Some fear Trump’s invocation of the Alien Enemies Act could lead to abuses similar to those that took place during one of the darkest chapters of U.S. history.

Invoking the law could make it far easier for the Trump administration to detain and deport undocumented immigrants living in the U.S.

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.