A new bill signed into law in Montana, which strictly defines what a man and woman and male and female are — fundamentally, vessels for reproduction — is “essentially the same” as an earlier, failed Republican attempt to erase trans and other non-conforming gender definitions from state law, says out transgender Montana state Rep. Zooey Zephyr (D).

The previous legislation, signed into law in 2023 by Republican Gov. Greg Gianforte, was declared unconstitutional twice, most recently when a judge found it violated the Equal Protection Clause of the Montana Constitution. The 2023 law is still tied up in court.

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Montana tried to mandate that there are only two sexes. A judge called that “a legal fiction.”

Like the earlier version, the new law, S.B. 437, defines sex as based on a person’s “primary sexual anatomy” for the purposes of reproduction, The Montana Free Press reports.

The law defines “gender” as a synonym for sex and says it may not be considered synonymous with a person’s gender identity, experienced gender, gender expression, or gender role.

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Likewise, the term “gender identity,” if used in state law or rules, may not be considered a substitute for the words “sex” or “gender,” the new law says.

Unlike the 2023 law, the new one drops references to sex markers in a person’s chromosomes.

The revised definitions could affect nearly 60 areas of Montana law, from drivers and marriage licenses to representation on state boards and commissions. 

Zephyr said that the new law, like the old version, erases trans, intersex, nonbinary, and Two-Spirit people in Montana “from cradle to grave.”  

“The Republicans design bills like this to do two things,” she said.

One, it functions as part of Republicans’ “continued crusade to make it hard to exist as an LGBTQ person in the state of Montana,” Zephyr said, adding that Republicans are especially trying to “make life hard for trans people.”

Second, the law means to “bring up the boogeyman of trans people as a distraction to the growing resentment of Republican policies in this state and this country,” she said.

Zephyr likened Montana Republicans’ fixation on sex, gender, and trans people to the same derangement Republicans in Congress are suffering at the hands of President Trump in his own anti-trans crusade, which he believes is an electoral winner regardless of any moral arguments he may or may not share with his other anti-trans allies.

Zephyr pointed to Trump’s insistence on adding anti-trans provisions to the completely unrelated SAVE America Act, voter legislation now in the Senate. Even Congressional Republicans couldn’t justify linking trans antipathy to a bill about mail-in voting.

The same legal coalition that challenged the 2023 version of the sex law has already announced its intention to take the new law to court.

First, the coalition will try adding S.B. 437 to their ongoing challenge of the 2023 law, and ask for a preliminary injunction or temporary restraining order to halt it during litigation. If that doesn’t work, they’ll file a new complaint in district court.

S.B. 437’s sponsor, Republican state Sen. Carl Glimm, also wrote the 2023 law which is now tied up in court.

He called his sophomore effort, introduced on the heels of President Trump’s “gender ideology” executive order in February 2025, a “commonsense” measure that was necessary given recent challenges to the gender binary and what he believes is the lack of a reliable state definition of it. The same reasoning underpinned his 2023 bill.

“In our culture, it’s gotten to where that is not clear,” Glimm claimed. “It becomes a fuzzy line for some, so we just need to have clear definitions in law so that it’s clear what we’re talking about when we talk about a male or female.”

He’s prepared, however, to introduce new legislation once again if his latest effort stalls in court.

“The courts,” Glimm said, “are not staying in their lane on this issue.”

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