I suppose the moral code that should be the basis of law is respect for individual rights. Basically, that violence, theft, and fraud are wrong.
In many ways the basis I'd like is different from the basis that is currently used for our laws, which is majoritarianism. But in some ways I'd say it is similar, in that a few areas still remain where the majority respects the rights of individuals.
What moral code do you think should be the basis of our laws?