Alien Enemies Act

The Alien Enemies Act of 1798 is a wartime federal law that allows the president, during a declared war or an invasion or predatory incursion by a foreign nation, to detain or deport citizens of the hostile nation who are present in the United States. Before 2025 it had been invoked only three times, during the War of 1812 and the two World Wars. In March 2025, Donald Trump invoked it through a proclamation targeting the Venezuelan gang Tren de Aragua, and the administration used it to fly alleged members to El Salvador.