The motto of my alma mater is "leges sine moribus vanae" --- laws without morals are useless.

Laws are just a codification of a moral system. But it is an imperfect one, and you can't enforce morality in the form of laws. Humans are free to be unscrupulous and skirt around the law or break it, but it's even worse for AI, because there is no innate compass pointing it toward something being good or bad.