Heavyweight rule???

So first of all forget about semantics, I'm not naming any names here, But lol, is there a special rule or silent agreement like teddy atlas would call it, per say that; Certain fighter A) can sign contract to fight while using peds and so can his opponent as long as they sign away allowing permission to use such drugs and not be held liable about what happens physically? It's like that saying everybody else is doing it, why can't I? So essentially Observe a hw fight. Big buggar wins the fight with a pulveriizing ko, it doesn't matter what's in his system as long as you know the results could take a toll on the opponent s health AS LONG AS he knows boxer a is doping, and he can as well. Is there truth to such thing. I'm not trying to disrespect the heavyweight division so if this is at all condisending I had no harm, just looking for a view from those on the inside looking out, who know the game better than I do or else remove my post. Peace!!! Sorry for my ignorance btw.