Hawzah News Agency – Oklahoma Gov. Kevin Stitt (R) has signed a bill forbidding the use of nonbinary gender markers on state birth certificates.

People who are nonbinary do not identify with traditional male or female genders.

Experts say it's the first ban of its kind written into law in the nation.

The new law made permanent an executive order from Stitt who last year blocked the Oklahoma State Department of Health from issuing nonbinary birth certificates. It went into effect immediately when the governor signed it on Tuesday.

The bill followed a flap last year over the Department of Health's agreement in a civil case allowing a nonbinary option. The birth certificate, in that case, was issued to an Oklahoma-born Oregon resident who sued after the agency initially refused the request.

Lambda Legal, an LGBT-focused civil rights group, challenged the executive order in federal court, but the state has not yet responded.

"We must stand up and put a stop to this nonsense regarding biological sex," Sen. Michael Bergstrom (R-Adair), the Senate sponsor of the bill said in a statement. "It's not a complicated issue – biologically, you're either a male or female. There should be no other option to choose from on a birth certificate."

Fifteen states and the District of Columbia specifically allow a gender designation outside of male or female. Vermont will become the next state to allow the designation when its new statute takes effect on July 1.