Immediately after the attack on Pearl Harbor, President Franklin D. Roosevelt claimed the Alien Enemies Act of 1798 authorized government round-ups of Japanese immigrants without a declaration of war, warrants, or formal charges. Assuming without evidence or trials that all Japanese Americans were spies and saboteurs, officials then ordered the mass removal and incarceration of more than 126,000 Japanese Americans. We examine the impact of the Alien Enemies Act on Japanese Americans during World War II; Donald Trump’s unconstitutional invocation of the act to arrest, detain, and deport Latinx migrants and other people of color; and recent protests by Japanese American incarcerees and their descendants against Trump’s illegal, xenophobic and racist application of the Alien Enemies Act.