The Twilight of Customary International Law

96 Pages Posted: 8 Apr 2008 Last revised: 2 Nov 2008

See all articles by J. Patrick Kelly

J. Patrick Kelly

Widener University Delaware Law School


This article criticizes mainstream customary international legal theory as lacking authority and legitimacy. Few customary international law (CIL) norms are, in fact, customary. All customary law, international or otherwise, acquires its legitimacy from the normative belief of a community. Norms may be inferred from the repeated acts believed to be required using the inductive method. CIL, however, has become a device for judges, advocates, and self-interested states to deduce or create new norms without regard to the beliefs or participation of the vast majority of states and their people. CIL norms are constructed from non-binding resolutions and soft law instruments rather than widespread state practice or evident belief. In a diverse world of many different values, interests, and cultural histories valid CIL norms will be rare. The article suggests only more democratic consensual processes will produce effective norms in a decentralized international community without a consensus on values.

Keywords: international law, customary international law, international legal theory, custom, consent, international adjudication, international court of justice, legitimacy, persistent objector, global governance, international governance, judicial activism

JEL Classification: K33

Suggested Citation

Kelly, J. Patrick, The Twilight of Customary International Law. Virginia Journal of International Law, Vol. 40, No. 2, 2000, Available at SSRN:

J. Patrick Kelly (Contact Author)

Widener University Delaware Law School ( email )

4601 Concord Pike
Wilmington, DE 19803-0406
United States

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