  The relevant notion of justification has two aspects. First, the principles and therefore the moral facts that they reflect give reasons why any aspect of institutional practice or other nonmoral consideration bears on legal rights and obligations. The principles therefore explain why any such consideration is legally relevant. Second, the principles thereby determine how any such consideration bears on rights and obligations. An interpretivist might say that certain principles of fairness or procedural justice give enactments some role in determining rights and obligations. The precise role depends on the precise reasons why enactments should have it. An appeal to principles of fair notice might give, other things equal, a central role specifically to the plain meaning of the text of enactments. But on the hypothesis that democratically constituted assemblies have justified power to shape rights and obligations as they choose, some conception of such assemblies’ linguistic intentions, or of their intention to affect the law in some particular way by the relevant enactment, might be given priority. There may be special cases. An interpretivist might say that, because fair notice is essential to the permissibility of criminal punishment, criminal statutes affect the law only as narrowly construed. An interpretivist might further say that, in all cases, certain more specific moral principles control “the operation and effect” of all laws (as the Riggs v. Palmer court famously said, 115 NY 506 (1889)).