The centerpiece of Donald Trump’s hardline attempts to deport undocumented immigrants using a wartime power has been met with resistance by federal courts, including among judges Trump himself has appointed.

A judge will hear arguments over the 20-year-old Venezuelan man deported to El Salvador whose removal violated a previous court settlement, according to a court order.

Even as the Administration refuses to reveal the names of those it has deported under the Alien Enemies Act, a network of lawyers and advocates is fighting to keep their cases alive.