PHOENIX (AP) — A federal appeals court has upheld a lower-court ruling that blocks Arizona from enforcing a 2022 law that bans transgender girls from playing on girls’ school sports teams.

In a decision Monday, a three-judge panel of the 9th Circuit U.S. Court of Appeals said the lower-court judge didn’t make an error in concluding that, before puberty, there are no significant differences between boys and girls in athletic performance.

The panel also concluded the law, on its face, discriminates based on transgender status.

The ruling applies only to two transgender girls whose parents filed a lawsuit challenging the law.

The parents’ lawsuit alleges the lawsuit violates the equal protection clause in the U.S. Constitution and Title IX. The appeals court says the challengers are likely to succeed on the equal protection claim, but the court did not say whether it thought the Title IX claim also would prevail.

The case will be sent back to the lower court, and the law will remain blocked while the case is litigated.

“We always expected to win this case in the U.S. Supreme Court,” Tom Horne, Arizona’s superintendent of public instruction, said Tuesday. “The 9th Circuit is notoriously left wing. We did not expect to get a fair hearing in the 9th Circuit.”

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Rachel Berg, an attorney for National Center for Lesbian Rights, which represents the girls and their parents, said the ruling “recognizes that a student’s transgender status is not an accurate proxy for athletic ability and competitive advantage.”

Arizona is one of several states and some school districts that have passed laws limiting access to school sports teams or other facilities to students on the basis of the sex they were assigned at birth rather than their gender identity.

Arizona officials have said the law passes federal muster because it aims at fairness.

LGBTQ+ rights advocates say bills like the one passed in Arizona and hundreds more across the U.S. are anti-transgender attacks disguised as protections for children and that they use transgender people as political pawns to galvanize GOP voters.