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Ryan M. Scoville, Finding Customary International Law, 101 Iowa L. Rev. 1893 (2016)

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101 Iowa Law Review 1893 (2016)


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 this task. Conducting a citation analysis of opinions published since the U.S. Supreme Court’s 2004 decision in Sosa v. Alvarez-Machain, this Article analyzes 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.

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