The Cass Review, published in April 2024, offers an influential example of the degree to which the debate over pediatric sex-transition treatments remains unsettled. See H. Cass, Independent Review of Gender Identity Services for Children and Young People: Final Report (Cass Review). After witnessing a 40-fold increase in the number of referrals to its centralized clinic for sex-transitioning services, the United Kingdom’s National Health Service (NHS) commissioned this report to conduct a “thorough independent review of the use of puberty blockers and cross-sex hormones” to treat children with gender dysphoria. 1 App. 333–334. The report concludes that “we have no good evidence on the long-term outcomes of interventions to manage gender-related distress,” and highlights the lack of reliable evidence to support the use of puberty blockers and cross-sex hormones in treating transgender kids. Cass Review 13, 32–33 (observing “insufficient/inconsistent evidence about the effects of puberty suppression,” and “‘a lack of high-quality research assessing the outcomes of hormone interventions in adolescents with gender dysphoria/incongruence’”); see also ante, at 23. Among other things, the Cass Review determined that the “evidence [the researchers] found did not support th[e] conclusion” that “hormone treatment reduces the elevated risk of death by suicide” among children suffering from gender dysphoria. Cass Review 33; see also id., at 187 (“[T]he evidence does not adequately support the claim that gender-affirming treatment reduces suicide risk”).
This shifting scientific landscape has forced governments to act quickly under conditions of uncertainty. In the months following the Cass Review’s publication, for example, NHS imposed new restrictions on the use of puberty blockers and cross-sex hormones for sex-transition treatments. See ante, at 23. And, just a week after oral argument in this case, the United Kingdom indefinitely banned new prescriptions of puberty blockers to treat children with gender dysphoria, except in clinical trials. See S. Castle, Ban on Puberty Blockers for U. K. Teens Is Settled, N. Y. Times Int’l, Dec. 13, 2024, p. A11. In areas with this much “medical and scientific uncertainty,” courts must afford States “wide discretion.” Gonzales v. Carhart, 550 U. S. 124, 163 (2007).
