The U.S. Supreme Court said Monday that it will hear arguments on the constitutionality of state bans on gender-affirming care for transgender minors.

The issue has emerged as a big one in the past few years. While transgender people have gained more visibility and acceptance in many respects, half the states have pushed back with laws banning certain health care services for transgender kids.

Understanding Gender-Affirming Care

Gender-affirming care includes a range of medical and mental health services to support a person’s gender identity, including when it’s different from the sex they were assigned at birth.

The services are offered to treat gender dysphoria, the unease a person may have because their assigned gender and gender identity don’t match. The condition has been linked to depression and suicidal thoughts.

Gender-affirming care encompasses counseling and treatment with medications that block puberty, and hormone therapy to produce physical changes. Those for transgender men cause periods to stop, increase facial and body hair, and deepen voices, among others. The hormones used by transgender women can have effects such as slowing growth of body and facial hair and increasing breast growth.

Gender-affirming care can also include surgery, including operations to transform genitals and chests. These surgeries are rarely offered to minors.

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State Laws on Gender-Affirming Care

Over the past three years, 26 Republican-controlled states have passed laws restricting gender-affirming care for minors. Most of the laws ban puberty blockers, hormone treatment and surgery for those under 18. Some include provisions that allow those already receiving treatment to continue.

The laws also make exceptions for gender-affirming treatments that are not part of a gender transition, such as medications to stop breast growth in boys and excessive facial hair in girls.

One of the laws — in Arkansas — was nixed by a federal court and is not being enforced.

Meanwhile, at least 14 Democratic-controlled states have adopted laws intended to protect access to gender-affirming care.

The gender-affirming care legislation is a major part of a broader set of laws and policies that has emerged in Republican-controlled states that rein in rights of transgender people. Other policies, adopted in the name of protecting women and girls, bar transgender people from school bathrooms and sports competitions that align with their gender.

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Court Decisions on Gender-Affirming Care

Most of the bans have faced court challenges, and most are not very far along in the legal pipeline yet.

The law in Arkansas is the only one to have been struck down entirely, but the state has asked a federal appeals court to reverse that ruling.

The 6th U.S. Circuit Court of Appeals, one step below the Supreme Court, last year ruled that Kentucky and Tennessee can continue to enforce their bans amid legal challenges. The high court has agreed to hear the Tennessee case in the term that starts later this year.

The U.S. Supreme Court in April ruled that Idaho can enforce its ban while litigation over it proceeds. A lower court had put it on hold.

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Medical Community’s View on Gender-Affirming Care

Every major U.S. medical group, including the American Academy of Pediatrics and the American Medical Association, has opposed the bans and said that gender-affirming treatments can be medically necessary and are supported by evidence.

But around the world, medical experts and government health officials are not in lockstep. Some European countries in recent years have warned about overdiagnosis of gender dysphoria.

In England, the state-funded National Health Service commissioned a review of gender identity services for children and adolescents, appointing retired pediatrician Dr. Hilary Cass to lead the effort. The final version of the Cass Review, published in April, found “no good evidence on the long-term outcomes of interventions to manage gender-related distress.”

England’s health service stopped prescribing puberty blockers to children with gender dysphoria outside of a research setting, following recommendations from Cass’ interim report.

The World Professional Association for Transgender Health and its U.S. affiliate issued a statement in May saying they’re deeply concerned about the process, content and consequences of the review, saying it “deprives young trans and gender diverse people of the high-quality care they deserve and causes immense distress and harm to both young patients and their families.”