Gov. Christie signed a law Monday banning gay conversion therapy for children, making New Jersey the second state to outlaw the controversial practice that seeks to make gay people heterosexual.

The bill, which passed the Legislature in June, bans licensed counselors from engaging in "sexual orientation change efforts," including "efforts to change behaviors, gender identity, or gender expressions, or to reduce or eliminate sexual or romantic attractions or feelings toward a person of the same gender."

Gay-rights groups praised lawmakers. "There is no greater achievement than helping to stop the abuse of our youth," Troy Stevenson, executive director of Garden State Equality, which advocates for gay rights, said in a statement. The ban "will do just that."

The bill cites extensive research by organizations such as the American Psychological Association showing that such therapy can cause depression, suicidal thoughts, substance abuse, and decreased self-esteem.

"The most important fact about these 'therapies' is that they are based on a view of homosexuality that has been rejected by all the major mental health professions," the association says on its website.

The American Psychiatric Association declassified homosexuality as a mental disorder in 1973.

Christie has said he is wary of letting government tell parents how they should raise their children, but also has expressed concerns about the health risks associated with conversion therapy.

"On issues of medical treatment for children, we must look to experts in the field to determine the relative risks and rewards," he said in a statement Monday.

Referring to the scientific research, he added: "I believe that exposing children to these health risks without clear evidence of benefits that outweigh these serious risks is not appropriate."

California passed similar legislation last year, but it has not yet been implemented because of litigation. On Monday, the nonprofit Liberty Counsel vowed to file suit against New Jersey to block the law. "This bill provides a slippery slope of government infringing upon the First Amendment rights of counselors to provide, and patients to receive, counseling consistent with their religious beliefs," Mat Staver, the group's founder and chairman, said in a statement.

Stevenson said he was confident that New Jersey's law would withstand any legal challenges because the lawyers who crafted it closely examined vulnerabilities in the California law.

About 70 therapists advertise a conversion therapy practice in 20 states and the District of Columbia, including two in New Jersey, according to the Southern Poverty Law Center, a prominent civil-rights group.

In November, the center filed a lawsuit under the state's Consumer Fraud Act against a Jersey City conversion therapy group called Jews Offering New Alternatives for Healing (JONAH).

The suit, filed on behalf of four of the group's former clients, alleges that JONAH falsely claimed that its services were "effective in changing a person's sexual orientation from gay to straight." Last month, a Superior Court judge in Hudson County threw out a motion to dismiss the case.

Assembly Democrats introduced the bill in October, with one calling the therapy "a form of child abuse."

In March, a state Senate committee heard testimony from people who had undergone conversion therapy. They told of being shocked with electricity and being forced to masturbate while looking at images of naked women.

Others said therapy had been effective in helping them lead happy heterosexual lives.

Later that month, the issue became the source of an unlikely campaign controversy, when Christie, a Republican, was noncommittal about signing the law.

His Democratic challenger in November's gubernatorial election, State Sen. Barbara Buono (D., Middlesex), lambasted Christie as showing "a stunning level of ignorance."

Christie vetoed same-sex marriage legislation last year, saying something as consequential as changing the institution of marriage should be put before voters. He also has said that he believes people are born gay and that homosexuality is not a sin.

As Christie mulls a potential presidential bid in 2016, any position he takes on gay rights is likely to draw scrutiny. But any criticism Christie might face for signing Monday's bill will likely come from people who already thought he wasn't conservative enough on other issues, said Patrick Murray, director of the Monmouth University Polling Institute.

"I think his hope is it's seen as common sense, and that this is really a nonissue when the 2016 Republican contest rolls around," he said.

Brigid Harrison, a political scientist at Montclair State University, said Christie's signatures on this bill and others are indicative of a long-term political strategy.

"What we see here is the governor recognizing that while that conservative vote is enormously important in the primary process . . . the reality is that if he is successful, he also needs to appeal to Democrats and independents to be victorious in a general election," she said.

Stevenson signaled that his group would press Christie to take further action to support gay rights.

"We hope that his realization - that there is nothing wrong with our LGBT youth - and that there is nothing about them that needs to be fixed will lead to a further evolution," Stevenson said.

"We must provide all N.J. youth with acceptance, with hope for the future, and, yes, the promise of the dignity to marry the person that they love," he said.

Contact Andrew Seidman at 856-779-3846, aseidman@phillynews.com or @AndrewSeidman on Twitter.