Since 1923, the Hague Academy of International Law has promoted the study of private and public international law through courses and lectures delivered by leading scholars on topics of contemporary interest. The permanent record of this teaching has appeared in the Collected Courses of the Academy, and more recently in the form of an online database. Since 2008, however, selected courses have been published in an accessible pocketbook format, at a price that must make the books one of the better bargains in the increasingly expensive world of legal publishing. The Academy and its publishers are to be commended on this enterprise, which it is hoped will be extended so as to introduce a new audience to the work of Kahn-Freund, Lipstein, Mann and von Mehren, among other distinguished private international law experts on the Hague Conference roll call.

Professor McLachlan's work is the first English language pocketbook in the field of private international law and is based on the author's 2008 lectures (published in Recueil des Cours, Vol 336). Its subject, the treatment of parallel proceedings in international litigation before national courts, arbitration and international tribunals, has grown exponentially in visibility and importance in the past decade. It is at the heart of the current debates concerning revision of the Brussels I Regulation (Reg (EC) No 44/2001), with both the general impact of prior proceedings in another Member State and the treatment of proceedings brought in the face of putative choice of court and arbitration agreements being closely scrutinized. The publication is, therefore, timely.

The commentary is divided into five parts. The first introduces the subject and its guiding principles. The second gives an account of the techniques for dealing with conflicting or overlapping proceedings before national courts. The third examines parallel proceedings involving arbitration tribunals, with a focus on investment treaty arbitration. The fourth addresses the subject in its application to situations involving the growing number of tribunals established by international treaties. The final part draws together the discussion and suggests possible ways of oiling the wheels of international litigation to resolve ‘conflicts of litigation’ in the future.

The pocketbook format has the feel of a travel guide, and both experienced and new visitors to the subject will find this work informative and thought provoking. It combines an historical account of the development of lis pendens rules with a survey of the current landscape and more detailed accounts of its key features. The first two chapters will be of particular interest to private international lawyers, and should be required reading for those engaged in the Brussels I Review. Professor McLachlan addresses the reasons for the growing phenomenon of inter-jurisdictional conflict and techniques for controlling this. He traces the historical development of ‘lis pendens rules’ via the Dutch glossators of the 17^th century, and the practice of the English Court of Chancery and the Scots Court of Session in the 19th Century, to the first seised rules of the Brussels I regime and the modern doctrine of forum non conveniens. His meticulous research discloses (pp 94–102) that the rules now found in articles 27 and 28 of the Brussels I Regulation align themselves with the pre-Regulation practice of the original Brussels Convention States not in the field of international litigation, but instead in the field of intra-national jurisdictional conflicts. Thus, articles 21 and 22 of the 1968 Brussels Convention provide an early manifestation of the now overpowering desire to treat the Member States of what is now the European Union as a single judicial area.

In the following chapters, addressing parallel proceedings in the context of arbitration and international dispute resolution, Professor McLachlan acknowledges that the features of the landscape are less developed. Against this background, his analysis draws upon a conviction that unifying conceptions of ‘international arbitration’ and public international law can be understood as requiring a coherent, non-fragmented approach to dispute resolution within, and in relations between, these domains. For example, he suggests (pp 346–362, 406–407) that lis pendens—taken, here, to refer to ‘the avoidance of duplicative litigation’—should be seen a general principle of public international law, although not one requiring a particular judicial technique for conflict avoidance. In view of the limited data available, those who do not share the author's view of the systemic nature of these areas of law may be less inclined to agree with his conclusions, or may doubt the utility of a general principle of this kind.

In the final chapter, Professor McLachlan draws together the different strands of his discussion, focusing once again on dispute resolution before domestic courts. He is critical of both the European (Brussels I Regulation, articles 27–30) and common law (discretionary stays of proceedings and anti-suit injunctions) models, and argues for a more sophisticated solution along the lines of that proposed by the International Law Association's Leuven/London Principles on Declining and Referring Jurisdiction in Civil and Commercial Litigation ((2000) 69 ILA Rep Conf 13, 138).

