Alien Act: What to know about 1798 law that Trump invoked for deportations

The Supreme Court has allowed the Trump administration to use a 1798 wartime law, the Alien Enemies Act, to deport Venezuelan migrants it accuses of being gang members, ending the temporary halt on deportations ordered by a federal district judge.

But the court also ruled that the administration must give Venezuelans it claims are gang members the chance to legally fight any deportation orders. The ruling did not address the constitutionality of the act.

The Monday ruling came after the wartime law was used last month to fly more than 130 men accused of being members of the gang Tren de Aragua to El Salvador, where the U.S. has paid to have the men held in a notorious prison. The Trump administration argues that the gang has become an invading force.

The Venezuelans deported under the act did not get a chance to challenge the orders, and attorneys for many of the men say there's no evidence they are gang members. It remains unclear how the ruling will affect those men.

American Civil Liberties Union attorney Lee Gelernt said it was an "important victory" that people must now be given the right to challenge their removal orders.

The Trump administration welcomed the ruling, with Attorney General Pam Bondi saying an "activist judge in Washington, DC does not have the jurisdiction to seize control of President Trump's authority to conduct foreign policy."

Meanwhile, the administration is also looking to invoke the Alien Enemies Act to deport alleged members of the Salvadoran gang MS-13, Todd Lyons, acting Immigration and Customs Enforcement director, told reporters Tuesday during Border Security Expo, a trade show in Phoenix.

On Wednesday, federal judges in New York and Texas took legal action to block the government from deporting five Venezuelans under the act until they have the chance to challenge their removals. The government says the men are Tren de Aragua members. Their lawyers dispute that.

What is the Alien Enemies Act?

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.

Since then, the act has been used just three times: during the War of 1812 and the two world wars.

It was part of the World War II legal rationale for mass internments in the U.S. of people of German, Italian and especially Japanese ancestry. An estimated 120,000 people with Japanese heritage, including those with U.S. citizenship, were incarcerated.

Can the U.S. use a wartime law when it's not at war?

For years, Trump and his allies have argued that the U.S. is facing an "invasion" of people arriving in the country illegally.

Arrests on the U.S. border with Mexico topped 2 million a year for two straight years for the first time under President Joe Biden, with many released into the U.S. to pursue asylum. After hitting an all-time monthly high of 250,000 in December 2023, they dropped sharply in 2024 and dramatically more after Trump took office.

The Trump administration has increasingly described the migrant issue as a war, most notably by designating eight Latin American criminal groups, including Tren de Aragua and MS-13, as "foreign terrorist organizations."

Trump's invocation of the act, which was publicly announced March 15, the same day as the deportations, said Tren de Aragua was attempting "an invasion or predatory incursion" of the United States.

Administration officials now regularly use military terminology to describe the situation, with Trump telling reporters last month that "this is a time of war."

Trump's critics insist he is wrongly invoking an act designed for use during declared wars.

"Trump's attempt to twist a centuries-old wartime law to sidestep immigration protections is an outrageous and unlawful power grab—and it threatens the core civil liberties of everyone," Scott Michelman, legal director of the ACLU of the District of Columbia, said in a statement after the Monday ruling.

How has the legal case proceeded?

The ACLU and Democracy Forward preemptively sued Trump hours before the March 15 deportations began, saying five Venezuelan men held at a Texas immigration detention center were at "imminent risk of removal" under the Alien Enemies Act. U.S. District Judge James E. Boasberg blocked their deportation, prompting an immediate Justice Department appeal.

Later that day, Boasberg issued a new order to stop the deportations being carried out under the centuries-old law, and said any planes in the air needed to turn around. By then, though, two ICE Air planes were heading across the Gulf of Mexico and toward Central America. Neither came back.