The means of making international law are increasingly differentiated. The book contains the proceedings of a conference hosted by the Max Planck Institute for Comparative Public Law and International Law that brought together academics, practitioners and judges from Africa, America, Asia and Europe. Developments of International Law in Treaty Making explores the various means of making non-conventional/non-treaty law and the cross-cutting issues that they raise. Law-making by technical/informal expert bodies, Conferences of Parties, international organizations, the UN Security Council, regional organizations and arrangements and non-state actors is examined in turn. This forms the basis for the analysis of the complementarity of international treaty law, customary international law and non-traditional law-making, potential subject matters of non-treaty law-making, domestic consequences of non-treaty law-making, proliferation of actors, commissions and treaty bodies of the UN system, and International courts and tribunals.