Sources: Customary International Law

Sources: Customary International Law

Learn how state obligations emerge without states formally offering consent.


This lesson examines customary international law. In it, we’ll consider customary law’s status as a source of international law, how it develops, and its status in relation to other sources.

I.               Source of Law

International law draws on four sources. They’re treaties, customary law, principles of law found across legal systems, and the writings of international legal scholars and jurists. Customary law is among...