The lawsuit -- which also names Radwan's former coach, UConn's former athletic director and UConn's director of student financial aid -- alleges the defendants violated Radwan's right to free speech and due process, and that UConn breached her scholarship contract and violated Title IX.
Title IX regulations bar sexual discrimination at universities that receive federal funds.
The incident happened in November 2014, when the UConn Huskies defeated the University of South Florida on penalty kicks to win the American Athletic Conference championship.
In the celebration that followed on the field, Radwan, then a freshman, made the gesture at the camera as she embraced her teammates in victory. About a month later, she was informed the school was revoking her full athletic scholarship.
The lawsuit is based on the defendants characterizing Radwan's actions on camera as "serious misconduct," citing NCAA bylaws to justify revoking the scholarship. The lawsuit notes the definition of "serious misconduct" used by another NCAA conference, the Southeastern Conference, is "sexual assault, domestic violence or other forms of sexual violence."
The lawsuit also alleges that UConn discriminated against Radwan by subjecting her to different disciplinary actions than male student athletes, citing a UConn football player who had been cited by officials for unsportsmanlike conduct during a game and faced no discipline and another football player who got in a fight and was arrested but was not suspended from the team.
"While her conduct during the incident was unsportsmanlike, it was not 'severe misconduct' such that it warranted the revocation of her scholarship midyear," the suit says.
The suit alleges Radwan's coach at the time, Len Tsantiris, used the middle finger incident as an excuse to give Radwan's full athletic scholarship to a student from Notre Dame who he was hoping would transfer if offered the funding.
"Although the lawsuit has been provided to the media, it hasn't yet been served on the University," said Tom Breen, deputy spokesperson for UConn. "We're also not in a position to discuss individual students' cases due to provisions in the Family Educational Rights and Privacy Act, unless and until they provide the university with a signed waiver."
Then-athletic director Warde Manuel could not be reached for comment.
Radwan, who left UConn when she lost her scholarship and is now a junior playing soccer with a partial scholarship at Hosftra University, spoke at a news conference on Monday.
"Finally, today I can speak publicly to apologize to the University of Connecticut's student body and administration for my emotional moment of misjudgment. ... I was making a celebratory statement that was seriously misinterpreted and misjudged," she said. "I loved UConn, but I lost faith in it as an institution when it allowed my scholarship to be illegally taken away so abruptly and crassly in the middle of the school year, violating all trust I had."