidence to support the proposition in PJ [174] that "appropriate steps are likely to be able to be devised to ensure that any amount which Marsh is ordered to pay [to GBAG] is appropriately quarantined until its claim for damages is determined in the English Proceedings", and GBAG did not identify or undertake to implement any precise or certain means by which that outcome might be achieved; and (b) Marsh led uncontested evidence that its costs of litigating the GBAG Proceedings would likely be in the range of $15 million to $20 million and that any damages claim arising from GBAG's breaches of the EJCs could run into billions of dollars: PJ [170]-[172]. In those circumstances, Marsh submitted that the primary judge should have found that the usual undertaking had no substance and that this was a factor weighing strongly against granting anti-anti-suit relief.
4. The third error, Marsh submitted, was the primary judge's failure to take into account or to afford proper weight to the fact that: (a) granting anti-anti-suit relief would foreclose Marsh's claim for injunctive relief in the English Proceedings and prevent Marsh from enforcing the EJCs; and (b) GBAG's inability to bring MDC claims in England was a matter to which the English Court would have regard in determining the English Proceedings. Those factors, Marsh submitted, in combination with the other matters in relation to the usual undertakings to damages, were sufficient to tip the balance of convenience firmly against granting anti-anti-suit relief, and the primary judge should have so found.

1. The primary judge's reasons demonstrate that there was no error in the approach which the primary judge took at PJ [160]-[177] to weighing the factors relevant to balance of convenience and do not disclose any appealable error. The primary judge's reasoning was quintessentially evaluative and gave rise to no House v The King error.
2. The primary judge was correct to find at PJ [169(b)] that Marsh can raise the choice of law and exclusive jurisdiction clauses in the GBAG Proceedings. Marsh, in its defences filed in the GBAG Proceedings, has expressly reserved their rights and did not waive them, in relation to the enforcement and application of the exclusive jurisdiction clause, and positively rely upon the limitation of liability provisions, which will inevitably require them to show that GBAG was bound by letters of engagement: AB, Part A, Tab 4, 273 and 292; Defence at [203AF(c)] and [229]-[231].
3. As to the second asserted error, there was evidence before the primary judge that GBAG had provided substantial security to the respondents in the GBAG Proceedings. There was also evidence that GBAG would provide security in the sum of $5 million by way of payment to the court with liberty to apply for further security. GBAG had indicated at the hearing before the primary judge through its senior counsel, that it "would consent to an order, at the time of judgment, that that money be paid into court effectively and be...'quarantined' - so as to be available if there were a claw-back": Michelle Fox Affidavit dated 27 August 2025 at [12] and [13], and T148.28-30; see also T144.15-20.
4. As to the third asserted error, that the primary judge failed to take into account or afford proper weight to the fact that (a) granting anti-anti-suit relief would foreclose Marsh's claim for injunctive relief in the English Proceedings and prevent Marsh from enforcing its EJCs; and (b) GBAG's inability to bring MDC claims in England was a matter to which the English Court would have regard in determining the English Proceedings, the primary judge was aware of those factors and weighed them at PJ [164] and [169(b)].
5. The primary judge's reasons demonstrate no appealable error in the manner in which his Honour weighed the competing considerations in determining that the balance of convenience favoured the grant of the relief sought by GBAG. Proposed ground four is untenable.

1. Leave to appeal will be refused. The applicant will pay the respondent's costs of the application.

I certify that the preceding eighty-five (85) numbered paragraphs are a true copy of the Reasons for Judgment of the Honourable Justices Bromwich, Anderson and Neskovcin.