The Department of Education concluded Monday that a suburban high school district outside of Chicago discriminated against a female transgender student on the basis of sex by denying her access to the girls’ locker room.

The government ordered the Palatine-based Township High School District 211 to give full access to girls’ locker rooms in the next month or lose federal funding, Reuters reported.

The American Civil Liberties Union brought a complaint to the Department of Education’s Office for Civil Rights on behalf of the student, who remains unnamed, in December 2013 after the student said she was denied access to the girls’ locker room and directed to change in a separate bathroom.

The district, which oversees seven high schools, says that transgender students are allowed to use the locker room for the gender they identify with if they shower and change privately. However, the government concluded that forcing students to use a separate changing place is a form of discrimination and violated federal non-discrimination rules.

"All students deserve the opportunity to participate equally in school programs and activities–this is a basic civil right," assistant U.S. Secretary for Civil Rights Catherine Lhamon said in a statement.

The school district labeled the agency’s conclusions "serious overreach," while the ACLU and the transgender student have celebrated them.

John Knight, the director of the LGBT and HIV Project of the ACLU of Illinois who is representing the student, accused the school district of "blatant discrimination" and "challenging my client’s identity as a girl."

"This decision makes me extremely happy–because of what it means for me, personally, and for countless others. The district’s policy stigmatized me, often making me feel like I was not a ‘normal person,’" the student said in a statement carried by the ACLU’s website.