Providing a clear and comprehensive overview of the world's most significant and complex international organization is no easy feat; however, Oppenheim's International Law: United Nations Volumes I and II accomplishes exactly that. The publication is divided into two volumes, four parts, and thirty-one chapters, and serves as an authoritative commentary on the United Nations (UN). It provides a brief history of the organization, its organs, and specialized agencies, and serves as a practice guide regarding the procedures for admission to membership, powers, financing, substantive responsibilities, and adjudication within the UN system.

The impressive amount of research and scholarship reflected in the commentary is a testament to its team of authors, which consists of preeminent adjudicators and scholars in the field of international law. The team is helmed by Judge Rosalyn Higgins, who previously served as the president of the International Court of Justice and who was also its first female judge. The other authors include: Philippa Webb, associate professor at King's College London; Dapo Akande, professor of public international law at the University of Oxford; Sandesh Sivakumaran, professor of public international law at the University of Nottingham; and James Sloan, professor of international law at the University of Glasgow School of Law.

The publication is easy to navigate and will be useful to a variety of audiences, including UN officials, legal practitioners, scholars and academics, and others whose work requires them to understand the workings of the UN. It is replete with helpful jurisprudential references that assist the reader in understanding the internal functioning of the UN and its bodies. The publication also strikes an appropriate balance between being succinct while also providing sufficient detail and linking to resources for those looking for additional materials regarding a specific issue. Its tables of cases, instruments, and UN documents also serve as helpful guides and make it easier to navigate the treatise. For example, readers seeking an in-depth understanding of the Security Council's voting structure will find not only the UN Charter rules and Security Council procedures but also informal practices that have come to shape the Council's operation. Footnotes provide links to the negotiating history and interventions made by various delegations, providing additional context for these rules and practices.

As set forth in the introduction, the purpose of the publication is to provide “a study of UN legal practice, ‘warts and all’” (Vol. I, p. 3, para. 1.03). To this end, although the authors’ primary aim is to provide an overview and summary of the key topics related to the UN, the publication does not shy away from highlighting weaknesses and inconsistencies in the UN's legal practice and evolution as it sought to address some of these issues. Further, although the personal commentary by the authors is sparse, it is included in some instances to invite debate and discussion amongst readers. The publication also provides a fair amount of historical background for the topics it covers in order to provide the reader with necessary context.

Several chapters are of particular note. Chapter 3, covering the UN Security Council, provides a helpful overview of the UN's most influential organ. The chapter covers the Security Council's membership, rules of procedure, types of Security Council meetings, participation in the Security Council, voting procedures, and the Security Council's functions. The section on Security Council meeting formats is particularly well-written, covering the many different ways in which Security Council members meet in formal and informal capacities.

Particularly topical is the section addressing membership in the Council in light of the ongoing debate, particularly by developing states, to include new permanent seats for underrepresented regions, including states in Africa. This section summarizes the evolution of the debate from when the issue was first introduced to the UN agenda in 1979 to more recent statements made by permanent member states in favor of reform. This topic will continue to be relevant in the years to come in light of the continuing challenge the UN faces in attempting to resolve increasingly complex international security issues, which will make the role of the Security Council and representation in it even more important.

Chapter 3 is also interspersed with historical background and examples that provide important context and display some of the complexities arising out of the workings of the Security Council. For example, in reviewing the Security Council's voting procedures, the authors discuss British Prime Minister Tony Blair's announcement in 2002 that if a draft resolution authorizing the use of force in Iraq were to be “unreasonably” vetoed by another permanent member, the United Kingdom would be authorized to nonetheless use force even without a specific resolution to that effect (Vol. I, p. 89, para. 3.62). The example invites debate regarding the questions of whether a Security Council veto could ever be considered “unreasonable,” and whether a member state would have the authority to circumvent the Security Council in that circumstance (the publication concludes that it would not).

Chapter 12, covering the UN and international law, is also extremely clear despite the dense nature of its subject matter. It is divided into five subtopics addressing the UN's role in the development, interpretation, and application of international law, as well as the organization's obligation to comply with international law and the effect of the UN Charter on international law. These section are interesting in light of the current debate surrounding the legality of Security Council permanent members vetoing resolutions aimed at preventing war crimes or other atrocities that violate peremptory norms. Indeed, in stating that “at a minimum, the Security Council may not violate jus cogens norms,”Footnote ¹ the publication invites discussion of whether use of the veto power could ever run afoul of this principle, and if so, what solutions should be proposed to curtail such violations (Vol. I, pp. 421–22, para. 12.19). Chapter 12 also provides a balanced overview of the divergent views surrounding the scope of Article 103 and the supremacy of UN Charter obligations over other international agreements and the consequences of a conflict between an act and the UN Charter. The chapter also highlights the UN's role in developing human rights and its peacekeeping efforts, despite the limited references to human rights in the UN Charter.

Another important chapter of particular relevance for legal practitioners is Chapter 25, which discusses the UN's promotion of international law. The chapter is divided into ten subparts, covering a number of topics, including the Sixth Committee of the General Assembly (GA), the UN Commission on International Trade Law (UNCITRAL), the GA's work related to the law of the sea, and the UN's promotion of treaties, although the majority of the chapter is dedicated to a discussion of the International Law Commission (ILC). The focus on the ILC allows for an in-depth summary and analysis of the ILC's working methods, functions, and relationship to other UN bodies. For example, in covering the appointment of the ILC's special rapporteurs, the chapter provides extensive commentary regarding the length of their appointments and content of their work.

The chapter also provides an interesting overview of the development of the ILC's work, reviewing how the ILC's focus has shifted from the production of draft articles to the development of non-binding instruments. While the majority of the chapter, like the rest of the publication, is focused on providing a succinct summary and analysis, the authors also take the opportunity to provide their own commentary in a few significant instances. For example, in discussing the election of ILC members, the authors point to the dearth of female ILC members “given the number of capable female international lawyers” (Vol. II, p. 931, para. 25.10). This observation engages the reader and invites debate about the work of the ILC, the UN in general, and potential areas for improvement in the future, including the need for member states to promote qualified female candidates.

The overview of UNCITRAL, as well as the General Assembly's work on the law of the sea, is brief and receives less attention than the ILC. Even though the chapter still manages to cover the general key points for both topics, it omits a discussion of some of the key UNCITRAL-related developments in recent years. While the chapter briefly mentions the success of UNCITRAL in the area of international arbitration, it does not note of the ongoing work of UNCITRAL Working Group III with respect to the possible reform of investor-state dispute settlement. The chapter also does not mention the developments leading up to UNCITRAL’s recent ratification of the final draft of the Singapore Convention, which will make it easier for parties to enforce mediated settlement agreements across jurisdictions and will serve to make mediation a more attractive form of dispute resolution.Footnote ²

The publication's detailed overview of the International Court of Justice (ICJ) in Chapter 29 is appropriate given the ICJ's significance as the principal judicial body of the UN. The chapter covers a number of topics that will be of interest to legal practitioners, including nominations and election to the bench, the court's functions and jurisdiction, and its internal practices and evidentiary rules. The publication's use of jurisprudence to illustrate its points is particularly effective in these sections, including in its discussion of judges ad hoc, and the court's function in issuing advisory opinions. Along with these practical issues, this chapter also covers a number of topics related to the court that perhaps do not receive as much attention in other works, including the ICJ's financing, its independence from other UN organs, and its relationship to other courts and tribunals that determine issues of international law.

The treatise provides a comprehensive analysis of the UN and its bodies that will no doubt be of great use to scholars and practitioners alike.