Illinois has joined 13 other states in challenging an Indiana law banning transgender students from participating in school sports.

Attorney General Kwame Raoul and the 13 attorneys general filed an amicus brief in the case of A.M. v. Indianapolis Public Schools. In it, they maintain the court should affirm a preliminary injunction that allows a 10-year-old student who identifies as female to play on a school's girls’ softball team.

The student had been on the team in the past without issue. A new Indiana law prohibits transgender female students from taking part in girls' school sports.

A lower court determined the law likely violates Title IX of the Education Amendments of 1972 by denying transgender girls access to the same athletic opportunities as others.

"No student should face discrimination or restrictions on participating in extracurricular activities due to their gender identity," Raoul said. "I will continue to work to protect transgender youth from discrimination and allow them to participate equally in activities with their peers. My office will not stop advocating for all LGBTQ+ students."

A June study by the Williams Institute at the UCLA School of Law said more than 1.6 million people in the United States, including about 300,000 youth between the ages of 13 and 17, identify as transgender.

Other attorneys general joining Illinois are from California, Colorado, Delaware, the District of Columbia, Hawaii, Maine, Minnesota, New Jersey, New York, Oregon, Vermont and Washington.