This article examines the judicial use of foreign jurisprudence in human rights adjudication, using as data a set of court decisions regarding the death penalty from over a dozen different tribunals in different parts of the world. The global human rights norms and judicial discourse on human rights in these cases can be understood and explained by comparing the contemporary practices to the medieval ius commune. The modern ius commune of human rights has three distinct characteristics which it shares with the historical example to which it is analogized: it is broadly transnational in scope and application; it is grounded in certain universal principles that are assumed to have have cross-cultural and supra-positive validity (in the case of human rights, the idea of human dignity); and it neither trumps local law nor is necessarily subordinate to it, but rather exists in a symbiotic relationship with it. The article concludes with a suggestion to reexamine the way in which the United States Supreme Court has begun to engage foreign jurisprudence, as a consequence of this understanding of the new ius commune of human rights.