WASHINGTON—On Monday the Supreme Court threw out a major transgender lawsuit, sending the case back to a lower federal court in light of the Trump administration’s rescinding of an Obama policy implicated by the lawsuit.

High school student “G.G.” (later revealed as Gavin Grimm) is a biological teenage girl who calls herself a boy and dresses as a boy, supported in her transgender identity by her mother. They asked her teachers and the staff at her school in Gloucester County, Virginia, to likewise treat her as a male student.

School officials tried to accommodate G.G., calling her by her preferred boy’s name Gavin, but asked that she use the unisex bathroom in the nurse’s office rather than use the boys’ bathrooms and locker rooms alongside biological boys and adult men.

Encouraged by her lawyers from the ACLU, G.G. demanded the school allow her to use the boys’ bathrooms and locker rooms at the same time that biological males are using those facilities. The school board instead adopted the policy that everyone must either use facilities matching their biological sex or single-person unisex bathrooms.

G.G. sued, arguing that Title IX of federal law requires schools to allow everyone to use whichever facilities they identify with. Acting Deputy Assistant Secretary James Ferg-Cadima from Barack Obama’s Education Department agreed with her position.

The U.S. Court of Appeals for the Fourth Circuit sided with the Obama administration, holding that the term “sex” in federal law is ambiguous, and that courts should defer to Ferg-Cadima’s private letter as an authoritative declaration of law.

Subsequent to Ferg-Cadima’s letter, Obama’s Justice Department and Education Department issued a joint “Dear Colleague” letter as an official policy, declaring that both Title IX and Title VII—which generally prohibits employers from discriminating on the basis of sex—require all schools and employers to embrace transgender policies, and that anyone declining to do so can be sanctioned for violating federal law.

However, on Feb. 22, 2017, the Trump administration rescinded the Dear Colleague letter.

Evidently thinking it likely that this policy change nullifies Ferg-Cadima’s letter, the Supreme Court has now vacated the Fourth Circuit’s decision, sending the case back to the Fourth Circuit for further proceedings.

Ken Klukowski is senior legal editor for Breitbart News. He is also senior counsel for First Liberty Institute and filed an amicus brief at the Supreme Court representing Catholic colleges in this case. Follow him on Twitter @kenklukowski.