Oklahoma Gov. Kevin Stitt has signed a bill requiring public school students to use only the bathroom of the sex listed on their birth certificate.
The bill was overwhelmingly approved last week by the Republican-controlled Legislature.
It was proposed after Stillwater Public Schools declined to change a policy that allows students to use the bathroom that agrees with their gender identity.
Supporters say the bill is about common sense and note that it allows for separate, gender-neutral bathrooms.
Opponents say it unfairly targets transgender students and promised to challenge the measure in court.