In March 2025, President Trump issued an executive order invoking a centuries-old law: the Alien Enemies Act. The Act allows a president to detain or deport citizens of foreign adversaries to the United States, but only in the case of a "declared war" or "invasion." Now, the Trump administration and the courts are locked in a battle over whether the president's use of the Act, under which people have already been deported, is legal.

Today on the show: where the Alien Enemies Act came from, how presidents have used it before, and what that tells us about what's to come.

Guest:

Daniel Tichenor, professor of political science at the University of Oregon

To access bonus episodes and listen to Throughline sponsor-free, subscribe to Throughline+ via Apple Podcasts or at plus.npr.org/throughline.