Gavin Grimm at his home. The transgender teen sued the Gloucester County School Board after it barred him from the boys' bathroom. (Nikki Kahn/The Washington Post)

The legal journey of a Virginia transgender teen took a step back on Wednesday when a federal appeals court said it would not immediately take up his fight to use the boys’ bathroom.

Attorneys for Gavin Grimm, whose case was earlier put off by the Supreme Court, had hoped to have his challenge to the Gloucester County School Board heard by a federal appeals court before his graduation in June.

Because Grimm no longer is a high school student, the U.S. Court of Appeals for the 4th Circuit said Wednesday that a lower court must sort out whether Grimm still has enough of an affiliation to his alma mater to pursue the case.

“Because all of the prior litigation was conducted while Grimm was a student, the parties have presented us with nothing more than unsupported assertions regarding Grimm’s continued connection to his high school and the applicability of the school board’s policy,” according to the order from Judge Paul V. Niemeyer, who was joined by Judges Allyson K. Duncan and Henry F. Floyd.

“We remand this to the district court for the limited purpose of resolving, in the first instance, whether this case has become moot.”

The unanimous order from the three-judge panel is a setback to Grimm’s efforts to allow transgender students to use bathrooms matching their gender identities. Grimm’s case had been scheduled for oral argument at the Richmond-based 4th Circuit in September.

“Gavin’s life is going by while these procedural steps happen,” said Joshua Block, an American Civil Liberties Union attorney for Grimm, now 18. “It’s another detour on his way to having his day in court.”

In March, the Supreme Court put off a ruling in Grimm’s case after the Trump administration revoked Obama administration-era guidelines directing U.S. public schools to accommodate transgender students.

The high court’s move sent Grimm’s case back to the 4th Circuit. The appeals court earlier had sided with Grimm and deferred to the Obama administration guidelines on transgender rights released in May 2016.

Advocates for lesbian, gay, bisexual and transgender rights had hailed the move, but it was criticized by many conservatives, who said the administration was overreaching and violating the privacy of children.

At Gloucester High, Grimm had been forced to use a restroom separate from his peers. In recent court filings, Grimm’s lawyers told the 4th Circuit that the teenager’s “future attendance at alumni and school-community events” was enough of a connection to allow the court to continue to consider the case.

Attorneys for the Gloucester County School Board said that unless Grimm stated a “particular intention to return to school after graduation,” his alumni status made the case moot. The bathroom policy does not necessarily apply to alumni, the school board said in its filing.

The appeal to the 4th Circuit was limited to a preliminary injunction to stop the school board from enforcing its bathroom policy. Grimm’s claims of discrimination have been on hold in district court pending the resolution of the injunction.