This discussion considers Kelsen’s engagement with natural law theories and the contours of his rejection of natural law as a methodologically coherent legal theory. It juxtaposes Kelsen’s refutation of natural law theories with his assertions as to the logical superiority of his legal science of positive law. It also reflects upon not only the ‘objectivity’ of Kelsen’s legal science, which Kelsen elaborates and delineates in contrast to natural law theories and their inherently arbitrary and subjective elements, but also his construction of a ‘value-free’ legal positivism in which the legal order is constituted in the autonomous normative order of positive law. In addition, the authors analyse Kelsen’s position regarding the cognitive operation of the Grundnorm, along with the relationship between the ‘basic norm’ and the theory of levels (Stufenbaulehre), so as to explicate his account of the creation and operation of legal norms and of the simultaneously dynamic and static character of his legal positivism. The authors demonstrate that Kelsen sought, in his denunciation of natural law theories, not only to advance his legal science of positive law but also to safeguard its theoretical and methodological rigour from the dangers of a wholesale return to natural law theories. In this respect, the authors scrutinise Kelsen’s critical engagement with Aristotle, Dante, Althusius, Wolff, Rousseau, Kant, Rickert, Cassirer, Schmitt, Strauss, Verdross and others associated with the natural law tradition. The contemplation of Kelsen’s assault on natural law theories also explores Kelsen’s legal monism vis-à-vis State sovereignty and international law, his thoughts on legal validity and authority, the function of normative imputation in legal positivism, the Neo-Kantianism of the Baden School, the interrelation between norm, sanction and coercion in legal positivism, the State as juridical entity and Kelsenian perspectives on constitutionalism and democracy.