MontanaSB 43769th Legislature, Regular Session (2025)SenateWALLET

Revise definition of sex in Montana law

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Bill Overview

Analyzed Economic Effects

22 provisions identified: 6 benefits, 2 costs, 14 mixed.

Same-sex marriage barred in Montana

The law prohibits marriages between persons the law defines as the same sex. Clerks do not issue licenses to those couples. This blocks access to state marriage status and related benefits in Montana.

Child support and parentage rules updated

For child support, a parent is a father or mother as the law defines. Support filings must list a child’s sex when known, and the state registry records the sex of each parent and child. If you have sex with someone the law deems the opposite sex, you are presumed to know pregnancy can result. These rules can change who must pay support and who can receive it.

State workers: leave and fair pay

Permanent state employees who are birth fathers or who adopt may use up to 15 working days of sick leave right after birth or placement. The Department of Administration must remove sex‑biased factors when setting job classes and pay plans. This aims to make state pay more fair across job groups.

School rules on teams and pronouns

Schools and colleges must label each team as male, female, or coed using the law’s sex definition. Teams for girls/women cannot include students of the male sex. Charter and community choice schools may be formed to serve one gender. For school trips, parents must be told and must consent before a child shares a room with the opposite sex. School boards must require written parent consent before a student uses pronouns that do not match their sex, and staff cannot be forced to use those pronouns.

Statewide definition of sex and gender

The law sets one statewide definition of sex as male or female based on reproductive anatomy and gametes. It defines male, female, man, woman, father, mother, and gender. It says gender means sex in Montana law and not gender identity. These definitions now apply across Montana statutes.

Insurance uses new sex definitions

Montana insurance law now uses the Act’s meanings for male, female, sex, and gender. Insurers must use these definitions when they decide eligibility, underwriting, and policy terms.

Who gets retirement if none named

If no named beneficiary survives, the order for paying state retirement benefits still applies. The terms father and mother now use the law’s definitions when deciding who gets paid.

Hospitals and clinics: patient rights

Public hospital districts must admit people without regard to sex under the law’s definition. A mother, as defined, may breastfeed anywhere she and her child may be. Mental health patients have supervised chances to interact with the opposite sex unless a clinician orders otherwise in writing. For certain alcohol and drug services, a minor means anyone under 18.

Workers’ comp relative rule for small businesses

If you are a corporate officer who meets the ownership rules, a parent who is a mother or father (as defined) can count as a qualifying relative for a workers’ compensation exemption. This can lower coverage costs for eligible small businesses.

Justice and safety records use set sex data

Sex and gender terms in child‑sexual‑abuse laws and inmate rules use the law’s definitions. County attorneys must include a victim’s age and gender in child‑sex‑abuse certifications. The Missing Indigenous Persons Task Force and Looping In Native Communities network must report gender and age using that meaning. Mental‑health commitment petitions list a respondent’s sex when known. Youth means under 18, regardless of sex. Sentencing stays gender‑neutral using the law’s definition.

Education funds and hiring program rules

The Department of Corrections sends quality educator payments to Pine Hills and the facility that serves female youth, using the law’s sex definition. Employers who discriminate based on sex (as defined) cannot participate in the named employment program.

Prenatal blood test at first visit

Every person who meets the law’s definition of female and seeks prenatal care must give a blood sample at the first prenatal visit. The provider must collect and send it to a lab.

Health care rules use new sex terms

Health care facilities must apply nondiscrimination rules using the law’s definition of sex. Family‑practice care is defined without limits by a patient’s sex using that meaning. Reproductive statutes use the law’s definition of female. Residents in habilitation facilities have a right, with supervision, to interact with the opposite sex as defined; any limit needs a written order renewed monthly.

IDs and vital records use new sex

Marriage license applications must list each party’s sex using the law’s definition. Marriage declarations must include the father’s name and the mother’s maiden name. Birth and other vital records use the law’s meanings for father, mother, and sex. Driver’s license and ID applications list your full legal name, date of birth, sex, address, and a brief description. If you were licensed in another state in the last 10 years, the state requests your prior driving record.

Veterans’ homes may consider sex

When placing residents in a Montana veterans’ home, staff may consider the person’s gender as the law defines it. This only applies to matching available living spaces.

Accessible restrooms in building changes

When a public building is altered, the path of travel must include accessible restrooms for each sex as defined, or a single unisex restroom if the building code allows. This applies when the alteration affects a primary function area and as part of prioritized access upgrades.

Tourist and highway signs: follow laws

To get on tourist or specific information signs, a business must promise to follow public‑accommodations laws, including nondiscrimination by sex as defined. Breaking those laws makes the business lose sign eligibility. Businesses must also meet licensing and operating standards, like posted hours where required.

Boards and commissions reflect gender balance

Some public and nonprofit boards must consider gender, as the law defines it, when choosing members. Foundations getting public assets must reflect their communities, including gender. Community corrections boards should be gender‑balanced when possible. The Commission on Community Service should be balanced by race, ethnicity, age, gender, and disability.

Civil rights rules use one sex definition

Montana’s anti‑discrimination laws now use one statewide definition of sex. Employers, landlords, and service providers must follow that meaning. Qualified private schools and Arts Council grantees must agree not to discriminate based on sex using that definition. Wrongful‑discharge cases that rely on anti‑discrimination laws use the same meaning. The law also repeals a prior general‑definitions section to align terms.

Elections and party roles use new sex rules

Ballot pamphlet arguments that shame groups for race, religion, or the law’s definition of sex are rejected with required approvals. Candidates pledge not to appeal to prejudice based on race, sex, creed, or national origin. Each party must choose one precinct committee representative of each sex. County committees must pick one state member of each gender, and the chair and vice chair cannot be the same gender.

Family terms in probate, veterans, and boating

Several laws now use father and mother as the bill defines. Probate and similar terms that mention sex follow the new meaning. Veterans’ preference rules define father, mother, and military duty. In boat‑owner liability cases, the listed family presumption includes father and mother as defined.

Organ donor data sharing and costs

If you choose to be an organ donor on your Montana driver’s license, the Department of Justice sends your license information, including sex as defined, to the federal organ procurement group. The department may charge actual costs for the first electronic transfer, but later transfers are free. Organ and tissue procurement groups must pay reasonable costs to create and maintain the donor registry through a special state account.

Sponsors & Cosponsors

Sponsor

Carl Glimm
Republican • Senate

Cosponsors

Lee Deming
Republican • House

Roll Call Votes

All Roll Calls

Yes: 204 • No: 142

House vote • 4/11/2025

Do Concur

Yes: 56 • No: 44

House vote • 4/11/2025

Do Concur

Yes: 55 • No: 44

Senate vote • 3/6/2025

Do Pass

Yes: 31 • No: 18

Senate vote • 3/5/2025

AMD-SB0437.001.002 Glimm D/PASS

Yes: 30 • No: 18