For hundreds of years, the writ of habeas corpus has allowed detainees to seek a judicial ruling on the lawfulness of their detention. The Constitution's Suspension Clause explicitly preserves that right. Despite that long history, the Military Commissions Act of 2006 deprives federal courts of jurisdiction to hear habeas petitions filed by detainees at Guantánamo. The lower court in this case upheld that provision on the theory that the Constitution, including the Suspension Clause, does not apply at Guantánamo. The ACLU challenges that conclusion in its amicus brief on multiple grounds. In particular, we argue that American officials acting outside the United States are bound to obey the Constitution unless it would be "impracticable and anomalous" to do so, a standard that various Supreme Court Justices have recognized over the past half-century.