This unique volume examines the opportunities for, and initiates work in, interdisciplinary research between the fields of international law and international relations; disciplines that have engaged little with one another since the Second World War. Written by leading experts in the fields of international law and international relations, it argues that such interdisciplinary research is central to the creation of a knowledge base among IR scholars and lawyers for the effective analysis and governance of macro and micro phenomena. International law is at the heart of international relations, but due to challenges of codification and enforceability, its apparent impact has been predominantly limited to commercial and civil arrangements. International lawyers have been saying for years that 'law matters' in international affairs and now current events are proving them right. International Law and International Relations makes a powerful contribution to the theory and practice of global security by initiating a research agenda, building an empirical base and offering a multidisciplinary approach that provides concrete answers to real-world problems of governance. This book will be of great interest to all students of international law, international relations and governance.