Over the dissents of conservative Justices Clarence Thomas and Samuel Alito, the emergency decision prevents authorities from removing the migrants under the Alien Enemies Act of 1798 as a legal challenge proceeds, a win for the American Civil Liberties Union (ACLU), which is suing on the migrants’ behalf.

But the justices declined the ACLU’s additional request to leapfrog the lower courts to immediately take up the issue of whether President Trump can invoke the rarely used law outside of wartime.