President Donald Trump was blocked by a federal appeals court from using an 18th-century wartime law, the Alien Enemies Act, to deport Venezuelan migrants his administration says belong to the criminal gang Tren de Aragua.

The 2-1 decision by the U.S. Court of Appeals for the Fifth Circuit found that there was not an “invasion or predatory incursion” by a foreign power as required by the 1798 statute to justify its invocation in the case of this group of migrants.

Trump has, through executive order, invoked the Alien Enemies Act by arguing that there is an invasion of the U.S. by foreign criminal gangs that his administration has now designated as terrorist groups.

The Alien Enemies Act was only used three times before in U.S. history, all during declared wars—in the War of 1812 and the two World Wars.

The Trump administration unsuccessfully argued that courts cannot second-guess the president’s determination that Tren de Aragua was connected to Venezuela’s government and represented a danger to the United States, meriting use of the act.

The decision bars deportations from Texas, Louisiana and Mississippi.

In the majority were U.S. Circuit Judges Leslie Southwick, a George W. Bush appointee, and Irma Carrillo Ramirez, a Joe Biden appointee. Andrew Oldham, a Trump appointee, dissented.

This is a developing article. Updates to follow.

This article uses reporting by The Associated Press.