A federal judge on Monday temporarily blocked a White House policy barring military service by transgender troops, ruling that it was based on “disapproval of transgender people generally.”

Judge Colleen Kollar-Kotelly of the Federal District Court for the District of Columbia found the administration’s justification for the ban, which was set to take effect in March 2018, to be suspect and likely unconstitutional. She ruled that the military’s current policy should remain in place.

“There is absolutely no support for the claim that the ongoing service of transgender people would have any negative effective on the military at all,” the judge wrote in a strongly worded, 76-page ruling. “In fact, there is considerable evidence that it is the discharge and banning of such individuals that would have such effects.”

Judge Kollar-Kotelly noted that the White House’s proposed policies likely violated the equal protection clause of the Constitution, writing that “a number of factors — including the sheer breadth of the exclusion ordered by the directives, the unusual circumstances surrounding the President’s announcement of them, the fact that the reasons given for them do not appear to be supported by any facts, and the recent rejection of those reasons by the military itself — strongly suggest that Plaintiffs’ Fifth Amendment claim is meritorious.”

Monday’s ruling was seen as an encouraging step for supporters. It stops a plan to discharge all transgender troops, allows current transgender troops to re-enlist and permits transgender recruits to join the military starting in January.

“She basically wiped the slate clean,” said Shannon Minter, a lawyer at the National Center for Lesbian Rights who represented the plaintiffs, adding that while the ruling could be appealed, he was confident that it effectively marked the end of the ban because the judge said it violated the Constitution.

Judge Kollar-Kotelly did not impose an injunction on the ban on sex reassignment surgery because she said it did not apply to any of the plaintiffs. But the plaintiffs’ lawyers argued that in blocking the entire policy, the ruling effectively shelved the ban on sex reassignment surgery as well.

In a statement, the Justice Department said, “We disagree with the court’s ruling and are currently evaluating the next steps.”

President Trump announced in a series of Twitter messages in July that American forces could not afford the “tremendous medical costs and disruption” of transgender troops, and said “the United States Government will not accept or allow them to serve in any capacity in the U.S. Military.” A presidential memorandum released in August required all transgender service members to be discharged starting in March 2018.

The announcement blindsided many in the military, which had been moving ahead with plans to integrate transgender troops, based on a 2016 study commissioned by the military that found that allowing transgender people to serve openly would “have minimal impact on readiness and health care costs” for the Pentagon.

It estimated that health care costs would rise $2.4 million to $8.4 million a year, representing an almost unnoticeable 0.04 to 0.13 percent increase in spending. The study also projected “little or no impact on unit cohesion, operational effectiveness or readiness.”

Civil rights groups immediately sued the administration on behalf of transgender service members, arguing that the ban was discriminatory and violated their constitutional right to due process and equal protection under the law. A number of lawsuits are still pending.

The government had asked that the case be dismissed, but Judge Kollar-Kotelly denied the motion, writing that while “perhaps compelling in the abstract,” the government’s arguments for dismissal “wither away under scrutiny.” Judge Kollar-Kotelly was nominated to a lower court in the District of Columbia by President Ronald Reagan and was named to the federal bench by President Bill Clinton.

The suit was filed by GLBTQ Legal Advocates and Defenders and the National Center for Lesbian Rights on behalf of five unnamed transgender women serving in the Coast Guard, Army and Air Force. Many of the women had served for years as men and had been deployed to war zones before coming out to commanders when the ban was lifted in 2016. One is a few years from retirement, according to court documents. Another told her commander she wanted to keep serving, but would resign if the military moved to forcibly discharge her.