The principles of collective security recently came into stark relief in the forcible mission to ‘protect civilians’ in Libya. While NATO did the dirty work this was, after all, an operation authorized by the United Nations Security Council (UNSC), the organ of the UN bestowed with ‘primary responsibility for the maintenance of international peace and security’ (Article 24(1), UN Charter (1945)). In fact, in contrast to its misadventures in Kosovo in 1999, the NATO hierarchy was this time firm in its conviction that before any action of a forcible nature was to be taken the authorization of the UNSC should be obtained. While this change in stance was to be commended, it also did not prevent the controversy that ensued over the interpretation of the mandate provided, in particular the lengths to which the acting states of NATO could go in ‘protecting civilians’. Collective Security primarily sets out to address such issues of ‘competence allocation’ between two, occasionally competing, collective security organizations.

Once the term ‘collective security’ is mentioned it is tempting to think only of enforcement actions involving the use of force. However, as Orakhelashvili deftly highlights throughout the book, it is about far more than this and in many respects has its most interesting elements in those stages outside of or preceding such enforcement action. While there is a voluminous literature in the fields of international law and international relations on issues of collective security there is not, as the author points out, a ‘comprehensive study of collective security that covers all the pertinent institutions and arrangements’ (p 1). Consequently, the interplay between the different institutions' activities and assertions and the allocation of competence between them is an underlying theme of the book.

After providing an introduction to the essence and definition of the subject matter of the title of the book in Chapter 1, Orakhelashvili proceeds to provide in Chapter 2 a comprehensive account of the collective security institutions under focus. While much focus is placed upon the UN, and in particular the UNSC, the aim of providing a comprehensive study manifests itself in the range and diversity of regional security organizations included. Chapter 3 provides what could be seen as the methodological chapter of the book as it discusses the mechanics of the regime of competence allocation which underpins the rest of the book and, in doing so, ably explores the underlying principles of complementarity and subsidiarity. This chapter precedes and, in doing so, sets up nicely the discussion in Chapter 4 on the identification of a threat to the peace. While one may query why the other triggers of a breach of the peace and act of aggression are not provided the same attention as threats, given not only the greater difficulty in identifying the latter but also their prevalent identification in resolutions of the UNSC, a dedicated chapter seems appropriate. Competence allocation also features heavily in Chapter 5 on the various possible responses open upon the identification of such a threat, such as sanctions, territorial administration, the authorization of the use of force, and enforcement action by regional organizations. The interface between unilateral and multilateral action is at its greatest in the interrelation between self-defence and collective security and is the subject matter of Chapter 6 while the proliferation of peacekeeping operations—and their contribution to the maintenance of international peace and security—means that they are provided extensive focus in Chapter 7. Given that one of the book's central themes is that the neither the UNSC nor any other collective security body is above the law the legal consequences of illegal collective security acts and decisions is well covered in Chapter 8, the final chapter of the book.

Overall, the extent of research is impressive and the intricacy of detail that Orakhelashvili engages with is truly commendable which means that the aim of providing comprehensive coverage of the area is generally both achieved and original in doing so. It is, however, in this detail where on occasion questions marks can be raised over both the assertions made and the conclusions reached. For example, a determination of the existence of a threat to the peace under Article 39 of the UN Charter by the UNSC is the main trigger for the various mechanisms of enforcement at its disposal. However, the author seems to interpret the phrasing of this provision—that the Council ‘shall’ determine the existence of a threat—to mean that it is somehow under a legal obligation to do so. True, the UNSC is indeed under an obligation to make such a determination as a precondition to turning to the enforcement mechanisms of Chapter VII. But the author goes further and makes the claim there is an independent obligation to declare the existence of such a threat so that if it does not do so when one objectively exists it is in violation of international law. Yet while the UNSC may fail to meet its responsibilities in such circumstances, this is different to saying that it has somehow violated a legal obligation. Indeed, while such a determination was made in the context of Libya, one was not—due to the threat or use of the veto by some of the UNSC's permanent members—made in the context of Syria, despite one, for all intents and purposes, objectively existing. The UNSC as an institution failed in this instance, but was not a lawbreaker. Indeed, the use of the veto by the permanent members on this occasion may be accused as being illegitimate or politically motivated, but this does not alter the fact that the veto is a fundamental part of the UN collective security system that was created in 1945, regardless of whether others agree with its use on a particular occasion.

Similarly, Orakhelashvili takes the view that only conduct which is not in compliance with international law can constitute a threat to the peace. Indeed, the author states that ‘[t]he Charter cannot be reasonably interpreted as requiring states, under Articles 1 and 2, to comply with international law and then admitting, under Article 39, the possibility of the Security Council's finding a threat to the peace in the conduct of a state that has complied with international law.’ (p 150) But it is, on the contrary, totally possible that, for example, the passage of a vessel through particular waters can at the same time constitute lawful behaviour and a threat to the peace due to the potential aggravation it might cause to another state.

The book is also provocative and perhaps lacks nuance in places with, for example, its talk of ‘the NATO armed attack against Yugoslavia’ in 1999 (p 222 (emphasis added)). While the use of this term here remains unqualified, one cannot help but draw the inference that Orakhelashvili is making the claim that NATO member states were guilty of an act of aggression which gave rise to a right of self-defence by Yugoslavia. While many will undoubtedly agree with this legal categorization of this particular use of force, many will also see these events of 1999 in the bigger picture of putting an end to the humanitarian crisis that was occurring at the time and should not, therefore, be framed in common parlance simply as an ‘armed attack’. It also assesses things very much from a state-centric view. This is reflected in Orakhelashvili's insistence on the point that self-defence is only available against armed attacks by states, not non-state actors (pp 277–8). Many still hold to this view, including perhaps notably the International Court of Justice which at least has appeared to take a restrictive view on the issue. Nonetheless, given the post-9/11 state practice—which has accepted that the use of force in self-defence is now possible against such actors, if not also against their host state—the adoption of such a categorical position on this issue is perhaps unwise.

Some notable omissions are also identifiable. There is, for example, no extensive discussion on the current proposals and need for reform of the UNSC to make more effective the current arrangements for collective security. The book would also have benefited from having some appendices with reference made to at least the key parts of the constitutional documents of the various collective security organizations referred to. At the very least it would have been useful to have the full text of Chapters VI and VII of the UN Charter included at some point within the book. Yet, these relatively minor points of criticism should not detract from the fact that there is much more to admire in this book which must be acknowledged as a tour de force on the subject of collective security. The book is provocative and thought-provoking yet the most comprehensive of any in its coverage. The distinctive and original approach adopted by Orakhelashvili will be sure to make it the leading text in the field. The book is also both academic yet instructive in nature thereby opening it up to a broad readership to include not only academics, researchers and students but also practitioners and civil servants.