This book explores law-making in international affairs and is compiled to celebrate the 50th birthday of Professor Jan Klabbers, a leading international law and international relations scholar, who has made a significant contribution to the understanding of the sources of international obligations and the idea of constitutionalism in international law. Inspired by Professor Klabbers' wide-ranging interests in international law, his determined disregard for disciplinary boundaries and his often provocative views, the book looks at law-making in a colourful variety of different ways and occasionally seeks to push the envelope in terms of what it means to think and write about law and its making.