A Supreme Court decision pushing for the return of a man mistakenly deported to a Salvadoran prison has both his lawyers and the Trump administration claiming victory, leaving unclear if and when Kilmar Abrego Garcia will return home.

Such a ruling puts down a marker that can be a check on the Trump administration’s claim that the president alone had the power to decide who is arrested and deported. It also will slow the pace of deportations. Hundreds of prisoners were deported on March 15 only because none of them were given a legal right to challenge their removal.

In a unanimous decision, the Supreme Court sharply criticized the Trump administration for illegally deporting Kilmar Armando Abrego Garcia to El Salvador, ordering the U.S. to take action toward his release.