A Washington federal appeals court grappled Friday with the lawfulness of the Trump administration’s decision to wind down the Deferred Action for Childhood Arrivals program.

A three-judge panel for the U.S. Court of Appeals for the D.C. Circuit pressed both sides about the September 2017 move to undo the Obama-era policy, which deferred deportation for hundreds of thousands of immigrants who arrived to the United States as children. The panel is considering an appeal of U.S. District Judge John Bates’ ruling last year that the reversal was unlawful.