In the first court verdict of its kind, a jury in New Jersey on Thursday found that a prominent group offering gay “conversion therapy” violated the state’s Consumer Fraud Act by claiming it could help men overcome unwanted homosexual urges.

Gay-rights groups hailed the decision as an important advance in their growing national campaign to discredit and ban so-called reparative therapy, which is based on the theory that homosexuality is rooted in childhood trauma, often caused by distant fathers, overbearing mothers or early sexual abuse, and can be overcome with extended therapy.

Leading psychiatric and medical groups, which stopped branding homosexuality a disorder in the 1970s, have called the theory unfounded and say such therapy is potentially dangerous because it can produce agonizing guilt in young people and turn them against their parents.

In recent years, California, New Jersey, Oregon and Washington, D.C., have banned conversion therapy for minors; a bill that would do so in Illinois awaits the governor’s signature. At a White House Pride reception on Wednesday, President Obama said he supported “efforts to ban conversion therapy for minors.”