Lesbian, gay, bisexual, transgender, and queer (LGBTQ) people in the U.S. state of Montana may face some legal challenges not experienced by non-LGBTQ residents.

In 1878, Montana saw one of the earliest recorded sodomy cases in the United States; in Territory v. Mahaffey, a man was convicted of sexual relations with a 14-year-old boy.

[2] A 1989 sex offender registration law further required anyone convicted of sodomy to register with the local chief of police and report any change in address.

[5] Justice James C. Nelson, writing for the 6–1 majority, stated:[2] It cannot seriously be argued that Respondents do not have a subjective or actual expectation of privacy in their sexual activities.

With few exceptions not at issue here, all adults regardless of gender, fully and properly expect that their consensual sexual activities will not be subject to the prying eyes of others or to governmental snooping and regulation.

[11] The Montana Supreme Court recognized a common law same-sex marriage as retroactively valid in Adami v. Nelson on December 10, 2019.

The Montana Supreme Court affirmed this ruling 6–1 on October 7, 2009, setting precedent allowing for future stepparent adoptions by same-sex couples statewide.

[19] On February 23, 2011, the Montana House of Representatives passed, by a 62–37 vote, a bill that would have prohibited local municipalities from adopting anti-discrimination categories not protected in the state law.

[26] In April 2021, Governor Greg Gianforte signed legislation into law granting people the right to discriminate if their religious beliefs are "substantially burdened".

[31] Hate crimes committed on the basis of the victim's sexual orientation or gender identity can be prosecuted in federal courts under the Matthew Shepard and James Byrd Jr.

In December 2024, the Montana Supreme Court invalidated a law that bans transgender individuals from changing sex on a birth certificate or driving licence.

[32] On September 9, 2022, Montana passed a law that prohibits transgender people from changing "identification of sex on birth certificates" unless they provide proof of a data entry error or DNA test result.

[41][42] The ACLU sued in federal and state courts in July 2021, claiming that the term “surgical procedure” was vague and that the rule put transgender individuals at risk of harassment, discrimination and violence.

[43][44] In April 2022, a federal judge agreed that the bill had "no clear legal definitions of what sexual reassignment surgery actually means" and blocked its enforcement.

[33] In 2018, the Montana Family Foundation sought to require transgender people to use public bathrooms corresponding to the gender on their birth certificate, but their initiative failed to collect enough signatures to appear on the November ballot.

[51] On December 11, 2024, the Montana Supreme Court ruled that the preliminary injunction could stand, based on the plaintiffs' claim of a right to privacy.

McKinnon said that Montana’s right to privacy is not the only relevant consideration; the ban is also "fundamentally about the nature of sex and suspect class discrimination as it applies in the equal protection context."

[53] The Montana Legislature passed a law in April 2021 banning transgender individuals from participating in public school sports and athletics.

[58] On April 18, 2023, the first openly trans rep in the state of Montana, Zooey Zephyr, admonished those who supported a bill to prohibit gender-affirming medical and surgical care for transgender minors.

When this remark triggered an objection from Republican majority leader Sue Vinton, Zephyr replied, "The only thing I will say is if you vote 'yes' on this bill and 'yes' on these amendments, I hope the next time there's an invocation when you bow your heads in prayer, you see the blood on your hands.

[60][61] Zephyr stood by her words, and House Minority Leader Kim Abbott defended her, describing the statement as "blatantly disrespectful and the farthest thing imaginable from the 'commitment to civil discourse' that these letter writers demand".

That afternoon, when Zephyr was again denied speaking privileges, prompting all Democratic lawmakers to stand in protest, all but two Republican members of the chamber’s supermajority again voted to uphold Regier’s ruling.

[71] In May 2023, the Governor of Montana signed a bill into law effective immediately passed by the Montana Legislature that explicitly bans drag queens reading books to children in Libraries - the toughest laws so far within the United States on the subject and does not contain legal loopholes (such as the "dressing up as drag of a sexual nature done by individuals", within Tennessee and Florida as examples).

[74][75] A 2022 Public Religion Research Institute (PRRI) opinion poll found that 70% of Montana residents supported same-sex marriage, while 29% opposed it and 1% were unsure.