I'm going to assume that you mean the "natural law" that sexual acts should be designated for the purpose of procreation? Ever have anal sex with your wife? Ever get a blowjob? Ever use a condom so that your partner wouldn't get pregnant? If so, then you did so for pleasure and not procreation. How is that any different from two guys having anal sex or blowing each other?
And by the way, just a few decades ago it was acceptable to say that an interracial marriage was against the natural law. Social progress, dude...you can't stop it.