Elected last year on a promise to crack down on migrants, Trump invoked the 1798 Alien Enemies Act in an attempt to swiftly deport accused members of Tren de Aragua, a criminal gang originating from Venezuelan prisons that his administration labels a terrorist group.

High court acted in an emergency appeal from the American Civil Liberties Union contending that immigration authorities appeared to be moving to restart removals under the Alien Enemies Act of 1798.