Following the publication of the third edition in 2017, the long-awaited fourth edition has now been published for students of international law and international relations. This edition includes Michelle Chase as a contributing author and has been updated to address significant developments since the previous edition, including Russia’s invasion of Ukraine since 2022 and the conflict between Israel and Palestine since 2023.

The book is organised into four sections. Part I, “Actors in International Law”, examines the roles of states, international organisations, non-governmental organisations, individuals, and international courts and tribunals in creating, implementing, and enforcing international law. Part II, “Structures and Processes of International Law”, employs case studies to illustrate that, while international law possesses a degree of autonomy from world politics, it remains fundamentally interconnected with world politics due to its inherent indeterminacy. Part III, “Issues in International Law”, analyses contemporary challenges in areas such as armed conflict (jus ad bellum and jus in bello), weapons of mass destruction, climate change, human rights, and crime, utilising recent case studies. In Part IV, “Conclusion”, the authors argue that current challenges to international law stem from geopolitical transformations, particularly the relative decline of US power and the rise of China and other states. They assert that, given the increasing importance of international cooperation via international law, it is crucial to critically evaluate ongoing changes both within and beyond the field of international law.

The authors belong to the tradition of a dynamic understanding of international law. As the authors positively highlight (pp. 135–8), this tradition encompasses the New Haven School as well as critical international legal studies such as Third World Approaches to International Law and feminist international law. What distinguishes the authors from these other scholars is their approach, which examines the dynamic nature of international law and its relationship with world politics while essentially remaining within the framework of legal positivism. Although it is not possible to cover everything within the limited scope of this review, the series of theoretical frameworks developed by the authors in Part II, including the three-level understanding of international law, the relationship between legal manoeuvring and political manoeuvring, and the “Multilateral Treaty Life Cycle” theory, enables a nuanced, dynamic, and realist understanding of international law. Whilst books discussing the relationship between international law and world politics often place greater emphasis on one or the other, this book strikes a perfect balance and is the ideal introductory textbook for students of both international law and international relations. At a time when concerns about the crisis in international law are growing, this is a book everyone interested in international law should read before succumbing to pessimism and abandoning it altogether.