This book, a continuation of the series Select Proceedings of the European Society of International Law, contains the proceedings of the third biennial conference organized by the ESIL and the Max Planck Institute for Comparative Public Law and International Law in 2008. The conference was entitled 'International Law in a Heterogeneous World,' reflecting an idea which is central to the ESIL philosophy. Heterogeneity is considered one of the pillars upon which Europe's contribution to international law is built, and the subject was considered in a number of panels, including such diverse topics as migration, the history of international law, the rules on warfare, and international environmental law.