The Department of Justice has opened an investigation into a California law that permits transgender athletes to participate on female teams at state schools.

Harmeet Dhillon, the assistant attorney general who heads DOJ's Civil Rights Division, sent letters of legal notice Wednesday to California Attorney General Rob Bonta, a Democrat, Tony Thurmond, state superintendent of public instruction, the Jurupa Unified School District, and the California Interscholastic Federation, DOJ said in a news release.

DOJ is investigating whether AB 1266, a law signed by then-Gov. Jerry Brown in 2013 that allows transgender athletes to compete in the gender with which they identify, violates Title IX, which prohibits sex-based discrimination in education programs and activities that receive federal funding.

President Donald Trump issued an Inauguration Day executive order that reversed the Biden administration's interpretation of Title IX from requiring gender identity-based access to single-sex spaces to sex-based distinctions in activities.

The order declared that it is federal policy to recognize two sexes, male and female, and that they are "not changeable and are grounded in fundamental and incontrovertible reality."

"Title IX exists to protect women and girls in education," Dhillon said in the news release. "It is perverse to allow males to compete against girls, invade their private spaces, and take their trophies. This Division will aggressively defend women's hard-fought rights to equal educational opportunities."

The letters of legal notice were sent at the same time DOJ filed a statement of interest in federal court in support of a lawsuit filed by and on behalf of female athletes to advance the appropriate interpretation of Title IX to ensure equal educational opportunities and prevent discrimination based on sex in federally funded schools and athletic programs.

The lawsuit alleged the California bill "is harming hundreds — if not thousands — of female students by removing opportunities for female athletes to be champions in their own sports, robbing them of podium positions and awards, and creating unsafe and intimidating environments in their bathrooms and locker rooms."

California has been in the spotlight since a transgender athletes, AB Hernandez of Jurupa Valley High School, won the long jump and triple jump at the CIF Southern Section Division 3 girls championships on May 17, and at the CIF Masters meet (which combines all divisions).

Trump threatened to cut federal funding to the state over the issue, spurring the CIF to alter its policy by allowing girls to compete in the state championships who would have otherwise qualified if a transgender athlete previously "won."

"The law is clear: Discrimination on the basis of sex is illegal and immoral," said Bill Essayli, the U.S. attorney for the Central District of California, in the news release. "My office and the rest of the Department of Justice will work tirelessly to protect girls' sports and stop anyone — public officials included — from violating women's civil rights."

State officials, though, denounced the investigation Wednesday, vowing to uphold their laws.

"We remain committed to defending and upholding California laws and all additional laws which ensure the rights of students, including transgender students, to be free from discrimination and harassment," Bonta's office said in a statement, according to the California Globe. "We will continue to closely monitor the Trump administration's actions in this space."

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