Allan Buchanan is well known for his work on justice, secession, and self-determination. The volume under review draws on and builds upon his past work, developing and updating previously stated positions and setting new ground in formulating a moral approach to international law. The title of the book clearly encapsulates its content and the intentions of the author. Buchanan's first line in the book explains that it is “an attempt to develop moral foundations for international law” (p. 1). Undoubtedly this is a formidable and complex task, but one to which he skillfully addresses himself. His goal is to set out manageable frameworks for establishing and developing ideas and practices of justice and legitimacy that, in turn, will act as guiding principles in international law and relations. He certainly succeeds in achieving this and goes even further to set out interesting and provocative suggestions for reform of the international system. In short, this book is to be highly recommended, if not required, reading for anyone interested in the future of the international system.

The book is divided into four parts preceded by a synopsis and introduction. The introduction sets out Buchanan's views on why moral theorizing about international law is necessary and the main lines of argument to be pursued in the remainder of the work. The structure of the book then follows the title. Part I examines justice; it deals with issues of how and why we should be committed to a particular view of justice, the key role human rights plays in our understanding of minimal thresholds of justice, and the nature and place of distributive justice in the international system. Part II concerns legitimacy, with chapters building from a more general discussion of political legitimacy that is then applied to the issue of legitimacy in the recognition of states and the legitimacy of the international system as a whole. Part III covers self-determination, secession, and intrastate autonomy, demonstrating the application of the previous parts on justice and legitimacy. There is a considerable focus on self-determination and secession, not only because these are the author's main areas of research but also because secession and self-determination have become “one of the most important and perilous developments in international law in the last half-century” (pp. 1–2). Part IV sets out Buchanan's views on reform of the international legal system, based on the views of justice and legitimacy developed in the previous parts. The chapters within the parts are well connected and build upon each other to provide strong support for his main argument, which is relatively simple: We not only need to, but are also obligated, to work to develop institutional arrangements that protect basic human rights and improve upon existing ones in order to ensure that other individuals enjoy the benefits of rights protection, regardless of whether or not we have a direct link to or any interaction with these other persons.

In a review of this nature, it is not possible to give adequate coverage to Buchanan's thesis and to systematically deal with the arguments set out. Buchanan starts with the belief that in international law “there is a need for self-conscious, systematic moral reasoning” in order to derive “prescriptive principles that will provide substantial guidance” for international law to deal with the crucial issues it faces (p. 15). He rejects the belief that international law cannot or should not deal with moral prescriptions. He then builds his central theoretical concept, what he terms the “Natural Duty of Justice,” whereby all individuals have “a limited moral obligation to help ensure that all persons have access to institutions that protect their basic rights” (p. 27). It is based on Kantian ideas that every individual should be treated with equal worth and respect. The book goes on to demonstrate and justify why international law should direct itself to this simple but extremely multifaceted and contested idea. Buchanan avoids any sort of absolutism; he does reject aspects of traditional international law that fail to live up to the foundations of his moral theory, but in doing so, he deftly navigates through the system of law to give respect, where necessary, to existing international law, but at the same time showing how it may be reformed to be more in line with the Natural Duty of Justice.

What is perhaps one of the more valuable contributions of the work is the emphasis on the ability of international law to change and develop on the basis of moral prescriptions. In the concluding chapters, Buchanan details how change may occur in international law through a discussion on humanitarian intervention that is based on his moral theory. In doing so, he expresses the necessity of overriding existing rules of international law in order to live up to the Natural Duty of Justice. This will be controversial reading, but it will be up to the opponents of such a view to explain why international law should remain tied to ideas and practices that may bring stability to the system as a whole but result in harm to individuals.

The book is well written and structured, setting out the argument in an accessible manner. Buchanan takes us through his study in a systematic and organized fashion. There is continual reference to preceding and future sections in such a way that the reader never feels lost and can clearly see the links developing. Summaries of the argument are provided and key points highlighted throughout. In setting out his argument, he covers a good deal of ground, and he makes the effort to ensure that various criticisms or contrasting positions are dealt with head-on and not just glossed over. But this breadth may have been at the sacrifice of depth, as some points of the discussion come across as sketchy and thin. There is a noticeable lack of examples or elaborations in large parts of the book (Parts I and II) to illustrate the point being made. But in Part III, examples and illustrations are more forthcoming. A similar pattern follows in terms of referencing, with Part III providing citations to the wider literature and specific examples but the previous parts providing very little in this respect. If Buchanan wants to convince international lawyers of the need for change, his argument would be greatly enhanced by specific examples to demonstrate the points being made.

Justice, Legitimacy, and Self-Determination is to be highly recommended for all those interested in the current and future state of the international system. Whether or not one agrees with the general thrust or particular points of Buchanan's moral theory is irrelevant. The ideas put forth go to the heart of how the future of the international system will be shaped. Even if his suggestions are considered to be fanciful or even bizarre, it forces us to come up with our own prescription or to demonstrate that somehow international law is adequately addressing the needs of humanity. Recently, international law has been at the forefront of current events and has not fared all that well at times in demonstrating its relevance. It has become accepted that some sort of reform is necessary; Buchanan provides a convincing case for a particular direction for change that, it is to be hoped, will influence the future of the discipline.