I. Treaties and Individual Rights   105 II. The Treaty Power and American Federalism   107 III. Delegations of Authority to International Institutions   109 IV. Domestic Application of Customary International Law   113 In his informative and timely book, Justice Breyer repeatedly emphasizes that the Supreme Court is a domestic court, not an international tribunal, and that there is no Supreme Court for the world. Against that backdrop, Justice Breyer suggests various functions that the Supreme Court can perform as it faces an increasingly international docket, such as promoting harmonization, fostering collaboration, and helping to promote the rule of law. I do not disagree that the Supreme Court can play these roles in appropriate cases, but in this essay I want to emphasize another important role that the Supreme Court