This brief argues that the Military Commission Act, which purports to withdraw the jurisdiction of federal courts over certain habeas corpus petitions, is unconstitutional. By way of background, the Bush administration has argued that if it decides to house prisoners in facilities that are not on U.S. soil, such as the prison at Guantanamo Bay, Cuba, federal courts will lack jurisdiction to consider claims of wrongful imprisonment. This brief urges the Supreme Court to reject that argument. The habeas writ cannot be abrogated in the absence of a "rebellion" or "invasion." Since Congress has not invoked either of those exceptions to the general rule, the Military Commission Act is unconstitutional insofar as it attempts to revoke federal court jurisdiction over petitions for writs of habeas corpus.