The book "Developments of International Law in Treaty Making" offers a comprehensive analysis of the changing methods of creating international law. The content is based on the proceedings of a conference organized by the Max Planck Institute for Comparative Public Law and International Law. Experts, academics, and judges from various regions of the world, including Africa, America, Asia, and Europe, participated in the event. The work examines the different approaches to the creation of non-conventional or non-treaty law and highlights the associated challenges. Topics such as the role of technical and informal expert bodies, conferences of the parties, international organizations, and the impact of non-treaty law on national legal systems are discussed. This comprehensive examination enables a deeper understanding of the complementarity between international treaty law, customary international law, and non-traditional legal developments.