The judgement trumps federal mandates for now.
On Tuesday, the Supreme Court of the United States (SCOTUS) allowed President Trump's policy in barring trans folks from enlisting and serving in the armed forces to go into effect. This decision overruled lower court decrees that put the ban on hold on the basis of constitutional rights.
Essentially, the conservative owned SCOTUS nullified any injunctions handed down by federal judges that allow trans folks to serve while the issue is contested in lower courts.
The justices who opposed the new policy are Ruth Bader Ginsburg, Stephen Breyer, Elena Kagan, and Sonia Sotomayor.
back in July of 2017, Trump made a seemingly impromptu declaration on Twitter announcing the ban.
“After consultation with my Generals and military experts, please be advised that the United States Government will not accept or allow transgender individuals to serve in any capacity in the U.S. Military,” he tweeted. “Our military must be focused on decisive and overwhelming victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail. Thank you."
The announcement caught the Pentagon and Capitol Hill off guard at the time, but was immediately applauded by anti-LGBT groups such as the Family Research Council.
The ban could once again be lifted should judgments in the cases of Trump v. Karnoski and Trump v. Stockman prove successful by the U.S. Court of Appeals for the Ninth Circuit.