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By Teo Armus

LGBTQ advocacy groups praised a federal judge’s decision to block President Donald Trump’s ban on transgender people in the military, hailing it as a first step in pushing back on a discriminatory order from the White House.

Judge Colleen Kollar-Kotelly ruled Monday that plaintiffs suing the White House over the ban were likely to win their case, writing “the reasons given for [the ban] do not appear to be supported by any facts.”

As the lawsuit makes its way through court, the ruling will force the military to revert back to its previous policy on transgender service members — one that protects them from being discharged on the basis of gender identity.

“This is a big boost of encouragement for our service members. It solidifies the fact that we are continuing to serve with honor,” said transgender Navy officer Blake Dremann, president of SPART*A, a group for LGBTQ service members and veterans.

Two of the plaintiffs in the lawsuit, the National Center for Lesbian Rights (NCLR) and GLBTQ Legal Advocates & Defenders (GLAD), called the ruling a “complete victory.”

“Our plaintiffs and all transgender service members … are now once again able to serve on equal terms and without the threat of being discharged,” NCLR Legal Director Shannon Minter said in a statement.

On a call with reporters Monday, he added that under the injunction, transgender people will be able to begin enlisting again in the military again on Jan. 1.

The lawsuit — which was filed by six anonymous transgender soldiers and two recruits — charges that Trump’s ban violates their rights to due process and equal protection, particularly after old policies instructed trans soldiers to come out to their chain of command.

Minter added that health care costs for trans service members, including gender reassignment surgery, will continue to be covered following the injunction. Trump’s ban would not have cut these funds until March.

Matt Thorn, executive director of LGBTQ military group OutServe, called Monday’s decision “a very big step in the right direction” for transgender members of the military.

As three other lawsuits challenging the ban are due to be heard across the country, Thorn — whose group filed one of these suits — told NBC News that the decision could lead to a permanent reversal of the ban.

“If there’s judges in all of these different cases coming to a similar decision, it’s sure to spark consensus that the judicial system overall is not agreeing with this guidance."

“If there’s judges in all of these different cases coming to a similar decision, it’s sure to spark consensus that the judicial system overall is not agreeing with this guidance,” he said.

Minter also said it’s promising that Kollar-Kotelly wrote that discrimination on the basis of gender identity counts as a form of sex discrimination — a contested claim that’s at the heart of several LGBTQ rights battles across the country.

The “exclusion of transgender individuals inherently discriminates against current and aspiring service members on the basis of their failure to conform to gender stereotypes,” Kollar-Kotelly wrote in her 76-page decision.

Department of Justice spokeswoman Lauren Ehrsam said in a statement to NBC News that the department disagrees with the ruling and is “currently evaluating next steps.”