5 Customary International Law

Subject(s):

Customary international law — Foreign judgments, recognition and enforcement — Peremptory norms / ius cogens — Interpretation of judgments

This chapter considers the status in the U.S. legal system of customary international law. After considering what the text of the Constitution suggests about this issue, the chapter discusses how courts historically applied customary international law in cases in which it was relevant and how courts referred to it as “part of our law.” The chapter also explores the possibility that customary international law might have the status of modern “federal common law” and what such a status might mean for questions of jurisdiction, preemption of state law, and limitations on congressional and executive authority. It also discusses ways in which customary international law can be applied indirectly in the U.S. legal system, such as through application of the Charming Betsy canon of construction. The chapter concludes by discussing recent debates over the Supreme Court’s consideration of foreign and international law materials when interpreting the U.S. Constitution.