(CNN) A Chicago-area school district violated anti-discrimination laws by denying a transgender student full access to the girl's locker room, federal authorities said, the latest inquiry to side with students who feel discriminated against by school policies.

The finding against Township High School District 211 concerns only one of numerous complaints of discrimination made by transgender students.

Jazz Jennings became famous at age 6 when Barbara Walters interviewed her for a "20/20" segment about transgender children. Now 14, she hosts a popular series of videos on YouTube and is starring this summer in a TLC reality show about her life.

Jazz Jennings became famous at age 6 when Barbara Walters interviewed her for a "20/20" segment about transgender children. Now 14, she hosts a popular series of videos on YouTube and is starring this summer in a TLC reality show about her life.

Joshua Alcorn voiced a desire to live as a girl, but the Ohio teenager's parents said they wouldn't stand for that. In December 2014, Alcorn, 17, was fatally struck by a tractor-trailer on an interstate after leaving a suicide note that said in part, "To put it simply, I feel like a girl trapped in a boy's body." It was signed "Leelah." The case drew national attention to the plight of misunderstood transgender youth.

Joshua Alcorn voiced a desire to live as a girl, but the Ohio teenager's parents said they wouldn't stand for that. In December 2014, Alcorn, 17, was fatally struck by a tractor-trailer on an interstate after leaving a suicide note that said in part, "To put it simply, I feel like a girl trapped in a boy's body." It was signed "Leelah." The case drew national attention to the plight of misunderstood transgender youth.

After years as an androgynous male model, Australian Andrej Pejic underwent sex-reassignment surgery in 2014 and is now Andreja Pejic.

After years as an androgynous male model, Australian Andrej Pejic underwent sex-reassignment surgery in 2014 and is now Andreja Pejic.

On January 20, 2015, President Barack Obama became the first sitting U.S. president to mention the word "transgender" in a State of the Union address. Transgender activists hailed his speech.

On January 20, 2015, President Barack Obama became the first sitting U.S. president to mention the word "transgender" in a State of the Union address. Transgender activists hailed his speech.

Transgender activist and author Janet Mock attends the eighth annual Clinton Global Citizen Awards in New York in September 2014. Her 2014 memoir, "Redefining Realness," was a best-seller.

Transgender activist and author Janet Mock attends the eighth annual Clinton Global Citizen Awards in New York in September 2014. Her 2014 memoir, "Redefining Realness," was a best-seller.

Actor Jeffrey Tambor portrays a divorced father who begins transitioning to a woman in the Amazon series "Transparent," which debuted in February 2014. For his performance, Tambor won a Golden Globe for best actor in a TV musical or comedy series.

Actor Jeffrey Tambor portrays a divorced father who begins transitioning to a woman in the Amazon series "Transparent," which debuted in February 2014. For his performance, Tambor won a Golden Globe for best actor in a TV musical or comedy series.

Transgender model and reality TV personality Carmen Carrera attends a fashion show in September 2013 in New York. That year, thousands of fans signed a petition requesting that she be a model during the 2013 Victoria's Secret Fashion Show, but the campaign was unsuccessful.

Transgender model and reality TV personality Carmen Carrera attends a fashion show in September 2013 in New York. That year, thousands of fans signed a petition requesting that she be a model during the 2013 Victoria's Secret Fashion Show, but the campaign was unsuccessful.

"Orange Is the New Black" actress Laverne Cox attends an August 2014 event for Emmy nominees. Cox became the first openly transgender person to appear on the cover of Time magazine.

"Orange Is the New Black" actress Laverne Cox attends an August 2014 event for Emmy nominees. Cox became the first openly transgender person to appear on the cover of Time magazine.

Filmmaker Lana Wachowski attends a tribute to the late film critic Roger Ebert in October 2013 in Chicago. Born Larry Wachowski, he made the "Matrix" trilogy with brother Andy Wachowski before transitioning to living as a woman. Wachowski is the first major Hollywood director to come out as transgender.

Filmmaker Lana Wachowski attends a tribute to the late film critic Roger Ebert in October 2013 in Chicago. Born Larry Wachowski, he made the "Matrix" trilogy with brother Andy Wachowski before transitioning to living as a woman. Wachowski is the first major Hollywood director to come out as transgender.

Chaz Bono, the only child of entertainers Cher and Sonny Bono, arrives at a "Dancing With the Stars" special in May 2013. Bono was named Chastity at birth but came out as a lesbian in 1995 and later transitioned to living as a man. His transformation was chronicled in a book and a documentary feature, "Becoming Chaz."

Chaz Bono, the only child of entertainers Cher and Sonny Bono, arrives at a "Dancing With the Stars" special in May 2013. Bono was named Chastity at birth but came out as a lesbian in 1995 and later transitioned to living as a man. His transformation was chronicled in a book and a documentary feature, "Becoming Chaz."

The 2006 indie film "Transamerica" starred Felicity Huffman as a transgender woman taking a road trip with her long-lost teenage son. Huffman was nominated for an Academy Award for the role.

