Five active duty transgender service members have filed the first lawsuit against President Donald Trump's directive to prohibit transgender individuals from serving in the armed forces.
The unnamed plaintiffs filed the lawsuit on Wednesday under the pseudonym - "Jane Doe" Nos. 1-5 - in the US District Court for the District of Columbia, The New York Times reported.
The lawsuit complaint argued that banning transgenders from serving in the military would be unconstitutional discrimination, violating their rights to equal protection and due process.
It also argued that the administration could not end people's military careers for coming out openly as transgender because they did so in relying on the Pentagon itself saying they would be permitted to serve.
The case was organised by two rights groups, the National Centre for Lesbian Rights and GLBTQ Legal Advocates and Defenders (GLAD).
Other rights groups -- like Lambda, Outserve and the American Civil Liberties Union -- have also said that they were preparing lawsuits but are holding off until the Trump administration takes a step to put the ban into effect, such as issuing formal guidance to the military or beginning the process of changing military rules.
The lawsuit was filed in response to Trump's ban abruptly announced last month on Twitter.
He stated that the government "will not accept or allow transgender individuals to serve in any capacity in the US Military".
However, the ban is yet to be formally implemented, but attorneys for the service members have asked a federal court in Washington to block it immediately, reports The New York Times.
US Joint Chiefs of Staff Chairman General Joseph Dunford said the Pentagon would not change the current policy until the White House issues further "guidance".
A 2014 study by the Williams Institute at the University of California, Los Angeles, estimated that about 8,800 transgender people were serving on active duty, with thousands more in the National Guard and reserve.
A 2016 study by the RAND Corporation estimated that there were about 2,450 such active-duty troops.
In 2016, the former Obama administration lifted a prior ban on transgender troops that permitted transgender members currently serving to come out openly.
Openly transgender people are set to be allowed to join the military starting next year.