On Tuesday, families of transgender children filed a lawsuit in federal court, seeking to block President Donald Trump’s directive that halts all federal funding or support for healthcare aiding gender transitions for individuals under 19.

The families, represented by Lambda Legal and the American Civil Liberties Union, argue in the lawsuit filed in Maryland federal court that the order discriminates against transgender people and exceeds Trump’s presidential powers.

The White House did not respond to a request for comment immediately.

According to the lawsuit, hospitals across the U.S. have already started canceling gender transition treatment appointments due to the order. The plaintiffs allege that in recent days, appointments at Children’s National Hospital in Washington, D.C., NYU Langone in New York, Boston Children’s Hospital, and Children’s Hospital of Richmond in Virginia were canceled. These hospitals are not part of the lawsuit.

In the January 28 order, Trump, a Republican, stated that it is the policy of the U.S. government to not fund, promote, or support the “transition” of a child from one sex to another and emphasized enforcing laws prohibiting such procedures, which he described as destructive and life-altering.

The specifics of how the order will be enforced and its scope remain unclear.

The order instructed the U.S. Department of Health and Human Services to “take all appropriate actions” to end “the chemical and surgical mutilation of children.” This could involve imposing conditions on healthcare providers that receive federal funds, which is most hospitals.

The lawsuit described the order as part of a broader attack by President Trump on “gender ideology” and transgender individuals.

This followed previous executive actions by Trump, including a ban on transgender people in the military and a policy stating the government would not recognize gender identity beyond an individual’s biological sex.

The military ban has already been challenged by transgender rights organizations, while the policy regarding gender identity recognition has been contested in two lawsuits by transgender women in federal prisons, one of whom won a temporary restraining order preventing her transfer to a men’s prison.

The treatments affected by the order include puberty blockers, hormones, and surgeries provided to individuals under 19 for gender transition, often referred to as gender-affirming care.

In more than half of U.S. states, Republicans have passed laws or policies banning gender-affirming care for minors, though some of these laws have been blocked or reversed in court. A challenge to Tennessee’s ban is currently before the U.S. Supreme Court, which has yet to rule on its potential national impact.

The administration of former President Joe Biden, a Democrat, supported access to puberty blockers and hormones for transgender minors, though it did not support surgery. Biden’s administration also passed a rule prohibiting discrimination against transgender individuals in healthcare, though a judge blocked it last year.

The American Academy of Pediatrics has argued that gender-affirming care is crucial for preventing suicide and improving mental health.

Some health organizations in other countries have been more cautious, with the European Academy of Paediatrics calling for more research, and a government-sponsored review in England concluding that the evidence supporting youth gender care is weak. — Reuters