The 2006 indie film "Transamerica" starred Felicity Huffman as a transgender woman taking a road trip with her long-lost teenage son. Huffman was nominated for an Academy Award for the role.

Born female, Brandon Teena was living as a man in Nebraska when he was raped and killed by two men in 1993. Teena was 21. His case inspired the 1999 drama "Boys Don't Cry" starring Hilary Swank, who won an Oscar for her performance.

Born female, Brandon Teena was living as a man in Nebraska when he was raped and killed by two men in 1993. Teena was 21. His case inspired the 1999 drama "Boys Don't Cry" starring Hilary Swank, who won an Oscar for her performance.

Renee Richards, here in 2011, made headlines for undergoing a sex change while a professional tennis player in the 1970s. She was barred from playing as a woman in the 1976 U.S. Open but played in the tournament the next year after the New York state Supreme Court ruled in her favor and overturned the ban.

Renee Richards, here in 2011, made headlines for undergoing a sex change while a professional tennis player in the 1970s. She was barred from playing as a woman in the 1976 U.S. Open but played in the tournament the next year after the New York state Supreme Court ruled in her favor and overturned the ban.

Olympic gold medalist and reality TV star Bruce Jenner told ABC's Diane Sawyer, "Yes, for all intents and purposes, I'm a woman," during an interview that aired April 24. She has now made a highly publicized transition from male to female as Caitlyn Jenner.

Olympic gold medalist and reality TV star Bruce Jenner told ABC's Diane Sawyer, "Yes, for all intents and purposes, I'm a woman," during an interview that aired April 24. She has now made a highly publicized transition from male to female as Caitlyn Jenner.

The Girl Scouts of the United States of America now welcomes transgender girls, a stance that was made public several years ago but attracted controversy from conservative groups when it became widely known in May

Raffi Freedman-Gurspan is the first openly transgender White House staff member. She will serve as an outreach and recruitment director in the White House Office of Presidential Personnel.

Raffi Freedman-Gurspan is the first openly transgender White House staff member. She will serve as an outreach and recruitment director in the White House Office of Presidential Personnel.

It was rare for black models like Tracey "Africa" Norman to break into the cutthroat lily-white world of modeling in the 1970s. Norman, who had exclusive contracts for Avon skin care and Clairol's Born Beautiful hair color, didn't tell anyone she was also transgender and had been born male. Once her secret was out, the work dried up. Here are some other notable moments in the recent history of transgender identity.

It was rare for black models like Tracey "Africa" Norman to break into the cutthroat lily-white world of modeling in the 1970s. Norman, who had exclusive contracts for Avon skin care and Clairol's Born Beautiful hair color, didn't tell anyone she was also transgender and had been born male. Once her secret was out, the work dried up. Here are some other notable moments in the recent history of transgender identity.

In 2013, a Colorado court was the first to clearly rule that transgender people must be treated equally. The family of a transgender first-grader went to court after their school district stop allowing their daughter to use the girl's bathroom because she was born a boy. The ruling said such bans create a hostile, intimidating or offensive environment.

That same year , California became the first state to allow transgender students to choose which bathrooms and locker rooms to use.

The federal government has followed suit. Last year, the Obama administration announced that transgender people are protected from discrimination under the Civil Rights Act.

But the report announced Monday by the Department of Education might highlight how thin the line is that schools must follow.

Like other districts faced with this dilemma, the district tried to find a negotiated solution by putting up privacy curtains in the girls' locker room. Similar arrangements have kept schools from running afoul of anti-discrimination violations.

At Township High School District 211, however, the line between accommodation and discrimination came down to this: whether the student would be able to choose to use the privacy curtains, or whether the school could force her to do so.

The use of curtains might be OK, but the school can't have a policy that singles out this student for mandatory use of the privacy curtains, the Department of Education report states.

"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 student, who hasn't been publicly identified, participates on a girls' sports team, but has been required to change and shower separately from her teammates and classmates.

At public schools, the trend has been one of accommodation for students with different needs -- everything from wheelchair ramps to individual education programs, said Mara Keisling, executive director of the National Center for Transgender Equality.

Accommodating transgender students is not only the right thing to do, but an easy thing to do, she said.

"All that really has to happen here is the adults have to put their prejudices in check," she said. "These are just kids who are trying to go to school."

Adults have unfounded concerns that transgender students somehow disrupt class, Keisling said.

Policies that single out transgender students only further the isolation they might feel and set them up for bullying and even worse violence, she said.

In the Township case, the DOE launched the investigation following a 2013 complaint by the American Civil Liberties Union of Illinois, which is representing the student.

"The Department of Education's decision makes clear that what my school did was wrong," the student said in statement from the ACLU. "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."

The district defended its stance, saying it has been responsive to the needs of its transgender students.

"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.

Under the DOE's finding, the district has been given 30 days to reach a solution or face enforcement, which could mean the loss of Title IX funding. The federal law bans sexual discrimination.

"This decision makes me extremely happy -- because of what it means for me, personally, and for countless others," the student said. "The district's policy stigmatized me, often making me feel like I was not a 'normal person.'"