SACRAMENTO — A first-of-its-kind ban on a controversial form of psychotherapy aimed at making gay people straight could face a key vote Tuesday by a group of California lawmakers.

Supporters say the legislation, which is before its final committee, is necessary because such treatments are ineffective and harmful.

“This therapy can be dangerous,” said the bill’s author Sen. Ted Lieu. He added the treatments can “cause extreme depression and guilt” that sometimes leads to suicide.

Conservative religious groups emphatically reject that view of sexual orientation therapy and say the ban would interfere with parents’ rights to seek appropriate psychological care for their children.

“While this is a direct assault on everyone’s freedom it is also a not so subtle attack on religious liberty,” the National Association for Research and Therapy of Homosexuality said in a statement.

The debate comes as gay rights issues take the spotlight around the nation.

Over the weekend, Vice President Joe Biden said he is “absolutely comfortable” with same-sex couples getting the same rights as heterosexual couples.

In North Carolina on Tuesday, voters weighed in on an amendment defining marriage as solely between a man and a woman. And in Colorado, a measure to extend civil union protections to gay couples faced a looming deadline in the state Legislature.

The California bill would prohibit so-called reparative therapy for minors and obligate adults who chose to undergo the treatment to sign a release form that states that the counseling is ineffective and possibly dangerous.

AB1172, sponsored by Equality California, will go to the full Senate if approved Tuesday.

Lieu says attempts to pathologize and change people’s sexual orientation should be treated akin to smoking and drinking: harmful activities that adults can choose to participate in, but children cannot.

“We let adults do all sorts of stupid and risky things, but we ban dangerous things for young people,” Lieu said in a telephone interview.

He was inspired to take up the issue by a cable news documentary featuring people whose parents had attempted to change their sexual orientation. The doctor featured in the show “was evil,” he said.

Interest in the religion-based therapy appears to have surged in recent years, sparking debates about whether sexual orientation is an immutable characteristic or something people can change.

Exodus International, the world’s largest Christian referral network dealing with homosexuality, now steers people to 260 groups across the country, up from about 100 a decade ago. The organization has 35 ministries and churches scattered around California, from the Central Valley to the U.S.-Mexico border.

Mainstream mental health organizations say people shouldn’t be seeking out groups like Exodus at all.

The American Psychological Association said in 2009 that mental health professionals should not tell gay clients they can become straight through therapy.

The association cited research suggesting that efforts to produce the change could lead to depression and suicidal tendencies, and stated that no solid evidence exists that such change is possible.

The American Counseling Association and American Psychiatric Association have also disavowed the therapy. The psychiatric association removed homosexuality from its list of mental disorders nearly 30 years ago.

Last month, the author of a widely-cited 2001 study supportive of the notion that “highly motivated” people can change their sexual orientation retracted his study and apologized to the gay community.

Gay rights advocates say a ban like the one proposed in California could represent a turning point, and inspire similar legislation in other states.

The measure would likely face legal challenges from opponents who say it is unconstitutional. Lieu says he addressed free speech issues by excluding clergy from the legislation.

Conversion therapy penetrated the national consciousness last year when former Republican presidential candidate Michele Bachmann was questioned over whether the Christian counseling business of her husband provided therapies that attempted to change gays and lesbians.

The practice has garnered attention in past years as teens sent by their parents to conversion therapy programs have shared their stories online.