On Thursday, a federal court upheld a California law making it illegal for therapists to persuade minors to change their sexual orientation. Opponents challenged it on free speech grounds.
Senator Ted Lieu said his law shields young people from the controversial practice of gay conversion therapy, which he said can be psychologically harmful.
"These psychiatrists and psychologists and mental health professionals are practicing a form of quackery that has been rejected by every major medical organization," Lieu said.
But Brad Dacus of the Pacific Justice Institute said the law prevents therapists from treating patients in the way they think is best.
"When you have a young person who has these feelings and wants to reconcile those feelings in a way that's in accordance with his faith and convictions that's not pressuring," Dacus said.
Opponents are considering an appeal of the ruling to the Supreme Court. Lieu said he believes the lower court decision will stand.
