I argue that the Court’s nineteenth-century rulings in Ableman v. Booth and Tarble’s Case marked a little-known but sharp break with state courts’ decades-long practice of granting habeas relief to federal extrajudicial detainees. I contend that the Court’s reasoning in those cases is unpersuasive, and that modern efforts to rationalize those cases’ outcomes fare no better. I also argue that the Suspension Clause bars Congress from stripping state courts of their power to grant habeas relief to persons being extrajudicially detained by federal authorities.