Well, hopefully you are playing with adults, and you all have the same objective (to have fun together). But, yes there will always be those dictator GMs and insolent players.
But part of the GMs job is to keep things moving forward... And sometimes that means making a call that may be unpopular or even wrong! However, as long as the call is applied to all sides, any harm is mitigated. A good GM should also use his down time to look up the actual rule and then revisit the call made with the players and discuss the differences between what he called and the actual rule.... Sometimes everyone will agree that the call "better" and thus house rule that way perminately.
Being wrong is a fact of life, we will all be wrong at some time. It's how we handle being wrong that matters.