This introductory chapter provides an overview of the growing interest in international law in the Asia and Pacific regions, which has been driven by threats as well as opportunities. On the threat side are transnational challenges such as climate change, environmental harms, forced displacement, persistent poverty, human rights violations and international crimes, and terrorism. Meanwhile, opportunities include economic integration, human development, and the proliferation of specialized branches of law as well as dispute settlement mechanisms and institutions. No book has so far covered how Asian and Pacific states as a whole participate in each of the main specialized branches of international law; individually contribute to the making and application of international law on the international plane; and individually implement international law in their national legal systems. This book aims to fill these significant gaps in professional and scholarly knowledge.