Customary International Law Law and Legal Definition

Customary international law refers to those aspects of international law that becomes binding on nations through general acceptance as a matter of legal obligation. Those principles of law that states began to adopt as a custom are the main sources of customary international law. In the opinion of International Court of Justice, jurists, the U.N. and its member states customary international law is the primary source of international law. Laws of war as envisaged in the Geneva Convention is an example of customary international law.

In the Restatement of the Law, Third, Foreign Relations Law of the United States, customary international law is defined as international law that results from a general and consistent practice of states followed by them from a sense of legal obligation.