For centuries, state sovereignty has supplied a sound historical and social basis to obedience ? on the one side a socially shared ethos and on the other side the concrete efficacy of law and its sanctions. Vis-à-vis the crisis of the sovereignty principle, law’s effectivity has taken a number of different shapes. The modern and technical vision of law, à la Kelsen, has brought this concept to coincide with sheer obedience, i.e. concrete social behaviour seen from downstream. In their turn, the theories inspired by legal realism (in some cases echoing a kind a neo-mediaevalism), firmly opposed as they are to Kelsenian normativism, point to self-regulation and the aptness of legal systems to keep their equilibrium homeostatically, while rejecting sovereignty as a mere fiction. Professor Catania stresses that a purely formalist vision of facts is misleading, as it ignores that legal rules are themselves deeply affected by conflicts and tensions. He therefore suggests that Herbert Hart’s internal viewpoint leads to a more fruitful vision oflaw’s effectivity, conceived of as the concrete normative orientation of a citizenry ? a conception based on social responsibility and power, where the profound nihilist kernel of the concept of sovereignty comes to be dissolved.