In March, a group of University of Wyoming girls filed a lawsuit against their sorority’s national organization for allowing a male student to join the sisterhood and invade their private spaces.

The male student, referred to as Terry Smith in the suit, is a 21-year-old, 6-foot, 260-pound man who identifies as a woman. He has full access to the sorority’s on-campus house, including the girls’ communal restrooms and bedrooms, and has made a number of girls fear for their privacy and safety. In one incident, a girl said she was heading to the shower, wearing only a towel, when she “felt an unsettling presence, turned, and saw Mr. Smith watching her silently,” according to the lawsuit.

On another occasion, after a sleepover at the sorority house, Smith stood in a corner of the common room, watching girls change out of their pajamas. One girl, who did not realize Smith was there, changed out of her pajama top, and when she turned around, she found Smith staring at her. Other girls later revealed to her that Smith put “his hands over his genitals” because he had become sexually aroused. “Since that event, Smith has repeatedly asked [the woman] about her romantic attachments,” the lawsuit said.

Smith has reportedly told the girls that he’s still attracted to women and has asked them inappropriate, sexual questions, including questions about what a vagina looks like, birth control, breast size, and whether they would get breast reductions. Yet every time the girls have raised concerns to sorority leadership or their peers, they’ve been dismissed as bigots and told to “drop out.”

I know a few things about being in a sorority. In fact, I was a member of the very sorority at the heart of this lawsuit: Kappa Kappa Gamma. And trust me: Dropping out would have been the much simpler choice for these girls. Instead, they chose the much more difficult option of legal action. And they did so because they realized this issue is much bigger than just one sorority house on one college campus. To be sure, it is primarily about a woman’s right to have her own private spaces and opportunities apart from men. But most importantly, this case is about female dignity and the privilege that we as women have to call our unique biology and experiences our own.

The girls’ lawsuit puts it well: “The Fraternity Council has betrayed the central purpose and mission of Kappa Kappa Gamma by conflating the experience of being a woman with the experience of men engaging in behavior generally associated with women,” it reads.

Indeed. Womanhood is not a costume. “Female” is not a choice. Both are unchanging, biological facts that cannot be put on or taken off. By fighting for this truth, the University of Wyoming girls are doing more to advance “sisterhood” than Kappa has ever done.