United States law, in accordance with customary international law, has since 1798 permitted the internment or restriction of enemy aliens found within the United States during time of international conflict or war. The United States has applied this law in every declared war since the law’s enactment. Application of this law and related precedent to the present conflict (sometimes known as the Global War on Terror) permits the detention or restriction of aliens known or suspected of links to foreign terrorist organizations. In light of the United States’ ongoing debates over the detention of combatants in Guantanamo Bay—as well as the question whether to try them in military or civilian settings, if at all—this statute presents a secure alternative to the outright release of the detainees, or to their introduction into the civilian criminal justice system. Established law and precedent thereby affords a further option to address this thorny problem...