Transgender people in Montana can no longer use bathrooms in public buildings that do not align with their sex assigned at birth after Republican Gov. Greg Gianforte signed new restrictions into law Thursday.

The law requires public buildings including the state Capitol, schools, jails, prisons, libraries and state-funded domestic violence shelters to provide separate spaces for men and women.

It defines the sexes in state law based on a person’s chromosomes and reproductive biology, even as a district court ruling earlier this year declared the definitions unconstitutional.

The new law also declares that there are only two sexes, male and female, going against a judge’s 2024 ruling that struck down that same definition.

Under the law, transgender people cannot use public restrooms, changing rooms and sleeping areas that align with their gender identity. The law does not explain how people in charge of public facilities should verify someone’s sex.

Rep. Kerri Seekins-Crowe, the Republican sponsor, said it was not meant to be exclusionary but to preserve safe spaces for women.

A transgender man who has undergone a medical transition to develop more masculine features such as facial hair, muscle definition and a deeper voice is now required by law to use the women’s restroom.

Republican lawmakers swiftly approved the measure despite vocal opposition from Democrats who worried it would complicate daily life for two fellow lawmakers who are transgender and nonbinary. Among them was Rep. Zooey Zephyr, the Missoula Democrat who was silenced and sanctioned by her Republican colleagues in 2023 for comments she made on the House floor.

Zephyr warned it would embolden some to police another person’s gender in public, which she said could create hostile situations for everyone.

The law allows people to sue a facility for not preventing transgender people from using a certain restroom or changing room. They can recover nominal damages, generally $1, and the entity could be required to pay the plaintiff’s legal fees.