“44 The judge summarised the relevant principles in paragraph 29 of his judgment by reference to Andrew Smith J's summary of them, which was approved by this court, in Royal Bank of Canada v Co-operatieve Centrale Raiffeissen-Boerenleenbank [2004] 1 CLC 170. They are set out in paragraph 8 of the judgment of Evans-Lombe J in this court: ‘(i) Under English law a person has no right to be sued in a particular forum, domestic or foreign, unless there is some specific factor that gives him that right, but a person may show such a right if he can invoke a contractual provision conferring it on him or if he can point to clearly unconscionable conduct (or the threat of unconscionable conduct) on the part of the party sought to be restrained: Turner v Grovit[2002] 1 WLR 107 at para 25 per Lord Hobhouse. (ii) There will be such unconscionable conduct if the pursuit of foreign proceedings is vexatious or oppressive or interferes with the due process of this Court: South Carolina Insurance Co v Assurantie Maatschappij de Zeven Provincien NV[1987] AC 24 at p 41D; Glencore International AG v Exter Shipping Ltd [2002] CLC 1090 at para 42. (iii) The fact that there are such concurrent proceedings does not in itself mean that the conduct of either action is vexatious or oppressive or an abuse of court, nor does that in itself justify the grant of an injunction: Société Nationale Industrielle Aerospatiale v Lee Kui Jak[1987] AC 817 at p 894C; Credit Suisse First Boston (Europe) Ltd v MLC (Bermuda) Ltd [1999]CLC 579 at p 596; Airbus Industrie GIE v Patel[1999] 1 AC 119 at p 133G–H. (iv) However, the court recognises the undesirable consequences that may result if concurrent actions in respect of the same subject matter proceed in two different countries: that “there may be conflicting judgments of the two courts concerned” or that there “may be an ugly rush to get one action decided ahead of the other in order to create a situation of res judicata or issue estoppel in the latter”: see The Abidin Daver[1984] AC 398 at pp 423H–424A per Lord Brandon. (v) The Court may conclude that a party is acting vexatiously or oppressively in pursuing foreign proceedings and that he should be ordered not to pursue them if (a) the English court is the natural forum for the trial of the dispute, and (b) justice does not require that the action should be allowed to proceed in the foreign court, and more specifically, that there is no advantage to the party sought to be restrained in pursuing the foreign proceedings of which he would be deprived and of which it would be unjust to deprive him: Société Aerospatiale, ibid at pp 895D and 896F— (vi) In exercising its jurisdiction to grant an injunction, “regard must be had to comity and so the jurisdiction is one which must be exercised with caution”: Airbus Industrie, ibid at p 708; 133F. Generally speaking in deciding whether or not to order that a party be restrained in the pursuit of foreign proceedings the court will be reluctant to take upon itself the decision whether a foreign forum is an inappropriate one: Turner v Grovit, ibid at para 25.’ 45 That seems to me to be a correct summary of the principles which have been developed to assist the court to decide how to decide whether to grant an anti-suit injunction to restrain foreign process in the exercise of the power conferred on the court under section [37] of the SCA 1981 to grant an injunction ‘in all cases in which it appears to the court to be just and convenient to do so. As the judge put it in paragraph 30 of his judgment, the essential touchstone is whether there has been unconscionable conduct or the threat of unconscionable conduct.”
“Leaving aside the provisions of the Brussels I Regulation and previous conventions, which are not relevant in this case, I would summarise the relevant key principles as follows. (1) Under English law the court may restrain a defendant over whom it has personal jurisdiction from instituting or continuing proceedings in a foreign court when it is necessary in the interests of justice to do. (2) It is too narrow to say that such an injunction may be granted only on grounds of vexation or oppression, but, where a matter is justiciable in an English and a foreign court, the party seeking an anti-suit injunction must generally show that proceeding before the foreign court is or would be vexatious or oppressive. (3) The courts have refrained from attempting a comprehensive definition of vexation or oppression, but in order to establish that proceeding in a foreign court is or would be vexatious or oppressive on grounds of forum non conveniens, it is generally necessary to show that (a) England is clearly the more appropriate forum (“the natural forum”), and (b) justice requires that the claimant in the foreign court should be restrained from proceeding there. (4) If the English court considers England to be the natural forum and can see no legitimate personal or juridical advantage in the claimant in the foreign proceedings being allowed to pursue them, it does not automatically follow that an anti-suit injunction should be granted. For that would be to overlook the important restraining influence of considerations of comity. (5) An anti-suit injunction always requires caution because by definition it involves interference with the process or potential process of a foreign court. An injunction to enforce an exclusive jurisdiction clause governed by English law is not regarded as a breach of comity, because it merely requires a party to honour his contract. In other cases, the principle of comity requires the court to recognise that, in deciding questions of weight to be attached to different factors, different judges operating under different legal systems with different legal policies may legitimately arrive at different answers, without occasioning a breach of customary international law or manifest injustice, and that in such circumstances it is not for an English court to arrogate to itself the decision how a foreign court should determine the matter. The stronger the connection of the foreign court with the parties and the subject matter of the dispute, the stronger the argument against intervention. (6) The prosecution of parallel proceedings in different jurisdictions is undesirable but not necessarily vexatious or oppressive. (7) A non-exclusive jurisdiction agreement precludes either party from later arguing that the forum identified is not an appropriate forum on grounds foreseeable at the time of the agreement, for the parties must be taken to have been aware of such matters at the time of the agreement. For that reason an application to stay on forum non conveniens grounds an action brought in England pursuant to an English non-exclusive jurisdiction clause will ordinarily fail unless the factors relied upon were unforeseeable at the time of the agreement. It does not follow that an alternative forum is necessarily inappropriate or inferior. (I will come to the question whether there is a presumption that parallel proceedings in an alternative jurisdiction are vexatious or oppressive). (8) The decision whether or not to grant an anti-suit injunction involves an exercise of discretion and the principles governing it contain an element of flexibility.”