The author's status as rapporteur to the Committee whose work led to the adoption of these Principles makes him a powerful advocate for their adoption as a new model for addressing the problems arising from parallel international litigation. In supporting better communication and coordination between courts and tribunals seised of related disputes (see, in particular, Principle 5.2), the work of the Committee can be seen as being ahead of its time, anticipating the approach of later European legislative instruments (see, eg, Council Framework Decision 2009/948/JHA on prevention and settlement of conflicts of exercise of jurisdiction in criminal proceedings, OJ L328/42 [15.12.2009]) and recommendations for reform of the EU lis pendens rules in the Commission's Green Paper on the Brussels I Regulation (COM (2009) 175 final [21.4.2009], pp 5–8). Judicial initiatives to avoid parallel litigation and conflicting judgments in cross-border cases are also becoming increasingly common, particularly in the fields of insolvency and family law (see, for example, the judgment of Henderson J in Perpetual Trustee Company Limited v BNY Corporate Trustee Services Limited [2009] EWHC 2953 (Ch.) and the comments of Thorpe LJ in Golubovich v Golubovich [2010] EWCA Civ 810, at [96]).

In an age when trade and commerce have transcended differences of geography, language and culture, and recognizing that recent economic difficulties have placed an increasing strain upon public finances, there can be no turning back from this bipartisan approach to cross-border litigation. In the present writer's view, however, the overall approach of the London/Leuven Principles remains problematic, in that the core provisions controlling the power to decline jurisdiction (Principle 4) appear to combine the least attractive features of the European and common law models: that is to say (a) the incentive to race to court in order to gain a judicial advantage accorded to the court first seised, with (b) the uncertainty and expense (as well as the possible tendency towards a ‘homing instinct’) of a discretionary approach to resolving the problems resulting from potential duplication of litigation. Although the Principles require the court first seised to decline jurisdiction where it is satisfied that another court is a ‘manifestly more appropriate forum’, the legal and evidential burden which that test imposes on the party challenging jurisdiction, coupled with the broad, discretionary nature of the enquiry (Principle 4.3) and the unfamiliarity of legal systems outside the common law world with an exercise of this kind, may be thought likely to foster among disputing parties an approach of ‘sue first, argue later’ in the hope that their decision to start proceedings will prove decisive in the jurisdictional battle.

If an international solution is to be achieved to this intractable problem, the chosen rule of priority should (so far as possible) be both predictable and neutral in terms of the conduct of the parties during the litigation, thereby promoting settlement rather than tactical or abusive manoeuvering. As presently drafted, the London/Leuven Principles appear unlikely to achieve this latter objective. A possible refinement, in the present writer's view, would be to seek to develop a hierarchy of jurisdictional criteria (with, for example, jurisdiction based on a choice of court agreement outranking jurisdiction of the domicile of the party claimed to be liable and both outranking other connecting factors), combining this with (a) a priority period triggered by service of the first set of proceedings enabling an application to be made or a decision taken by a court of its own motion to refer the matter to a court whose jurisdiction (if established) would have a higher ranking, (b) more limited use of the first seised rule or an alternative tie-break mechanism in cases where the jurisdictional hierarchy does not resolve the question of priority, and (c) a limited override mechanism available only if a court is satisfied that justice cannot be achieved in the forum having priority. Of course, a proposal of this kind simply begs a second, equally complex and, perhaps, insoluble set of questions as to where particular bases of jurisdiction should lie in the hierarchy and how, precisely, the priority system should operate.

As Professor McLachlan would acknowledge, the science of the conflict of litigation is a young one and the debate has a long way do run. In the meantime, his work admirably lays the foundations for future development of the area and will be indispensible to scholars and practitioners grappling with the difficult issues that it raises.