Administration officials said they expect the fight over using the wartime act to ultimately head to the Supreme Court.

More than half of the 261 immigrants expelled to El Salvador on Saturday were swept out of the United States using a wartime powers act, a White House official said Sunday, amid questions about whether the Trump administration flouted a judge’s order barring use of the statute to hasten deportations.

President Trump says he’s using the 227-year-old law to crack down on Venezuela’s Tren de Aragua gang. The move is already facing a legal challenge. Here’s a look at key questions and answers about the Alien Enemies Act.