President Donald Trump’s administration sued the California Department of Education on Wednesday, July 9, for allowing transgender girls to compete on girls sports teams, alleging the policy violates federal law.

The move escalates an ongoing battle between the Republican administration in Washington and Democratic-led California over trans athletes competing in girls and women’s sports.

The lawsuit filed by the Justice Department says California’s transgender athlete policies violate Title IX, the federal law that bans discrimination in education based on sex. The department says California’s rules “are not only illegal and unfair but also demeaning, signaling to girls that their opportunities and achievements are secondary to accommodating boys.”

“These discriminatory policies and practices ignore undeniable biological differences between boys and girls, in favor of an amorphous ‘gender identity,’” the lawsuit says. “The results of these illegal policies are stark: girls are displaced from podiums, denied awards, and miss out on critical visibility for college scholarships and recognition.”

California has a more than decade-old law on the books that allows students to participate in sex-segregated school programs, including on sports teams, and use bathrooms and other facilities that align with their gender identity.

Trump criticized the participation of a transgender student-athlete — AB Hernandez of Jurupa Valley High School in Riverside County — who won titles in the California track-and-field championships last month. Assistant Attorney General Harmeet Dhillon wrote in a letter after the meet that the sports body running the final violated the Equal Protection Clause of the Constitution by allowing trans girls to compete against other female athletes.

The federal Education Department earlier this year launched an investigation into California’s policies allowing athletes to compete on sports teams consistent with their gender identity. The agency said last month that the policies violate Title IX, and it gave the state 10 days to agree to change them. But the state this week refused.

Trump also sparred with Maine’s Democratic governor over the state’s transgender-athlete policies. Gov. Janet Mills told the president in February, “We’ll see you in court,” over his threats to pull funding to the state over the issue. His administration filed a lawsuit in April alleging Maine violated Title IX by allowing trans girls and women to compete against other female athletes.

Meantime, on his podcast in March, Gov. Gavin Newsom angered some party allies when he questioned the fairness of trans girls competing in girls sports. GOP critics have called on the governor to back a ban, saying his remarks do not square with his actions.

The issue is part of a nationwide battle over the rights of transgender youth in which states have limited transgender girls from participating on girls sports teams, barred gender-affirming surgeries for minors and required parents to be notified if a child changes their pronouns at school. More than two dozen states have laws barring transgender women and girls from participating in certain sports competitions. Some of the policies have been blocked in court.

Trump signed an executive order in February aimed at barring trans girls and women from participating on sports teams consistent with their gender identity.

Proponents of a ban, including the conservative California Family Council, say it would restore fairness in athletic competitions. But opponents, including the LGBTQ+ advocacy group Equality California, say bans are an attack on transgender youth.