Trump wants to use a 226-year-old law to deport millions of undocumented migrants. Can he do it?

Donald Trump’s plan to deport millions of undocumented migrants could potentially rely on a 226-year-old law, the Alien Enemies Act, which was last invoked during World War II to detain non-citizens of Japanese, German, and Italian descent.

The 1798 Alien Enemies Act allows the U.S. president to target foreign nationals from specific countries during times of war or when a foreign government is perceived as threatening or invading U.S. territory. Trump has mentioned using this law to fulfill his campaign promise of initiating the “largest deportation program in American history,” which could face delays due to the complexities of the immigration court process.

Legal experts suggest that if Trump pursued standard procedures, deportation would be a slow process, as individuals would need to go through immigration court proceedings to determine whether they are deportable or eligible for relief, such as asylum. With a backlog of 3.7 million cases in immigration courts and only 700 judges, cases are being scheduled years in advance.

This slow process would require significant funding to hire more agents, judges, and detention facilities, with some estimates suggesting that a mass deportation operation could cost over $300 billion. This is why Trump might turn to the Alien Enemies Act, which was first enacted when the U.S. was on the brink of war with France in the late 1700s. The law was designed to prevent espionage and sabotage by foreign nationals and allows for deportation without due process if the individual is from a country the U.S. is at war with or perceives as a threat.

The law has been used three times in U.S. history—during the War of 1812, World War I, and World War II, when President Franklin D. Roosevelt used it to detain non-citizens from enemy countries. Supporters of Trump’s plan argue that the situation at the U.S.-Mexico border, characterized by unlawful migration and cartel activity, qualifies as an “invasion,” potentially justifying the use of the Alien Enemies Act for deportations.

However, critics argue that this interpretation is flawed, as there is no foreign nation or government perpetrating the so-called invasion. They argue that gangs, cartels, or migrants themselves should not be considered “foreign governments” under the law. Furthermore, legal scholars note that the U.S. is not at war with immigrants, and any attempt to characterize deportations as a wartime action would face substantial legal challenges.

While some believe courts might treat this as a political issue beyond judicial resolution, the logistical challenges of implementing mass deportations would remain. Experts warn that even if Trump pursued this route, it would take significant time and resources to detain and deport large numbers of people, making immediate mass deportations unlikely.