This book analyses the authority to detain American citizens who are suspected of being members, agents, or associates of Al Qaeda, the Taliban and possibly other terrorist organisations as enemy combatants. The Department of Justice cites two World War II era cases, Ex parte Quirin and In re Territo, to support its contention that the President may order that certain U.S. citizens as well as non-citizens be held as enemy combatants pursuant to the law of war and Article II of the Constitution. Critics, however, question the assertion of executive authority to detain U.S. citizens, without ordinary due process of law, in order to prevent terrorist acts or gather intelligence; and some argue that Congress has prohibited such detention of U.S. citizens when it enacted 18 U.S.C. 4001. While the Fourth Circuit Court of Appeals has agreed with the Bush Administration that Congress authorised such detentions in its authorisation for the President to use force against those he determines are responsible for the September 11, 2001, attacks on the United States, the Second Circuit recently held that Congress has not authorised such detentions.