A social psychologist testified Friday in a trial challenging California’s gay marriage ban that leading mental health associations stopped thinking of homosexuality as a mental illness decades ago.

Lawyers for two same-sex couples suing to overturn the voter-enacted ban called University of California, Davis researcher Gregory Herek as an expert witness to bolster their argument that sexual orientation cannot be easily changed.

Herek said leading mental health groups also take a dim view of therapies aimed at making people heterosexual.

The point is central to the plaintiffs’ effort to show that gays deserve the same judicial protection as racial and ethnic minorities.

Read the rest of Lisa Leff’s AP article here.