Hans Kelsen's critique of John Austin has so far attracted little attention among legal theorists. This article argues that Kelsen's attack on Austin anticipated the key elements of Hart's rejection of the Austinian conception of law as sanction-backed sovereign command. At the same time, the way in which Kelsen presents his critique of Austin's conception of sovereignty reveals important differences in purpose and intention between Kelsen's Pure Theory of Law and Hart's legal theory. The Pure Theory of Law is animated by an ideal of legality that is alien to purely descriptive jurisprudential approaches in the Hartian tradition. The article concludes that this difference between Kelsen and Hart merits further exploration and that it might help to show that the Pure Theory of Law is still relevant to contemporary legal theory.