Mont. Code Ann. § 27-2-219

27-2-219 . (Effective October 1, 2026) Tort actions -- gender transition treatment for minors. (1) An action brought by a person for damages for injuries suffered from gender transition treatment the person received as a minor must be commenced by the date the person reaches 25 years of age or within 2 years from the time of discovery by the person of both the injury and the causal relationship between the gender transition treatment and the injury, whichever occurs later, except that an action may not be commenced after the person reaches 30 years of age.

(2) An action brought pursuant to 50-4-1405 for injuries suffered from gender transition treatment the person received as a minor must be brought within the timeframes specified in this section.

(3) For the purposes of this section, "gender transition treatment" means the following medical treatments provided:

(a) to a female minor to address the minor's perception that her gender or sex is not female:

(i) surgical procedures, including a vaginectomy, hysterectomy, oophorectomy, ovariectomy, reconstruction of the urethra, metoidioplasty, phalloplasty, scrotoplasty, implantation of erection or testicular protheses, subcutaneous mastectomy, voice surgery, and pectoral implants;

(ii) supraphysiologic doses of testosterone or other androgens; or

(iii) puberty blockers, such as GnRH agonists or other synthetic drugs that suppress the production of estrogen and progesterone to delay or suppress pubertal development in female minors; and

(b) to a male minor to address the minor's perception that his gender or sex is not male:

(i) surgical procedures, including a penectomy, orchiectomy, vaginoplasty, clitoroplasty, vulvoplasty, augmentation mammoplasty, facial feminization surgery, voice surgery, thyroid cartilage reduction, and gluteal augmentation;

(ii) supraphysiologic doses of estrogen; or

(iii) puberty blockers, such as GnRH agonists or other synthetic drugs that suppress the production of testosterone to delay or suppress pubertal development in male minors.