The Kiobel case raises intertwined questions of statutory interpretation, federal common law, and international law. The Alien Tort Statute (ATS) authorizes courts to create federal common law causes of action, but only for conduct that violates well-established contemporary norms of international law. Moreover, some extraterritorial applications of the statute arguably violate international law. The Court’s decision may also influence the ongoing development of the customary international law of both human rights and prescriptive jurisdiction...because the decision could count as “state practice” – one component of custom. And the government has not made the Court’s task any easier; its supplemental brief says little about international law, and was not joined by the State Department. This post explains the appropriate relationship between federal common law and international law in ATS cases, and analyzes corporate liability and the extraterritorial application of the statute.