WASHINGTON, Sept 3, 2025 (BSS/AFP) - A US federal appeals court ruled Tuesday against President Donald Trump's use of a wartime law to deport alleged Venezuelan gang members and blocked its use in some southern states.

Trump first invoked the 1798 Alien Enemies Act (AEA) on March 15 and flew two planeloads of alleged members of the Tren de Aragua gang to El Salvador's notorious maximum security CECOT prison.

The centuries-old law -- last used to round up Japanese-American citizens during World War II -- has since been targeted in a series of legal challenges.

The Fifth US Circuit Court of Appeals delivered a 2-1 ruling on Tuesday saying Trump could not rely on the law to deport migrants in Texas, Louisiana and Mississippi.

"We conclude that the findings do not support that an invasion or a predatory incursion has occurred," wrote judge Leslie Southwick.

"We therefore conclude that petitioners are likely to prove that the AEA was improperly invoked."

The Act allows the government to detain and deport citizens of hostile foreign nations in times of war or during an "invasion or predatory incursion."

Southwick, with judge Irma Carrillo Ramirez concurring, granted a preliminary injunction blocking removal.

Judge Andrew Oldham dissented, saying it depended on "matters of political judgment" to determine whether AEA's preconditions were met.

"From the dawn of our nation until President Trump took office a second time, courts have never second-guessed the President's invocation of that Act," Oldham wrote.

Legal challenges on Trump's use of the AEA are expected to eventually reach the Supreme Court.

Trump campaigned for president promising to deport millions of undocumented migrants, and a number of his executive orders on the issue have encountered pushback from judges across the country.

Since taking office, Trump has sent troops to the Mexican border, imposed tariffs on Mexico and Canada for allegedly not doing enough to stop illegal crossings, and designated gangs suchg as TdA and MS-13 as terrorist groups.

Another US federal appeals court last week temporarily blocked the Trump administration from stripping temporary protected status (TPS) from some 600,000 Venezuelans living in the United States.

According to the Pew Research Center, as of March 2024 there were 1.2 million people eligible for or receiving TPS in the United States, with Venezuelans making up the largest group.