Finding Customary International Law

Abstract

Established doctrine holds that customary international law (CIL) arises from general and consistent state practice that is backed by a sense of legal obligation. Contemporary litigation requires federal courts to apply this doctrine to identify the contours of CIL in a diverse collection of cases ranging from civil actions under the Alien Tort Statute to criminal prosecutions under the Maritime Drug Law Enforcement Act. This Article provides an in-depth look at how federal judges carry out the task. Conducting a citation analysis of opinions published since the U.S. Supreme Court’s 2004 decision in Sosa v. Alvarez-Machain, the Article identifies the form, quality, and geographical origins of the authorities that tend to serve as evidence of custom; explores the implications of recent citation patterns; and offers ideas to help courts grapple more effectively with the challenge of finding custom.

Keywords: Customary International law, Federal Courts, Sosa, Alien Tort Statute, Citation Analysis