WASHINGTON — Both the transgender teen who sued to use a boys bathroom and the Virginia school board that won’t let him still want the Supreme Court to issue a definitive ruling in their ongoing dispute, even after the Trump administration retreated from an Obama-era policy on bathroom use.

The big issue for both sides is whether the main federal law barring sex discrimination in education protects high school senior Gavin Grimm and other transgender students.

Grimm was born a girl but identifies as a boy. The Virginia teen has been issued an amended birth certificate identifying him as a male, received hormone treatments and underwent chest reconstruction surgery.

His lawyers said in court papers filed Thursday that prohibiting him from using the boys restroom is discrimination “on the basis of sex.”

The Gloucester County school board said the law known as Title IX was “intended to erase discrimination against women in classrooms, faculties and athletics.” It does not include gender identity, the board said.

But the withdrawal on Wednesday of joint Education and Justice Department guidance to school systems gives the high court an easy out if it is seeking to avoid a major ruling on transgender rights. The appeals court that sided with Grimm relied on the Obama administration’s reading of the anti-discrimination law and an Education Department regulation to hold that Grimm should be allowed to use a restroom that conforms to his chosen gender.

The Trump administration’s decision to abandon Obama’s guidance set off tensions within the Cabinet. Education Secretary Betsy DeVos expressed reluctance to rescind protections for transgender students and clashed with Attorney General Jeff Sessions, who supported it, according to a person familiar with the conversations but not authorized to speak publicly about internal discussions and so requested anonymity.

After the announcement, DeVos released her own statement, stressing that the administration had a “moral obligation” to protect LGBT students, which she said was “not only a key priority for the department, but for every school in America.” Speaking Thursday to the Conservative Political Action Conference, however, she framed it as a legal matter, “a very huge example of the Obama administration’s overreach.”

The court on Thursday asked both sides to say what they think it should do following the administration’s action.

Now that the basis for the appellate ruling has disappeared, the justices could return the case to the 4th U.S. Circuit Court of Appeals in Richmond, Va., and direct it to decide for itself what the law and regulation require. No appeals court has yet to do so and the high court typically won’t take up a major legal issue until after several courts around the country have weighed in.