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GW Law Library
Research Guides

International Law Research Resources

A research guide to selected sources in public international law available at the Burns Law Library.


Customary international law is particularly important as a source of international law in absence of a treaty or other controlling rule. J. L. Brierly, in The Law of Nations: an Introduction to the International Law of Peace states that in order to determine what international customary law is on a particular subject "we must look at what states do in their relations with one another and attempt to understand why they do it, and in particular whether they recognize an obligation to adopt a certain course, or, in the words of Article 38, we must examine whether the alleged custom shows ‘a general practice accepted as law."

Ian Brownlie, in Principles of Public International Law lists the following sources of custom as "diplomatic correspondence, policy statements, press releases, the opinions of official legal advisers, official manuals on legal questions, e.g. manuals of military law, executive decisions and practices, orders to naval forces etc., comments by governments on drafts produced by the International Law Commission, state legislation, international and national judicial decisions, recitals in treaties in the same form, the practice of international organs, and resolutions relating to legal questions in the United Nations General Assembly."


Selected Treatises on Customary International Law

Selected International Law Yearbooks

Sources for U.S. Practice in International Law

U.S. Diplomatic Correspondence