MONTGOMERY, Ala. — The U.S. Department of Justice on Friday challenged an Alabama law making it a felony for doctors to treat transgender people under age 19 with puberty-blockers and hormones to help affirm their new gender identity.

The Justice Department filed a motion seeking to intervene in an ongoing lawsuit challenging the law as unconstitutional and seeking to block it from taking effect on May 8.

The action comes after the department sent a letter to all 50 state attorneys general warning that blocking transgender and nonbinary youth from receiving gender-affirming care could be an infringement of federal constitutional protections.

Doctors and others would face up to 10 years in prison for violating the Alabama law. Trans kids and parents have said Alabama is trying to ban what they consider necessary, and sometimes life-saving care for them.

“The law discriminates against transgender minors by unjustifiably denying them access to certain forms of medically necessary care,” the complaint states. “As a result of S.B. 184, medical professionals, parents, and minors old enough to make their own medical decisions are forced to choose between forgoing medically necessary procedures and treatments or facing criminal prosecution.”

Alabama Republicans who supported the law have maintained it is needed to protect children.

Alabama Attorney General Steve Marshall said Friday that the “Biden administration has chosen to prioritize leftist politics at the expense of Alabama’s children.”

“As we will show in this case, DOJ’s assertion that these treatments are ‘medically necessary’ is ideologically-driven disinformation. The science and common sense are on Alabama’s side. We will win this fight to protect our children,” Marshall said in a statement.

Four families with transgender children, two doctors and a member of the clergy filed a lawsuit challenging the Alabama law as an unconstitutional violation of equal protection and free speech rights and an intrusion into parental decisions. U.S. District Judge Liles Burke has scheduled a May 5 hearing on a request for a restraining order or preliminary injunction to stop Alabama officials from enforcing the law while the court challenge goes forward.

Sarah Warbelow, legal director for the Human Rights Campaign, a LGBTQ advocacy group, said they are “encouraged to see the Department of Justice weigh in on this law that so severely interferes in the lives of Alabama families.”

“Parents want to do what’s best for their children, but SB 184 strips some Alabama parents of that ability by imposing criminal penalties for providing critically important and established medical care for their transgender children,” Warbelow said in a statement.

Alabama is among several states with Republican-controlled legislatures that have advanced bills regarding transgender youth and LGBTQ issues.

The Alabama law is the furthest reaching and the first to criminalize the treatments. Texas Gov. Greg Abbott had ordered the state’s child welfare agency to investigate as abuse reports of gender-confirming care for kids. Arkansas also banned gender-affirming medications, but that law has been blocked from taking effect.