President Donald Trump invoked the Alien Enemies Act, a 1798 law giving him immense powers to deport noncitizens in a time of war. His use of that law was aimed at Tren de Aragua, a Venezuelan gang that he has repeatedly and falsely claimed as part of an invasion of criminal immigrants.

The government has deported hundreds of migrants over alleged gang ties, but their families claim their loved ones are innocent and lack due process.

A federal judge gave the government until the end of Monday to return a man to the US after it said it had mistakenly sent him to a prison in El Salvador in an “administrative error.”