A controversial discussion about gender identity and legal recognition in Montana has been rekindled by a new law enacted by the legislature that aims to define a person’s legal sex as exclusively male or female based on biological traits.
After passing its third reading in the House by a vote of 55 to 44, Senate Bill 437—sponsored by Senator Carl Grimm, R-Kila—is now on its way to Governor Greg Gianforte’s desk for final approval.
The measure would create chromosomally based legal definitions of sex if it were to become law. People with XX chromosomes would be considered female, and people with XY chromosomes would be considered male, as per the law.
For people who are born with congenital disorders that impact chromosomal or anatomical development, the bill has a few limited exceptions. The new definitions, however, would be applicable to a variety of government-issued records and systems, such as driver’s licenses and birth certificates, for the general public.
SB 437’s proponents contend that the bill provides the legal framework required to guarantee uniformity and clarity in public documents. During a floor discussion, Senator Grimm stated, “This legislation is about aligning our legal definitions with scientific reality. We’re not targeting anyone—we’re just making sure the law reflects biological truth.”
Critics, however, vehemently disagree. Many Democratic lawmakers, civil rights organizations, and LGBTQ+ supporters have opposed the bill, claiming it is an outright assault on Montanans who identify as transgender or non-binary.
They contend that using chromosomes alone to define gender erases the identities of those who identify as a gender other than the one assigned at birth and may result in more exclusion and discrimination.
“This bill doesn’t just define biology—it defines who gets to be seen and recognized by their government,” stated Democratic Representative Zooey Zephyr, one of Montana’s first lawmakers to be openly transgender. “It sends a message to transgender Montanans that their lives and identities are invalid.”
Montana has sought to enact laws defining gender roles before. In 2023, Senate Bill 458 was passed, which was a similar measure.
But in February 2025, a Missoula district court judge declared the statute illegal, claiming it infringed upon the state constitution’s protections for transgender people. An appeal of that decision is presently pending.
Lawmakers reworded SB 437 in the hopes that it would pass legal muster in spite of the court’s ruling on SB 458. Since Governor Gianforte has not yet stated whether he will sign the bill into law, all eyes are currently on him.
Source: ktvh
