HELENA, Mont. (AP) — A judge on Wednesday temporarily blocked a Montana law that restricts transgender people's use of bathrooms in public buildings.

The measure, which Republican Gov. Greg Gianforte signed into effect last week, threatened to deprive transgender people of their constitutional right to equal protection under the law, Montana District Court Judge Shane Vannatta ruled. The law prevents people from using restrooms in public buildings that do not align with the sex they were assigned at birth.

The five people who sued over the law were likely to prevail, Vannatta added in his ruling.

The new law "is motivated by animus and supported by no evidence that its restrictions advance its purported purpose to protect women's safety and privacy," Vannatta wrote.

The judge's order will be in effect at least until an April 21 hearing on whether it should continue to be blocked while the lawsuit moves ahead.

Gianforte spokesperson Kaitlin Price said the governor will defend the law "and the privacy and safety of women and girls."

"We're not surprised to see far-left activists run to the courts to stop this common sense law," Price said in an emailed statement. "A man shouldn't be in a women's restroom, shouldn't be in a women's shower room and shouldn't be housed in a women's prison."

The American Civil Liberties Union praised the ruling.

"Today's ruling provides enormous relief to trans Montanans across the state. The state's relentless attacks on trans and Two Spirit people cannot withstand constitutional scrutiny by the courts," said a statement by Alex Rate, ACLU of Montana's legal director.

The law passed this year despite opposition from Democrats who worried it would complicate daily life for two fellow lawmakers who are transgender and nonbinary. They included Rep. Zooey Zephyr, a Missoula Democrat who in 2023 was silenced and sanctioned by her Republican colleagues for comments she made on the House floor.

The law would require 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 based on a person's chromosomes and reproductive biology, despite a recent state court ruling that declared the definitions unconstitutional.

The order wasn't unexpected, bill sponsor Republican Rep. Kerri Seekins-Crowe said in an emailed statement.

"I am thankful that there is a team of Montanans devoted to protecting women's spaces from men who desire to invade them," said Seekins-Crowe.

At least a dozen other states already have variations of bathroom bans on the books, many directed at schools. Even more states, including Montana, have passed laws to ban gender-affirming medical care for transgender children and keep trans girls out of girls sports.

Montana's law allows people to sue a facility if it does not prevent people from using restrooms or changing rooms that do not align with their sex assigned at birth. They can recover nominal damages, generally $1, and the entity could be required to pay the plaintiff's legal fees.