Legal discourse centrally involves a family of normative expressions - "obligation," "right," "permission," and so on - whose surface grammar parallels that of moral discourse. Is the normativity of legal discourse then a moral normativity? Or is it a distinct type of normativity altogether? Answers are disputed.
Custom is among the sources of law. That much is agreed. But custom can also be law, independently of promulgation, or so many believe. The issue raises further questions. Is custom normative, and if so, how? Insofar as a customary norm is (or becomes) a legal norm, does it manifest (or acquire) a different kind of normativity? Or does its original normativity contribute to the normativity of law?
Another set of questions has to do with custom as a condition of legal validity. Kelsen wrote that the doctrine of desuetudo states a necessary condition of a norm's legal validity. In contrast, Hart's view was that desuetudo is a doctrine that a legal system might take or leave, and that norms that are customarily ignored may nonetheless possess legal validity.
I will explore the hypothesis that every legally normative utterance resolves into one expressing (a) custom-implicating moral normativity, (b) custom-extending moral normativity, or (c) normativity "in the manifesto sense" (to enlist a phrase of Joel Feinberg's). If this is correct, there is no such thing as a distinctively legal brand of normativity.