PHILADELPHIA (WPVI) -- More than a dozen women athletes have joined forces, but not to form a team. They've come together to file a lawsuit against the NCAA.
They say the organization violated Title IX by allowing transgender women to compete against cisgender women. The lawsuit was filed in Atlanta and names the NCAA, Georgia Tech and the University of Georgia, among others.
University of Pennsylvania swimmer Lia Thomas is mentioned throughout the lawsuit.
Thomas, who is transgender, was allowed to begin competing on the women's swim team in 2021, after coming out as transgender and taking hormone replacements for two years.
Thomas had previously competed on the men's swim team before her transition. She went on to win championships in women's swimming. Some women in the sport say she shouldn't be allowed to compete.
The lawsuit, which asks for a jury trial, says that by allowing transgender athletes like Thomas to compete, the NCAA is violating Title IX, which is a law meant to protect women in sports.
Pennsylvania Republican Representative Barbara Gleim agrees as co-sponsor of a bill named "The Fairness in Women's Sports Act."
"I applauded these women for standing up for themselves, standing up for Title IX and all of the rights we have fought for over the years," said Gleim.
The lawsuit involves more than a dozen women athletes, many of them swimmers. Several others compete in volleyball and track.
The lawsuit says, "Each Plaintiff's story demonstrates the harm being done to women that results from the NCAA's radical departure from Title IX's original meaning."
Long-time transgender advocate and activist Elizabeth Coffey-Williams says transgender women should be included in Title IX protections.
"Trans women are women. They're not perpetuating any type of fraud in order to dominate the sport," said Coffey-Williams
The lawsuit says athletes were shocked to both compete against Thomas and to share a locker room with her.
The NCAA says it can't comment on pending litigation, but that it will continue to "make unprecedented investments in women's sports and ensure fair competition in all NCAA championships."
"Biological males are going to have an advantage over females. It's not fair," said Gleim.
"Trans women are not always stronger or bigger. Additionally, there are many indicators that contribute to success in sport," said Coffey-Williams.
In addition to preventing transgender women from competing against cisgender women, the lawsuit also seeks to have wins and championships by transgender athletes like Thomas taken away.
Part of the lawsuit says, "The NCAA and its members are not above the law and must comply with it."
This national lawsuit could have an impact locally.
Rep. Gleim says, right now, the Fairness in Women's Sports Act is stuck in committee. She thinks a judgement against the NCAA in the national lawsuit could push the local bill forward.