The Alien Enemies Act of 1798 gives the president wartime powers to deport undocumented immigrants with little to no due process.

In 1798, with the U.S. preparing for what it believed would be a war with France, Congress passed a series of laws that increased the federal government’s reach. The Alien Enemies Act was created to give the president wide powers to imprison and deport noncitizens in time of war.

US President Donald Trump invoked a little-known, centuries-old wartime power, the Alien Enemies Act, to send more than 200 alleged members of a Venezuelan gang to El Salvador over the weekend, where they have been imprisoned.