A bill at California’s state legislature which would ban attempts to turn gay minors straight through therapy and require adults to be informed of the unproven effectiveness of such treatments is expected to be voted on at the senate later today.

The bill, which outlaws such therapies for minors and requires adults to be told that counselling is ineffective and dangerous, is authored by Senator Ted Lieu, who has said that such therapies “can be dangerous” and cause “extreme depression and guilt” which may lead to suicide.”

The American Psychological Association, the World Health Organisation and other psychiatric and psychological organisations believe there is no credible evidence that such ‘therapies’ can produce change in sexuality but can cause harm to patients.

The bill would require adults to be provided with a statement ahead of such therapy which begins: “Having a lesbian, gay, or bisexual sexual orientation is not a mental disorder. Sexual orientation change efforts have not been shown to be safe or effective and can, in fact, be harmful. The risks include, but are not limited to, depression, anxiety, self-destructive behavior and suicide.”

Opposing the draft legislation, designated SB 1172, NARTH, the National Association for Research and Therapy of Homosexuality, has said there is also no evidence that efforts to change sexual orientation definitely do not work and added that harm can be experienced in all forms of psychotherapy.

In a statement last month, NARTH said: “What we can say with confidence is that some SOCE [sexual orientation change efforts] clients report harm and others report benefit and we do not know from the scientific literature how often either outcome occurs.”

Equality California, which sponsored the bill along with the National Center for Lesbian Rights, said the bill was likely to be voted on today.

Opposing the bill, the California Psychological, said professional bodies had already passed resolutions based on their own data and research: “Each profession has a national organization with a prescribed Code of Ethics, as well as state organizations and licensing boards to which they report and weigh in on professional and ethical conduct. The statutory ban on types of therapy is not the right venue and there is very little precedent in state law to make an outright ban on a specific type of therapy.”

Equality California said: “Sexual orientation change efforts pose critical health risks to lesbian, gay, and bisexual people, including depression, shame, decreased self-esteem, social withdrawal, substance abuse, risky behavior and suicidality.

“Recognizing that there is no evidence that any type of psychotherapy can change a person’s sexual orientation, and that sexual orientation change efforts may cause serious and lasting harms, the American Psychiatric Association, the American Psychological Association, the American Counseling Association, the National Association of Social Workers, and the American Academy of Pediatrics uniformly oppose efforts to change the sexual orientation of any individual.”

The group urged efforts to raise support for the bill with Assembly members, where the bill will head if it passes the senate.