A federal judge blocked the Trump administration on Tuesday from banning transgender people from serving in the military.

In a forcefully written opinion that rebuked the president’s effort, U.S. District Judge Ana C. Reyes issued an injunction that allows trans troops to keep serving in the military, under rules that were established by the Biden administration, until their lawsuit against the Trump administration’s ban is decided.

“The ban at bottom invokes derogatory language to target a vulnerable group in violation of the Fifth Amendment,” Judge Reyes wrote.

According to the Defense Department, about 4,200 current service members, or about 0.2 percent of the military, are transgender. They include pilots, senior officers, nuclear technicians and Green Berets as well as rank-and-file soldiers, sailors, airmen and Marines. Despite their relatively small numbers, they have been a disproportionate focus of the Trump administration.

In January, President Trump signed a caustically worded executive order saying that trans troops had afflicted the military with “radical gender ideology,” and that the “adoption of a gender identity inconsistent with an individual’s sex conflicts with a soldier’s commitment to an honorable, truthful and disciplined lifestyle, even in one’s personal life.”

In February, the Defense Department issued new policies that included the same language, and said that all trans troops, regardless of merit, would be forced out of the military.