Against legal positivism, which maintains the separate identity and independence of morality and the law, a legal system is best viewed as the formal development of a subset of the social rules of a society. The core of a legal system is its criminal code, and for various reasons, that normally approximates the main outlines of the shared moral beliefs in the society. There are various devices which function to insure this close connection of the criminal code with the social rules. The cooperation of citizens, which is crucial to most successful prosecutions, frequently depends upon the citizens' acceptance of the criminal laws.
Judges typically appeal to moral principles in the interpretation and application of moral rules.
In the main, it is not the existence of sanctions, but the acceptance as morally correct of the social rules which the criminal code reinforces and clarifies and modifies, which explains the obedience of most citizens most of the time. Yet, we must concede to the legal positivists that legal rules do differ in some crucial ways from the social rules which they reinforce. In the first place, these rules are developed in a legal system in such a way as to accommodate certain administrative necessities. But not only are there limitations in the ways the legal system reinforces social rules which are due to administrative necessities, there are limitations which are designed to protect certain valued social institutions from the invasive procedures of a legal proceeding. Thus, there are privileges against self-incrimination, against compelling a priest to divulge the confession of a penitent, against compelling a businessman to divulge trade secrets, and so on.