GURPS

This seems like the most pragmatic approach. Personally, in my upcoming game, I'm planning to basically go with my gut while allowing my players to challenge my rulings at any time. If they do, they can reference a specific mechanic they think should be used, and I'll either agree or counter.

That way, things keep moving most of the time, but players don't feel like they suffered some crucial irreversible consequence because of flippant or inconsistent rulings. I think putting the burden of finding the rule primarily on the player also prevents overzealous challenges from bogging the game down.