Bill redefining sex signed nearly a year after it passed

Gov. Greg Gianforte last week signed the final bill passed during the 2025 legislative session defining sex in state law, likely spawning a protracted legal fight.

Senate Bill 437, which defines sex as only male or female, was signed on March 24, 2026, but sat on Republican House Speaker Brandon Ler’s desk for nearly a year. Senate President Matt Regier, R-Kalispell, signed the bill on April 21, 2025.

The bill is similar to 2023 Senate Bill 458, which also defined sex and was challenged in court. The earlier legislation was thrown out in the midst of the 2025 session, and Missoula County District Court Judge Leslie Halligan signaled at the time any similar bills would also likely be found unconstitutional.

But Ler said Monday that Republicans were deliberate about protecting the law from legal challenges, and the legislation should stand on its own.

“We … believe the law should be evaluated on its own merits, not folded into broader challenges, and we are prepared to defend it,” Ler said in a statement.

State Republicans have accused Montana judges of playing politics, which is why they sought to hold the bill long after the House and Senate passed it into law.

Ler has said that voters sent politicians to Helena to make laws, “not to let activist judges tear it down the moment the ink dries.” Sen. Carl Glimm, R-Kila, introduced the legislation in both 2023 and 2025.

Last year, Upper Seven Law Firm informed the state it would add claims against SB 437 to an existing case against SB 458. ACLU of Montana also filed a case against SB 458 and won, and the organization did not immediately respond to a request for comment.

“From the beginning, we took a deliberate approach to the timing of SB 437 to ensure it was as well positioned as possible as it moves forward and faces potential legal challenges,” Ler said in a statement on Monday. “That process has run its course, and this is the appropriate point for the bill to move forward.”

Multiple bills passed by the Montana Legislature have targeted the state’s transgender and intersex community, and last year a Montana ACLU lobbyist testified SB 437 would essentially “force transgender people to live a lie.”

Glimm’s legislation changes the definition across a broad swath of Montana laws, including those dealing with education, insurance and even marriage.

Sponsors of the legislation, brought by state Republicans,  as well as the governor, have said they’re bringing the laws in an effort to protect women.

“This law codifies the long-recognized, commonsense, immutable, biologically-based definition of sex, male and female, while protecting people born intersex and not infringing on transgender individuals’ ability to identify with whatever gender, but not sex, they wish,” Gianforte said in a statement to the Daily Montanan.

Glimm’s legislation would force intersex and transgender people to identify as the sex they were assigned to when born.

A plaintiff in the lawsuit against SB 458 had an XY pattern, which under both that bill and Glimm’s 2025 legislation, would identify them as male. That plaintiff, however, has female genitalia, identifies as a woman and would be forced to identify as a male on her wedding license.

About one in 100 people are intersex, according to Planned Parenthood, which can include someone whose genitals do not correspond with their internal hormones or sex organs.