The teaching of the theory of law already has a certain tradition in the curricula of law schools, even though with that name it has not appeared in them until recently. Along with the different dogmatics, which aim to study current positive law, the theory of law aims to achieve a higher level of abstraction, accounting for the structure and functioning of legal systems in general or, at least, the physiognomy that present such systems within the framework of modern legal culture. However, and apart from the fact that a clear and absolute separation between theory and dogmatics may not be possible or desirable, the teaching purpose that animates these pages constitutes an additional reason to have tried to offer a construction attentive to the concrete determinations of the positive Law . Therefore, without abdicating the approach and concerns that characterize the theory of law, we have always tried to contrast their contributions in the test bench of the current regulatory system, which ultimately represents the fundamental object of knowledge for Our students. These Notes want to be a contribution more, and without a doubt, as it already announces its title, one of the most modest, to the consolidation of a certain way of understanding the theory of Law that has known an unquestionable development in the legal literature of the last time; a theory elaborated from the legal philosophy, but that has renounced the old illusion of constructing ideal models completely disconnected from reality and of what constitutes the unavoidable point of reference of any reflection on Law.