Public schools and courts across the country will be closely watching a Virginia case for guidance on restroom policies about gender and gender identity, a lawyer for a transgender teenager said Wednesday after a hearing before a Richmond-based federal appeals court.

"In some respects, this will be a bellwether," said American Civil Liberties Union attorney Joshua Block, who represents 16-year-old Gavin Grimm in a lawsuit challenging a policy that bars him from using the boys' restrooms at Gloucester High School.

He said that some other appeals courts have ruled in favor of transgender people on the basis of federal employment law or constitutional issues, but Grimm's case will be the first to determine whether policies such as Gloucester's violate the federal law against sex discrimination in education.

Grimm, who was born female but identifies as male, was allowed to use the boys' restrooms at his school for several weeks in 2014. But after some parents complained, the Gloucester County School Board adopted a policy requiring students to use either the restroom that corresponds with their biological gender or a private, single-stall restroom.

Board members said at the time that the policy respects the privacy of all students.

"Schools can and should have privacy protections, but what they can't do is exclude transgender students," Block told a three-judge panel of the 4th U.S. Circuit Court of Appeals.

Grimm is appealing a judge's dismissal of his sex discrimination claim and refusal to issue a preliminary injunction that would have allowed Grimm to use the boys' restrooms. The appeals court typically takes several weeks to issue a decision.

Block told the panel during the 45-minute hearing that multiple judicial rulings and federal regulations support Grimm's right to use the boys' restrooms. The U.S. Justice Department filed a "statement of interest" in Grimm's case in July declaring that failure to allow transgender students to use the restroom that corresponds with their gender identity amounts to sex discrimination under Title IX of the U.S. Education Amendments of 1972.

David Corrigan, an attorney for the school board, argued that the restroom policy is not discriminatory because anyone can use the alternative unisex restrooms.

"Our position is that all students are treated the same," he said.

Judge Andre Davis challenged Corrigan on that point, suggesting that "there's no stigmatizing impact" on anyone other than Grimm in having the private restroom as the only viable option.

Grimm said at a news conference after the hearing that he continues to struggle with the restroom policy, which he called humiliating and dehumanizing. He has little vocal support among his peers, he said, but also not much opposition.

"It's the elephant in the room nobody talks about," Grimm said. "In a way, that's worse."

He said he is waging the court battle for transgender students who come along after him, although it's not a duty he necessarily wanted.

"I did not set out to make waves," Grimm said. "I set out to use the bathroom."