Curtis Bradley, the William Van Alstyne Professor of Law and Professor of Public Policy Studies, has published Custom’s Future: International Law in a Changing World (Cambridge University Press, 2016), a collection of essays by leading international law experts that address the development of customary international law over time, the way it is applied by international and domestic tribunals, and the challenges that it faces going forward.

The book had its genesis in a yearlong school-wide project at Duke Law on custom and law that Bradley coordinated with Professor Mitu Gulati in the 2011-2012 academic year, which resulted in a symposium issue of the Duke Law Journal and other publications relating to customary international law. Bradley subsequently organized a conference in Geneva in 2012 as part of the Duke-Geneva Institute in Transnational Law on the role of opinio juris in customary international law, in which a number of the authors featured in his new collection participated.

Several members of the Duke Law faculty contributed essays to the collection. Bradley’s chapter contends that the application of customary international law by an international adjudicator “is best understood in terms similar to judicial development of the common law.” Gulati and co-author Stephen Choi offer an empirical examination of what international tribunals like the International Court of Justice cite in support of their rulings regarding customary international law. And Laurence Helfer, the Harry R. Chadwick, Sr. Professor of Law, with co-author Timothy Meyer, apply principal-agent theory to examine a shift by the U.N.’s International Law Commission in recent years away from codification efforts to “principles, conclusions, and draft articles that it does not recommend be turned into treaties.”

Sir Michael Wood, the special rapporteur for the International Law Commission’s project on customary international law, co-authored the final chapter on the continuing importance of this form of international law.