California Governor Jerry Brown has signed a bill banning therapies that attempt to alter a minor's sexual orientation from gay to straight, making California the first state to enact such a law.

The measure (Senate Bill 1172) was sponsored by Senator Ted W. Lieu, a Democrat from Torrance, and supported by dozens of organizations, including the National Center for Lesbian Rights (NCLR), Equality California (EQ), Courage Campaign, Lambda Legal and Mental Health of Northern California.

“Governor Brown today reaffirmed what medical and mental health organizations have made clear: Efforts to change minors' sexual orientation are not therapy, they are the relics of prejudice and abuse that have inflicted untold harm on young lesbian, gay, bisexual and transgender Californians,” Clarissa Filgioun, board president of EQ, said in a statement.

“This law will ensure that state-licensed therapists can no longer abuse their power to harm LGBT youth and propagate the dangerous and deadly lie that sexual orientation is an illness or disorder that can be 'cured,'” said NCLR Executive Director Kate Kendell.

The National Association for Research & Therapy of Homosexuality (NARTH), a group which promotes such therapies, had called on the governor to veto the measure.

On its website, the group claimed that passage of the bill would “likely increase harms to minors through its unintended consequences.” Parents, the group explained, would be forced to seek out therapy for their children from “unlicensed, unregulated and unaccountable religious counselors.”

“The vast majority of anecdotal accounts of harm to children from SOCE [Sexual Orientation Change Efforts] seem attributable to these types of counselors and to religiously oriented programs.”

Meanwhile, the “ex-gay” group Exodus International recently announced it would no longer offer such treatments, saying they don't work.

(Related: Dr. Robert Spitzer regrets 2001 study supporting “ex-gay” therapy.)