AbstractThe jurisdictional reach of causes of action brought under the Alien Tort Statute 17891 (ATS) was considered by the Supreme Court of the United States in Kiobel v Royal Dutch Petroleum.2 The claimants in this decision sought to bring an action before a US District Court asserting universal civil jurisdiction over the conduct of foreign corporations performed against non-US nationals in the territory of a foreign State. Although the Supreme Court dismissed the particular claim on the basis of a domestic canon of statutory interpretation (the presumption against extraterritoriality), the narrowness of its reasoning left open the possibility for actions to continue being brought under the ATS which assert universal civil jurisdiction over the harm caused by individuals rather than corporations. Moreover, this position was specifically endorsed by a four-member minority of the Supreme Court in the Concurring Opinion of Justice Breyer. This paper argues that the reasoning of Justice Breyer is unconvincing and goes on to suggest that assertions of civil jurisdiction made under the universal principle are unlawful in international law as they fail to find a legal basis in either customary or conventional international law.