California doctors would be barred from treating or performing surgery on children born with genitals that don’t fit a single gender or are otherwise atypical unless it’s medically necessary or the child consents, under a bill unveiled Monday.

It’s the latest effort by state legislators to give minors more control over their bodies and gender identities.

“The fundamental premise of the legislation is that people should make decisions about their own bodies,” said Democratic Sen. Scott Wiener of San Francisco, the bill’s sponsor. “In California we strongly believe that people are who they are and that we shouldn’t be telling people who they are supposed to be.”

Doctors, though, said the bill may go too far in restricting how they can treat patients. The California Medical Association hasn’t taken a formal position on the bill but has “very serious concerns” that include the bill’s lack of a definition around when a minor is old enough to consent.

“Our concern is that the approach in this bill may be being overly prescriptive and not give families and medical professionals the ability to take the specifics of each case into account,” Janus Norman, senior vice president for governmental relations, said in a statement.

The bill focuses on intersex minors, defined as someone who is born with atypical physical sex characteristics, which could include genitals or internal organs that don’t conform to a single gender.

InterACT, a nonprofit working to expand rights for intersex youth, estimates just less than 2 percent of the U.S. population has some type of intersex characteristic. That includes a broad range of characteristics ranging from an enlarged clitoris or a misplaced urethra opening on the penis to genitalia that don’t clearly match one gender.

About one in 2,000 babies are estimated to have visible genital differences putting them at risk of early surgery, said Kimberly Zieselman, the group’s executive director. Unnecessary surgeries could mistakenly identify a child’s preferred gender or, in cases unrelated to gender, leave scarring or affect future fertility, she said.

“It’s not just a gender issue,” Zieselman said. “There are a lot of other harms that happen to many intersex people as a result of the interventions that are psychological and physical.”

Under Wiener’s bill, doctors and parents wouldn’t be allowed to move ahead with treatment or surgery unless it is medically necessary, such as something that would prevent a child from urinating. Treatments or surgeries outlined in the bill include removal or reduction of the clitoris or removal of the ovaries or testis. It could also bar additional procedures not specifically outlined in the bill.

If a doctor considers surgery medically necessary, he or she would need parental consent. If the treatment isn’t necessary, the doctor and parents would have to wait until the child is old enough to give consent and obtain approval for any procedures.

The bill doesn’t define when a minor can give consent. It is intentionally vague, Wiener’s office said, and would rely on guidelines already in state law around when a child is able to consent on certain medical procedures. The California Medical Association cited that as a reason for concern.

“There are also serious questions about the nature and legal threshold for informed consent as used in the bill,” Norman said.

Under current medical guidelines, doctors form teams of experts, including psychologists or urologists, to evaluate each individual circumstance. Considering the physical and emotional health of the future child is a key piece of the evaluation, Norman said.

Under the bill, doctors could not be criminally held responsible if they violate the law but could be disciplined by the state’s medical board.

Wiener said his office will work with the medical association if it has constructive feedback.