In this chapter, the epistemological bases of the so-called Communicational Theory of Law (hereinafter CTL) are presented. The CTL is characterised by a clear distinction between legal order and legal System, as well as by the use of the hermeneutic-analytical method. CTL is a unique theory of law that has been developing for four decades and whose ideas have been discussed all over the world. On this occasion, its founder has the opportunity to present to the English-speaking community the theoretical bases of his particular vision of Law.