A Colorado gay man is testifying in a federal same-sex marriage trial about his experience undergoing so-called “reversal therapy” that attempted to change his sexual orientation.

Lawyers for two same-sex couples suing to overturn California‘s gay marriage ban called 26-year-old Ryan Kendall to the witness stand to demonstrate that a person’s sexual orientation cannot usually be changed.

The point is central to their effort to show that gays deserve special protections from discrimination under the U.S. Constitution.

Kendall said the therapy he underwent at the insistence of his parents while a teenager drove him to the brink of suicide and did nothing to turn him into a heterosexual.

A lawyer for the ban’s sponsors objected to Kendall being allowed to testify, saying it’s irrelevant to the legal issues in the case.