The U.S. Department of Education (DOE) on Thursday informed Denver Public Schools (DPS) that its decision to create all-gender bathrooms at one of its schools violated Title IX, the federal law banning sex discrimination in education.

In a Jan. 27 letter to the Colorado district, the Office for Civil Rights (OCR) within the DOE began an investigation after a girls’ bathroom at East High School was converted into an all-gender restroom. District officials said the move put them in conflict with federal policy under Title IX.

DPS officials said they redid a restroom at the school to be gender-neutral while a restroom on the same floor remained for boys only. The move came after a student-led process and design principles, district leaders added, and all the stalls in the newly constructed bathroom had 12-foot-tall partitions surrounding the toilets.

Federal officials said the changes violated Title IX, with the department’s Acting Assistant Secretary for Civil Rights, Craig Trainor, saying in a statement that it “denied students equal access to the facilities, and also fostered what our Office for Civil Rights found to be a ‘hostile environment’ under Title IX.”

The district said it brought another all-gender bathroom to the same floor to address equity concerns. DPS officials also said students could use other sex-separated bathrooms in the school, as well as single-stall, all-gender restrooms.

The DOE sent a resolution plan to Denver Public Schools on Thursday that proposed four conditions it must meet within 10 days to avoid further action.

The resolution states that the Colorado district:

Must redesignate all all-gender multi-stall restrooms as either male or female.

Must not have policies, practices, or any other provisions that allow students to access any of the district’s bathrooms or other intimate facilities on the basis of gender identity instead of their biological sex.

Must “use and apply biology-based definitions of ‘male’ and ‘female’ in all of its policies, practices, and other actions” relevant to Title IX.

Must issue a memo to schools that restrooms “must protect the privacy, dignity, and safety of students” and be “comparably available to both sexes.”

The letter added that DPS could request a hearing with the DOE to contest any of the terms. However, not meeting them within the timeframe “may result in enforcement proceedings, including the potential termination of federal funds to Denver Public Schools.”

Trainor said in a statement that the move to create an all-gender restroom and allow students to use bathrooms that did not correspond with their biological sex “endanger student safety, privacy, and dignity.”

“Denver Public Schools violated Title IX and its implementing regulations by converting a sex-segregated restroom designated for girls in East High School to an ‘all-gender’ facility and by allowing students to use the high school’s intimate facilities on the basis of their gender identity rather than their biological sex,” he said.

“Denver is free to endorse a self-defeating gender ideology, but it is not free to accept federal taxpayer funds and harm its students in violation of Title IX,” Trainor continued. “The Trump Administration will work relentlessly to hold accountable school districts that harbor the ideological fanatics and policies that sully students’ educational experience with sex discrimination.”

Denver Public Schools has maintained that students led the creation of all-gender restrooms. District officials have also emphasized that student needs were at the center of the decision while taking student privacy and safety into account.

DPS has not publicly responded to the latest developments from the DOE but has said students still had several bathroom options including single-stall all-gender facilities for those who want more privacy.

The case in Denver is the latest skirmish in a broader national fight over gender identity in schools. In an executive order this year, President Donald Trump prohibited transgender girls from joining sports teams that do not align with their biological sex.

GOP lawmakers have also introduced legislation in Congress that would prevent transgender students from using bathrooms or participating on teams that match their gender identity.

The DOE has pursued several gender-based cases at schools and universities. Earlier this week, the agency determined George Mason University had engaged in unlawful diversity, equity, and inclusion (DEI) practices under Title VI.

Denver Public Schools now must decide if it will comply with the proposed federal resolution or face enforcement action that could risk its federal funding.

The district has 10 days to respond to the DOE and decide if it will rescind its all-gender bathroom policy.