Sources of International Law: Treaties, Custom, and Legal Principles
International law examines the recognized legal sources through which rules arise, acquire authority, and are interpreted within the international system. Because there is no single global legislature, international law develops through treaties, customary international law, general principles of law, judicial decisions, scholarly writings, and the evolving practice of states and international institutions. This article explores how Article 38 of the Statute of the International Court of Justice became the classical framework for identifying those sources, while also examining the dynamic interaction between treaty law, custom, legal principles, soft law, and peremptory norms in the development of international legal order. By clarifying how international law is made, argued, and applied, the article provides a foundation for understanding sovereignty, human rights, armed conflict, maritime governance, dispute settlement, and the wider structure of global legal authority.









