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 group of U.S. senators introduced legislation Thursday that would require the Trump administration to share reports on steps they are taking to comply with court orders surrounding deportations to El Salvador.

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.