This article examines the jurisprudential arguments elaborated in David Dyzenhaus's The Long Arc of Legality. In particular, it looks into the main claim of the book: that the fact of 'very unjust laws' is central to illuminating the idea of law's authority, the elaboration of which Dyzenhaus takes to be the purpose of legal theory. The article analyses Dyzenhaus's own normative proposal in this matter, which consists of a version of legal positivism committed to Lon Fuller's principles of the internal morality of law, with the corollary of a conception of the judicial role as bound to a duty to apply these internal principles of legality when exercising their main function. While I cast some doubts on the feasibility of constructing the judge's function that way, in the end I celebrate Dyzenhaus's attempt at refining legal positivism's identity, especially in light of the ongoing debate with contemporary anti-positivism.