Gavin Grimm, 19, sued the Gloucester County School Board after it banned him from using the boys’ bathroom. (Oliver Contreras/For The Washington Post)

The Virginia school board that was sued by a transgender student over its bathroom rules said Friday it is appealing a federal judge’s decision.

Gavin Grimm, now 19, sued the Gloucester County School Board when he was a high school sophomore. Grimm, who is transgender, said the school board’s policy barring him from using the boys’ bathroom was discriminatory.

Late last month, a federal judge ruled in his favor, saying that the board’s policy violated Title IX, which bars sex discrimination in public schools, and the Equal Protection Clause, which assures parity under the law.

In a brief filed Friday, the board’s attorney, David P. Corrigan, challenged the ruling. Corrigan argued that Title IX does not protect the right of transgender students to use bathrooms that align with their gender identity. He said the board’s policy, which requires students to use bathrooms according to their “biological sex,” is constitutional.

As Grimm’s case worked its way through the courts, it became the focal point of the battle between transgender student advocates who sought to allow students to use bathrooms aligned with their gender identity and opponents who argued that transgender students could compromise the privacy of others.

Grimm had the backing of the Obama administration, which filed briefs in his favor and argued the bathroom rule violated Title IX. The U.S. Court of Appeals for the 4th Circuit, based in Richmond, sided with Grimm in 2016, deferring to the Obama administration’s interpretation of Title IX.

Grimm’s case was appealed to the Supreme Court by the school board, and the court was set to hear it in spring 2017. But the Supreme Court sent Grimm’s case back to a lower federal court after the Trump administration reversed the guidance on transgender student rights.

Grimm’s attorney, Joshua Block of the ACLU, welcomed Friday’s appeal by the school district. Grimm is now a 19-year-old activist in Berkeley, Calif.

“The vast majority of courts have already made clear that these discriminatory and harmful policies violate Title IX,” Block said. “We’re confident that the 4th Circuit would agree.”