The television illusionist Derren Brown is courting controversy again by planning his most audacious trick yet – persuading a straight man he is gay. The hypnotist also believes he could make a gay man be attracted to women.I'm not sure how he would "prove" it either way. If he got the hypnotized person to preform a sex act, I guess you could say he made his case. If the person wasn't a plant from the audience, I think Mr. Brown would find himself in a lawsuit.
Of course if hypnotherapy was proven to be an effect long term tool in realigning a homosexual to heterosexual interests and behavior, it would immediately be illegal in California and Massachusetts.