The Trump administration is suing the state of Maine for refusing to ban transgender athletes from participating in women’s sports.
The move is an escalation in the public battle between the state’s governor and Donald Trump that has included threats from the president to cut funding to Maine’s education department.
President of the United States, Donald Trump.
In response, Maine’s Governor Janet Mills said the issue has “never been about school sports or the protection of women and girls”.
She also accused the federal government of “imposing its will” on states.
The dispute centres around Title 9, an American civil rights law that prohibits sex-based discrimination in education programs.
In February, Trump signed an executive order that prevents transgender women from competing in female categories of sports.
Also on Wednesday, in the UK, the Supreme Court ruled that the legal definition of a woman is based on biological sex.
The court said transgender people still have legal protection from discrimination.