The law, which was passed by the California Legislature and signed by Gov. Jerry Brown in October, bars licensed psychotherapists from working to change the sexual orientation of gay minors.
U.S. District Court Judge William Shubb ruled that the law may violate the First Amendment rights of psychiatrists, psychologists and other mental health professionals who engage in "reparative" or "conversion" therapy.
"Even if SB 1172 is characterized as primarily aimed at regulating conduct, it also extends to forms of (conversion therapy) that utilize speech and, at a minimum, regulates conduct that has an incidental effect on speech," Shubb wrote.
Shubb limited the scope of his order to just the three providers who appealed to him to overturn the measure, which is set to take effect on Jan. 1. The people are psychiatrist Anthony Duk, marriage and family therapist Donald Welch, and Aaron Bitzer, a former patient who is studying to become a counselor who specializes in clients who are unhappy being gay.
The judge also disputed the Legislature's finding that trying to change young people's sexual orientation puts them at risk for suicide or depression, saying it was based on "questionable and scientifically incomplete studies."
The law, which was passed by the Legislature and signed by Gov. Jerry Brown in October, states that therapists and counselors who use "sexual orientation change efforts" on clients under 18 would be engaging in unprofessional conduct and subject to discipline by state licensing boards. It is set to take effect on Jan. 1.
The exemption for the three people will remain in place only until Shubb can hold a trial on the merits of their case, although in granting their request, Shubb noted that he thought they would prevail in getting the law struck down on constitutional grounds.
The Associated Press contributed to this report.