A federal judge Saturday blocked President Donald Trump from using the Alien Enemies Act to immediately deport members of the Venezuelan gang Tren de Aragua, ordering any deportation flights underway as a result of Trump invoking the 1798 law return to the United States.

The order came after Trump on Saturday issued a proclamation, which he signed the day before, that relies on the 18th-century law to deport members of the Tren de Aragua gang, which he said “continues to engage in mass illegal migration to the United States to further its objectives of harming United States citizens.”
The Alien Enemies allows the deportation without a hearing of anyone from the designated enemy country who is not a naturalized citizen. The law has only been invoked three times while the country was at war, to hasten the removal of citizens of enemy countries.

Hours before the proclamation’s release, Chief U.S. District Judge James Boasberg in Washington, D.C., granted a temporary restraining order Saturday and ordered the government not to deport five Venezuelan nationals cited in a lawsuit brought by two nonprofits, Democracy Forward and the American Civil Liberties Union.