Los Angeles (CNN) -- Transgender students in California would be able to choose which school bathrooms and locker rooms to use and which sport teams to join based on their gender identity under a measure approved this week by the California Legislature.
The proposal now awaits the signature of Gov. Jerry Brown, whose office has declined to comment on whether he will sign it.
The proposal would be the first state law in the nation that specifically requires equal access to public school facilities and activities based on gender identity, though some states have general policies to the same effect, said Shannon Price Minter, legal director of the National Center for Lesbian Rights, one of several groups backing the legislation.
But enactment of the measure would "simply mean that California will be catching up with other states that already have enacted regulations based on a general prohibition of gender identity discrimination in schools," Minter told CNN.
"Our view is that California's existing law should already require schools to provide transgender students with equal access to facilities and activities, but in practice, many schools are not complying with that requirement and will not do so unless the Legislature provides specific guidance on this issue," Minter said.
Though California prohibits discrimination in education, transgender students "are often still unfairly excluded from physical education, athletic teams, and other school activities and facilities because of who they are," according to a statement by the center and other groups supporting the measure.
The California Senate approved the proposal on Wednesday, 21-9. It had been earlier approved by the Assembly in early May.
State Senate Republicans largely opposed the measure during debate, as broadcast by CNN affiliate KCRA.
"There are youthful sex offenders," said state Sen. Jim Nielsen. "I guarantee there would be those who would use this opportunity."
"It's going to be problem with implementation," said Sen. Jean Fuller.
The proposed law would require that a pupil "be permitted to participate in sex-segregated school programs and activities, including athletic teams and competitions, and use facilities consistent with his or her gender identity, irrespective of the gender listed on the pupil's records," the legislation says.
Ashton Lee, a 16-year-old transgender boy from of Manteca, California, testified before the Senate Education Committee last month. Lee wants to play high school football.
"I just want to be treated the same as all the other boys, but my school forces me to take P.E. in a class of all girls and live as someone I'm not," Lee said in a statement. "I can't learn and succeed when every day in that class leaves me feeling isolated and alone."
The Los Angeles Unified School District, the nation's second largest, implemented a policy in 2005 that's "nearly identical" to the legislative proposal now awaiting the governor's signature, advocacy groups said.
"We've worked closely with students and families to ensure that our policies related to gender identity are successful, welcomed by students, and supported by parents," Judy Chiasson, the district's program coordinator for human relations, diversity and equity, said in a statement.