Law are equivalent to Rules in a game, and Judges are equivalent to Referees. There is no greater cause than the most efficient way to keep order and let business as usual continue.
Ethics and Morality on the other hand has religion guiding it, along with customs and practices of that particular society.
I will let the Atheist speak for himself.
But rules cannot be arbitrary or the players will revolt. It has to be based on common consent, which often arises from a visceral sense of right and wrong - almost a hard wired code.