Before 2016, service members who came out as trans were "caught in limbo," as NPR has previously reported. They weren't eligible for promotion, and were treated according to their gender assigned at birth. Troops who came out as trans could be discharged purely on the basis of their gender identity. Aspiring soldiers who were openly trans were considered unfit for duty.
In June 2016, after lengthy deliberation, the Pentagon announced a policy change. "Effective immediately, transgender Americans may serve openly," then-Secretary of Defense Ash Carter said. And within a year, he said, the military would no longer turn away recruits on the basis of trans identity. (The deadline was later extended by six months.)
Then, this July, Trump tweeted that "the United States Government will not accept or allow transgender individuals to serve in any capacity in the U.S. Military," an announcement that caught many people (including leaders at the Defense Department) by surprise.
The tweet was followed by an official presidential memo in August. The memo called for trans members of the military to, once again, be eligible for discharge based on their gender identity, and for would-be service members who are openly trans to be prohibited from joining the military, effective on Jan. 1, 2018.
The memo did not go as far as Trump's tweets. For instance, whether or not individuals currently serving would be discharged, among other elements of implementing the ban, would be up to Secretary of Defense Jim Mattis, according to the memo. Any steps taken should be "appropriate and consistent with military effectiveness and lethality, budgetary constraints and applicable law," the instructions stated.
Under the new preliminary injunction, this portion of the memo is unenforceable and the Pentagon policy is once again in effect. That means, unless the policy changes again, openly trans people could begin joining the military on Jan. 1.
The lawsuit against the Trump administration was initially filed by five anonymous service members, "Jane Doe" 1-5, from different branches, with decades of collective service and multiple overseas deployments between them. The "Jane Doe" plaintiffs were later joined by a "John Doe."
Two named plaintiffs, one at the Naval Academy and another in the Army ROTC, also joined the lawsuit as aspiring service members who, as openly transgender individuals, would be blocked from their career path by the president's memorandum.
The judge ruled that the plaintiffs have persuasive claims that their Fifth Amendment rights are being violated, and have a good chance of succeeding in their court case. She noted, among other things, that the president's policy was announced with little apparent deliberation, "disfavors a class of historically persecuted and politically powerless individuals" and contradicts the conclusions of military leaders.
She also wrote "the reasons given for [the directives] do not appear to be supported by any facts" — for instance, there is "practically no explanation at all" about how trans service members would harm "unit cohesion," she wrote.
The memo released by the president also prohibits the military from spending any resources on surgeries related to a service member's gender transition. Covering transition-related health needs was one of the policy changes the Pentagon announced in 2016.
Kollar-Kotelly said she could not issue a preliminary injunction on that element of the memo, because none of the plaintiffs in this case had proven that they would personally be harmed by that clause.
The Human Rights Campaign called the injunction "an important step in the ongoing efforts to protect transgender service members."
This case is not the only challenge to Trump's trans service member ban. The ACLU has a separate challenge pending in Maryland, on behalf of several named active service members.