Twenty-one states led by Democrats sued on Wednesday to block a Department of Health and Human Services plan to bar federal payments from Medicaid and the Children’s Health Insurance Program for gender-transition medication and surgery to transgender adolescents. The new rule, announced last month, is set to go into effect in October. The lawsuit, filed in federal court in Massachusetts, argues that the new rule oversteps the Trump administration’s authority and fails to justify its restrictions.

The suit said the rule violates the law by blocking reimbursements for treatments that some states have determined to be medically necessary. “We will not stand by as the Trump administration oversteps its authority and twists the facts to justify its bad-faith agenda against transgender Americans,” Rob Bonta, the attorney general of California, said in a statement.

The Health and Human Services Department did not immediately respond to a request for comment. In a report issued last year, the federal health department said that the risks of gender transition treatments outweigh any benefits, prioritizing psychotherapy. Most major medical societies, including the American Academy of Pediatrics, continue to support medical gender transition for young people.

The new rule is the latest in a series of efforts by the Trump administration to block health providers from offering the treatments. According to a recent analysis by the Congressional Budget Office, the government spent about $100 million on gender transition treatments for minors over five years from 2019 through 2023. The analysis found that the rate of gender surgery among minors insured by Medicaid was extremely low, at 3.44 per 100,000 among 15- to 17-year-olds.