MT SB164

Adds a new category to Montana's child endangerment law making it a criminal offense to knowingly procure or provide gender-affirming medical treatments to children under 16, including surgical procedures, puberty blockers, and hormone therapy (estrogen, testosterone, or androgens)

Violations involving the prohibited gender-affirming treatments constitute a felony punishable by up to 5 years in state prison and fines up to $10,000; if the child suffers serious bodily injury, penalties increase to up to 10 years imprisonment and $25,000 in fines

The prohibition applies to any person regardless of whether they supervise the child's welfare, and specifically targets treatments intended to alter appearance or affirm gender perception inconsistent with biological sex

Effective date is January 1, 2026