In a precedent-setting case, federal authorities have accused the largest high school district in Illinois of violating federal discrimination laws by barring a male transgender student from having full access to the girls locker room.

The U.S. Department of Education's Office for Civil Rights said Monday that it found "a preponderance of evidence" that school officials at Township High School District 211, which is in Palatine, Ill., failed to comply with Title IX, a federal law that prohibits sex discrimination, reported the Chicago Tribune.

The Department of Education said the school district has one month to give the student, who is biologically a male but self-identifies as female, full access to the girls locker room. If the district refuses to comply, it could lose federal funding.

"All students deserve the opportunity to participate equally in school programs and activities - this is a basic civil right," Catherine Lhamon, assistant secretary for civil rights at the Department of Education said in a statement to Yahoo Health. "Unfortunately, Township High School District 211 is not following the law because the district continues to deny a female student the right to use the girls' locker room. The district can provide access to this student while also respecting all students' privacy. We encourage the district to comply with the law and resolve this case."

The student, whose identify has been kept private, participates on the girls sports teams and is allowed to use women's bathrooms. But the student said in a complaint with the Department of Education in 2013 that she has been required to change and shower separately from her teammates and classmates.

"The Department of Education's decision makes clear that what my school did was wrong," the student said in statement released by the American Civil Liberties Union of Illinois, which is representing her. "I hope no other student, anywhere, is forced to confront this indignity. It is a good day for all students, but especially those who are transgender all across the nation."

It's the first time such a decision on the rights of transgender students has been made, according to the Department of Education. All other previous cases have resulted in a settlement allowing transgender students equal access. In this case, the school district has fought back and says it is willing to go to court to defend its decision, according to Yahoo.

The high school defended its handling of the situation, saying it has accommodated the needs of its transgender students, but can only do so much in terms of the locker room request because of what they say are privacy violations of other students in the district, which serves more than 12,000 students, according to CNN. The district installed privacy curtains in the girls locker room as a compromise, but those were found to be in violation of federal law because they would have required the transgender student to use them, rather than giving her a choice.

"We do not agree with (the DOE's) decision and remain strong in our belief that the District's course of action, including private changing stations in our locker rooms, appropriately serves the dignity and privacy of all students in our educational environment," the district said in a statement.

The district superintendent, Daniel Cates, called the decision "a serious overreach with precedent-setting implications," according to The New York Times. Cates said the overwhelming majority of parents in the district made it clear that they favored "maintaining some measure of privacy expectation" in the locker rooms.

"We do stand on the position that we have not violated any laws," he said.