Colorado Voters Approve Proposition 135, Banning Gender-Related Surgeries for Minors

Colorado voters have narrowly approved Proposition 135, a ballot measure that bans gender-related surgeries for people under 18 and bars public money from paying for them, making Colorado the first state to enact such a restriction through a citizen initiative.

The Associated Press called the race on Friday, 6 November, with the measure holding about 52 per cent of the vote. At 99 per cent of precincts reporting, the Yes side led with roughly 1.36 million votes to about 1.26 million against, according to figures compiled from NBC News and the Associated Press. The results remain unofficial until the Colorado secretary of state certifies them, which is due by 30 November.

The outcome was one of the closest calls of the 3 November general election. Proposition 135 trailed in the first tallies on election night before moving ahead as later ballots were counted, according to Colorado Politics.

What the measure does

Proposition 135 prohibits healthcare professionals from performing or providing surgeries to anyone under 18 when the purpose is to alter their biological sex characteristics in response to their perception of sex or gender. The ban is defined by the purpose of the procedure rather than by a list of named operations, so how it applies in practice will depend on interpretation.

The measure also bars state and federal funds, including Medicaid reimbursements and private insurance coverage, from paying for the prohibited procedures. That funding restriction would also remove the option for families to seek the surgery out of state using public money.

It carries three exceptions: male circumcision, treatment for medically verifiable disorders of sex development, and treatment for acquired physical or chemical abnormalities.

What it does not cover

The measure does not ban puberty blockers, hormone treatments, counselling or other non-surgical care. Colorado’s official ballot analysis, known as the Blue Book, says it does not restrict non-surgical gender-related care such as social transition or counselling.

That distinction matters because the procedures at issue are rare. Colorado’s three large paediatric surgical providers — Children’s Hospital Colorado, Rocky Mountain Children’s and Denver Health — reported that they do not perform gender- or sex-based surgeries on transgender patients younger than 18, according to the state voter guide. A 2024 study of insurance claims covering nearly 23 million minors, published in JAMA Network Open, identified 85 gender-affirming surgical procedures among patients under 18 in 2019, 82 of them chest-related, and none among children aged 12 or younger.

A first for ballot measures

Proposition 135 was a citizen-initiated state statute, which meant it needed only a simple majority to pass. It qualified for the ballot in March after supporters submitted nearly 165,000 petition signatures.

The campaign was led by Erin Lee, and the group behind it, Protect Kids Colorado, declared victory on Wednesday evening as the lead held. About $4.63 million was raised for and against the initiative as of October, according to Ballotpedia.

Colorado voters approved a companion measure on the same ballot. Proposition 134, which requires students to take part in school and collegiate sports teams matching their sex as defined by biological reproductive systems, also passed, with nearly 53 per cent of the vote. Washington voters approved a separate ballot measure this month barring transgender girls from girls’ school sports, while California voters rejected Proposition 40, a one-time tax on billionaires.

Reaction and what happens next

Democratic Governor-elect Phil Weiser, who takes office in January, told a post-election news conference at the State Capitol in Denver on Wednesday, 4 November, that both measures deserve further examination. He said Proposition 134 and Proposition 135 will need “a long, hard look” and that adjustments may be necessary.

By their own terms, the measures take effect on 1 January 2027. The state legislature convenes on 11 January, giving lawmakers an early chance to revisit the details. Opponents of the measure, including LGBTQ rights advocates, have argued that it targets care that is already uncommon and that the state’s ballot analysis acknowledged some surgeries involving patients who are not transgender could also be affected, depending on how the restrictions are interpreted.

For now, the result stands as a narrow but clear verdict from voters in a state long associated with protections against discrimination — and as a signal that ballot initiatives, rather than legislatures, may become the next front in the national fight over gender-related care for minors.

Frequently Asked Questions

What does Colorado Proposition 135 ban?

It bans surgeries on people under 18 when the purpose is to alter their sex characteristics in response to their perception of sex or gender, and it bars state and federal funds, Medicaid and insurance from paying for those procedures.

Does it ban puberty blockers or hormone therapy?

No. The measure covers surgery only. Puberty blockers, hormone treatments and counselling are not directly prohibited by its restrictions.

When does the measure take effect?

By its own terms, it takes effect on 1 January 2027, after the vote is certified — certification is due by 30 November — and the governor formally proclaims the result.