Kelsenian legal science is a distinctive theoretical project for the comprehension of positive law. It distinguishes itself from the broader, nineteenth century German tradition of legal science through a process of critical interpretation and reworking. The process, initiated with Kelsen's habilitation of 1911, Hauptprobleme der Staatsrechtslehre entwickelt aus der Lehre vom Rechtssatze (Kelsen 2008), represents a reconsideration of the fundamental elements of this tradition which preserves the methodological requirement for a theory of law to be a science. The adoption of this interpretative position entails that the Kelsenian project assumes both the continued pertinence of a notion of legal science and the historical legitimacy of the tradition of legal science in relation to preceding conceptions of a theory of law. The tradition of legal science is held, in the 1911 habilitation, to denote the origin from which further work on a theory of law is to develop.