The system of detention and military trial authorized by President George W. Bush on November 13, 2001, and additional claimed authority to hold terrorist suspects indefinitely without process, have been litigated in several judicial circuits, moving from district courts to the Supreme Court and back down again. In 2006, these authorities returned to the Court for further exploration in Hamdan v. Rumsfeld. Regrettably, until very recently the separation of powers issues raised by the President’s initiatives received little attention from Congress, which, under the Constitution, has primary responsibility over military courts, tribunals “inferior to the supreme Court,” “Offenses against the Law of Nations,” the war power, and “Rules concerning Captures on Land and Water.” Because of congressional passivity, the principal checks on presidential power have been supplied instead by litigants and courts. The constitutional issues that emerge from this concentration of power in the presidency form the central theme of this article.