The 5-4 split saw the court's five conservative justice uniting in favor of allowing President Donald Trump's effort to ban openly transgender service to go ahead while the four liberal justices would have allowed nationwide injunctions to stay in place as the case played out.
It is currently winding its way through lower courts as the Trump administration seeks to undo former President Barack Obama's policy of allowing transgender men and women to serve openly in the military and to allow them to have government-funded sex-reassignment surgery.
Trump tweeted in July 2017 that his administration would not allow “transgender individuals to serve in any capacity in the U.S. Military."
The president said the military "cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail."
Trump's decision was met with legal challenges on behalf of active duty transgender military personnel who said it could result in their removal from the military and loss of medical services.
Former Defense Secretary James Mattis sought to amend the policy, seeking to bar those who identify with a gender different than that which they were born with, but making exceptions for those already serving openly and those who would serve under their biological sex.
That policy was met with injunctions by federal court judges that the Supreme Court overturned Tuesday.
The American Civil Liberties Union called the court's decision "deeply upsetting," but said on Twitter that it did not "lift the nationwide block secured in our case, Stone v. Trump, which is before a court in Maryland."
That case is on behalf of 12 transgender members of the armed forces, arguing the ban violates the constitution's equal protections clauses.