The U.S. Department of Education said Thursday that Denver Public Schools violated federal law by creating all-gender bathrooms and allowing students to use facilities based on their gender identity, not their biological sex.

The agency said in a letter that its Office for Civil Rights opened an investigation into the district’s policy in January, following the conversion of a girls’ restroom into an all-gender facility at East High School. Education officials said the move was at odds with the federal government’s interpretation of Title IX, a law that bans sex-based discrimination in schools.

District officials said at the time that the decision came following a student-led process that resulted in the creation of all-gender bathrooms. Officials said the new bathrooms, which replaced a girls’ restroom, featured 12-foot-tall partitions around each toilet in the facility to ensure student privacy and security.

The letter from the Office for Civil Rights said the bathroom change violated Title IX regulations by “arbitrarily restrict[ing] the ability of other students to access sex-segregated restrooms,” according to Acting Assistant Secretary for Civil Rights Craig Trainor. The decision, the federal government said, created a “hostile environment” by denying students “equal access to the school’s restrooms.”

The district later opened a second all-gender restroom on the same floor to resolve complaints of fairness. Officials have said the district also maintains all boys’ and girls’ bathrooms, and there are single-stall, all-gender restrooms elsewhere in the school.

The federal government issued a proposed resolution with a list of conditions it said the district must fulfill to avoid an enforcement action. The conditions include redesignating the all-gender, multi-stall restrooms back to facilities for a specific sex, and the district must agree to the proposed resolution within 10 days, according to the letter.

District would Have to Amend Policies

If the district signs off on the resolution, it will also have to eliminate the use of policies that allow students to access bathrooms that correspond with their gender identity. Denver Public Schools would also have to amend all Title IX-related policies and practices to include “biology-based definitions” for the words “male” and “female.”

District officials would also have to issue a memorandum to schools that the “use of the school’s restrooms must not only ensure the privacy, dignity, and safety of all students, but also comparably open access to both boys and girls,” according to the federal government.

Failure to agree to the resolution could lead to the Education Department enforcing the law, which could mean the district would lose access to federal funding.

Education Department Finds Gender Identity Policies Violated Federal Law

Federal government officials said the district’s decision to allow students to use bathrooms based on gender identity, not biological sex, was in violation of Title IX.

“This policy … endangers student safety, privacy, and dignity,” Trainor said in a statement. “Denver Public Schools violated Title IX and its implementing regulations by designating a restroom that was previously sex-segregated and used only by girls at East High School as an ‘all gender’ facility and by allowing students to use the high school’s intimate facilities based on their gender identity rather than their biological sex.”

Trainor said in the statement that federal law does not recognize gender ideology, and the district’s decision “does not comport with Title IX.”

President Donald Trump has also expressed support for school bathroom policies that are based on students’ biological sex. This year, he signed an executive order that bars transgender girls from playing on sports teams that align with their gender identity.

GOP lawmakers in Congress have introduced legislation that would also ban transgender students from using bathrooms that align with their gender identity and block them from joining sports teams that align with their gender identity.

Department Acts on Multiple Cases

The Education Department has opened multiple cases against schools and universities over their policies and practices when it comes to gender identity and definitions.

Just this week, the department said the George Mason University violated federal law over “diversity, equity, and inclusion” practices under Title VI. Earlier this month, the department reached a settlement with a public university in California to change its housing policies.

Denver Public Schools must make a decision within the next 10 days as to whether to accept the proposed federal resolution. If it does not, it could face an enforcement action that puts millions of dollars in federal funding at risk.

The district has not commented on the letter and could still have the opportunity to roll back its all-gender bathroom policy in a negotiated settlement with federal officials.