If the people follow a moral code and don't commit crimes in the first place, the law enforcement system punishments are rendered useless and therefore people acting on their high moral values out weigh the power of the laws that govern them. If the law is never broken, there is no need for the law in the first place.
There's a need for stringent laws to keep humans in time. As crazy as this might sound to some ,though it's true that the humans are too conditioned , too mainstreamed to be given the liberty to have control over all their desires. The hope of having morally sound humans with intacts ethics is too far fetched. This is never happening. We need to have boundaries set for us . Giving us absolute freedom in anything will eventually lead to havoc. We prone to get influenced easily being the social animals that we are especially . We thrive on interaction , sharing of ideas, there is always a high possibility of being prejudice , of being influenced by the surrounding in decision making . Strict laws , proper boundaries , limitations are an absolute must of every individuals .
The same man who would never steal even a pen by accident when starving will eagerly steal the next loaf of bread. Human the Animal will sate it's needs through any means necessary for the most part even if Human the Rational Being disagrees with the methods. Morals are far too fickle to allow; an extremely sound example would be crimes of passion where people harm or slay other people after catching them in certain acts or assaulting others. These are not normally killers but were roused to such behavior and if Human the Animal is susceptible to this and like behaviors (such as risky behavior relating to "showing off", drug use or other mind altering states and substances, etc.) then the moral stability goes right out the window.