Montana officials at the state's Department of Public Health and Human Services made a permanent rule on Friday that not blocks trans people from changing their gender on their birth certificates.
The rule went into effect on Saturday, according to CNN.
Now, birth certificates in Montana can only be changed if something was incorrect on it due to "a scrivener's error or a data entry error" or if"the sex of the individual was misidentified on the original certificate and the department receives a correction affidavit and supporting documents, ... including a copy of the results of chromosomal, molecular, karyotypic, DNA, or genetic testing that identify the sex of the individual."
It also states that sex is "immutable," and described gender as a "social construct" that changes, the Associated Press reports.
The rule change by GOP Gov. Greg Gianforte's administration was made less than a week before the state will face LGBTQ+ rights groups in court over the legality of another similar rule made by health officials in May. In that case, the American Civil Liberties Union of Montana has requested state Judge Michael Moses toss out that rule.
Earlier this year, Moses temporarily blocked the rule that created challenges for trans people to change their birth certificates.
The challenges posed included individuals being required to have gender-confirmation surgery before changing their birth certificate.
The state government's new law goes beyond that, blocking changes even if a person has surgery confirming their gender.
Plaintiffs represented by the ACLU of Montana have explained that denying them the ability to change their gender on their birth certificates opens them up to discrimination, embarrassment, and violence.
Following Friday's rule change, ACLU attorney Akilah Lane told the AP that it was "further evidence of the state's non-compliance" with Moses' previous order back in April.
In May, the ACLU of Montana said the state hadn't followed Moses' injunction over the previous rule change.
"We have continued to be patient in allowing the State time to comply with the court-ordered preliminary injunction," said a statement issued by the ACLU of Montana, the ACLU Foundation LGBTQ & HIV Project, and the law firm of Nixon Peabody, all of which were involved in the case. "However, close to one month has passed and the State's willful indifference to the court order is inexcusable. The procedure in place prior to the passage of SB 280 was simple and efficient and administered without incident for years.
"The fact that the State refuses to revert to the previous processes evidences its lack of respect for the judiciary and utter disregard for the transgender Montanans who seek to have a birth certificate that accurately indicates what they know their sex to be."
Montana's new rule is the latest effort by conservatives across the U.S. to restrict trans people's rights. Tennessee and West Virginia have similar rules. Oklahoma passed a law in April that prohibits nonbinary gender markers on birth certificates.
The AP notes that bans in Idaho and Ohio were struck down two years ago.