On the docket of the United States Supreme Court in 2004 is a substantial cluster of cases at the intersection of constitutional and international law. In the previous two Supreme Court Terms, the Court had adverted to sources of law and practice outside the United States, in its treatment of constitutional claims involving the death penalty and same-sex relationships. The apparent willingness of the Court to consider international and foreign authorities in reaching its conclusions on contested issues of constitutional law has raised to new promir nence the debate over the relationship between constitutional and international law. It is not yet clear whether the new (or newly rediscovered) interest of the Court in international sources presages a long-term trend toward a more cosmopolitan constitutional jurisprudence. On the assumption that this represents more than a passing fad, advocates before the Court in die current Term—for example, in the cases involving die “enemy combatant” detainees at Guantanamo Bay—have vigorously pressed arguments concerning international and foreign law in connection with the constitutional issues at stake. The Court's acceptance of quite a few cases raising a mixture of international and constitutional questions for decision in 2004 may signal that the Court is preparing for a new era of engagement with legal developments external to the United States, or, alternatively, that it seeks to limit (or in any event to delimit) the relevance of such developments for the U.S. legal system.