European Review of Public Law, vol.31, no.2, pp.433-459, 2019 (Peer-Reviewed Journal)
Kelsen stands as the only positivist theorist with a coherent theory of international law. While others like Austin and Hart continued to doubt the legal character of international law, Kelsen ventured to include international law in his famous pure theory of law. However, the inclusion of international law into pure theory has caused certain “impurities” within the theory, problematizing the relationship between international and municipal legal systems. This article determines two main impurities in Kelsen’s account of the relationship between international law and municipal law. The first is caused by the notion of basic norm. It is defended that although this notion is very problematic and it has been challenged by many scholars in the past, it is not possible to get rid of the basic norm while continuing to support Kelsen’s normative positivism based on the dualism of “is” and “ought”. The second impurity relates to the prioritization of international and municipal legal orders. Kelsen shows a certain tendency to accept the supremacy of international law over municipal law. Meanwhile, he also acknowledges that supremacy of municipal legal order over international law could also be established. It all depends on which basic norm one presupposes to start with: the basic norm of international law or that of national legal system. It is argued that, after illustrating the unity of these two legal systems, it is frivolous to assert that one is superior to the other.