The federal appeals court on Wednesday refused to lift the order that prevented the Trump administration from deporting Venezuelan migrants back to El Salvador following a wartime law dating back to the 18th century.

The U.S. Court of Appeals, District of Columbia Circuit, split into three judges upheld an order from March 15, temporarily banning deportations under the1798’s Alien Enemies Act.

For the first time in history, the Trump administration invoked the law to deport hundreds of people. The president issued a proclamation describing the Tren de Aragua as an invasion force.

The Justice Department appealed to U.S. District Court Judge James Boasberg after he blocked further deportations. He also ordered that planeloads of Venezuelan immigrants be returned to the U.S. This did not occur.

The lawsuit was filed by attorneys from the American Civil Liberties Union on behalf of five Venezuelans non-citizens being held in Texas.

The case has been a flashpoint in the escalating tensions between the White House and federal courts.