Below is an explainer of what is set to happen:
Ban on Transgender military personnel
President Donald Trump announced in March he would restrict the military service of transgender people, who experienced a condition termed gender dysphoria, replacing an outright ban on trans service members which he had announced on Twitter in July 2017.
However, the ban has yet to come into force, because judges in federal courts in Washington state, California, and Washington, DC, refused to lift injunctions issued against banning transgender personnel in the military.
What’s happening in the courts
A showdown is now looming, as the Trump administration has lodged two appeals with the US Supreme Court, saying the lack of action is having a negative impact on the military.
One appeal asks to bypass the normal judicial review process, and have the transgender ban case heard immediately by the Supreme Court
The other – only to be considered if the first appeal is rejected – asks the court to put the transgender ban in place, while the case wends its way through the regular appellate courts.
“The injunction requires the military to maintain a policy that, in its own professional judgment, risks undermining readiness, disrupting unit cohesion, and weakening military effectiveness and lethality”, one administration motion said.
What opposition is there to this?
LGBT+ campaigners say the government has not pointed to anything concrete going wrong in the military to justify why the court should interfere with the normal judicial process.
“There have been no reported problems. And people have continued to serve honorably and courageously”, since the administration tried to impose the ban, said Jennifer Levi, transgender rights director for GLAD, an LGBT+ advocacy group.
What are campaigners doing?
Peter Renn, an attorney with LGBT legal advocacy group, Lambda Legal, is one of the lawyers representing Ryan Karnoski, who wanted to join the military as a social worker, and was the first to bring a case to court to try to stop the ban.
Karnoski and the other plaintiffs against the ban have until December 28 to file a brief against the administration’s appeal to put the ban in place if the court refuses to take up the case immediately.
Current and aspiring military service members have sued in courts around the United States after Trump announced his ban, which reversed Democratic former President Barack Obama’s policy of allowing transgender troops to serve openly, and receive medical care to transition genders.
If the Supreme Court did decide to take up the case, it would have to do so by January, Renn said, so there was time to hear arguments and deliberate by the end of its term in June.
How may people does this impact?
As of 2014, there were an estimated 2,450 transgender people serving in active duty in US forces, according to a 2017 RAND Corporation study that used a complex formula. Another 1,510 were estimated to be in the reserves.
The number on active duty in the US military is 1.3 million. More than 800,000 serve in the active reserves, according to the Pew Research Center.
The same study estimated costs for transition-related treatment would range from $2.4 million to $8.4 million a year.
Trump had mentioned that the cost of medical care was a factor in his original 2017 ban on transgender people in the military.
The annual budget of the Military Healthcare system is more than $43 billion, according to the Defense Department.
Jason Fields, Thomson Reuters Foundation, the charitable arm of Thomson Reuters