The Supreme Court’s use of international and foreign law has garnered substantial commentary in recent years, but almost all of that commentary has focused on two constitutional cases: Lawrence v. Texas1 and Roper v. Simmons. This article attempts to put the Court’s reliance on international law in those cases within the broader context of the Court’s use of such material in other cases. Since the twenty-fi rst century the Court has occasionally looked abroad to interpret the Constitution, federal statutes, treaties, and federal common law. Such reliance is rare and typically uncontroversial. But in a few instances the Court’s reliance on international law has been highly contentious, particularly when it appears that the Court is usurping or unduly limiting the authority of the executive branch or expanding the role of the judicial branch...