The governor of the US state of Texas signed a bill banning the provision of sex reassignment treatments to minors on Friday, making the state the largest of 20 to outlaw such treatments.

Republican lawmakers across the country are pushing similar bills, saying they don’t trust the view of major medical associations that have announced they support the provision of transgender treatment when it’s deemed medically necessary, saying it could even save the lives of transgender teenagers.

Texas, the second most populous state in the US, is home to an estimated 29,800 transgender teenagers between the ages of 13 and 17, according to UCLA’s Williams Institute.

The civil rights group ACLU and other organizations have vowed to challenge the new law in Texas, as they have done elsewhere in the US.

Texas lawmakers “are determined to join a growing group of states intent on endangering the health and lives of transgender youth in direct opposition to a wealth of scientific and medical evidence,” the ACLU charged when the bill had been adopted by both houses of the Texas Congress.

This law provides exemptions for minors who started gender transition treatments before June 1 and for those who have had at least 12 psychotherapy sessions over a period of at least six months. But even they “should gradually come off the medication.”

Supporters of the law believe the government should step in, against the wishes of parents and doctors, because they fear such treatments will cause undue harm to young people and believe minors are incapable of making such decisions.

Organizations such as the American Medical Association, the American Psychological Association and the American Academy of Pediatrics oppose the legislation.

Republicans have proposed more than 500 bills so far this year that affect the LGBTQ+ community, according to the Human Rights Campaign, an organization that supports the rights of LGBTQ+ people. This is a clear increase compared to the 315 bills proposed in 2022, of which 29 were adopted.