This paper is to account for the fundamental contribution offered by Francisco Suárez, with his De Legibus ac Deo legislatore, in tracing the clear conceptual and operative boundaries of epikeia. In fact, three merits must be recognized to the philosopher: given a clear systematic framing of the epikeia in the interpretation of the law; awarded to epikeia, through a careful work of conceptual clarification, dignity of an autonomous legal institute with respect to similar figures with which other scholars before him easily confused; studied with methodological rigor the different operation of the institute with respect to human law and natural law. In relation to human law, Suárez identifies the three general cases in which it is possible and lawful to make use of epikeia. The theme of the application of epikeia to natural law, however, is so important for the philosopher of Grenade to be object of an autonomous discussion in Chapter XVI of Book II of the work cited. The solution proposed by Suárez relating to the relationships between epikeia and natural law, as will be seen, is different from the ones proposed by other illustrious authors who preceded him, first of all Thomas Aquinas