"... We live in a law-ridden society; law has cannibalized the institutions which it presumably reinforces or with which it interacts.... [W]e are encouraged to assume that legal behavior is the measure of moral behavior.... Efforts to legislate conscience by an external political power are the antithesis of custom: customary behavior comprises precisely those aspects of social behavior which are traditional, moral and religious--in short, conventional and nonlegal. Put another way, custom is social morality. the relation between custom and law is basically one of contradiction, not continuity.
"Thus, law is symptomatic of the emergence of the state. ...Custom--spontaneous, traditional, personal, commonly known, corporate, relatively unchanging--is the modality of primitive society; law is the instrument of civilization, of political society sanctioned by organized force, presumably above society at large and buttressing a new set of social interests. Law and custom both involve the regulation of behavior but their characters are entirely distinct...."
Diamond, Stanley, in "The Rule of Law versus the Order of Custom," in In Search of the Primitive [Transaction Publishers, 1981]; also in Bonsignore, et al., Before The Law, Fifth editon [Boston: Houghton Mifflin, 1994]