International Law as a Tool of Constitutional Interpretation in the Early Immigration Power Cases

Abstract

The Supreme Court has recently caused controversy by citing international legal authorities in decisions that interpret the United States Constitution. Many commentators have claimed that this is a new development, but they overlook a significant precedent.

International law played an important role in the late-nineteenth-century cases in which the Supreme Court established the federal power to regulate immigration. Those cases looked to something very similar to what we now call "customary international law" as support for its interpretation of Constitution. Reliance on international law in constitutional cases may be a good idea or a bad idea, but it is not a new one.

Keywords: international law, immigration, constitution, customary international law, history, supreme court