This article proposes to elucidate Wilfrid Waluchow’s notion of constitutional morality by explaining how it relates to the classical common law idea of artificial reason. It examines how Waluchow’s effort to reconcile insights from the thought of H.L.A. Hart and Ronald Dworkin through the idea of constitutional morality is both reminiscent of the artificial reason of the common law and distinct from it. It shows that constitutional morality evokes the subtle union of custom and reason found in artificial reason, but (...) also that it proposes, under the influence of Hart’s notion of rule of recognition, a narrower understanding of law’s foundation in established practices, and that it gives, consistent with Dworkin’s vision of law as integrity, a greater theoretical scope to law’s rationality. (shrink)