Este art?culo presenta y contrapone las teor?as del derecho de los juristas Bruno Leoni y Hans Kelsen, quienes pertenecen a diferentes corrientes jur?dico-filos?ficas. De esta manera, se recogen y sistematizan los cuestionamientos que el primero realiz? al segundo. As?, se aborda la pregunta por el fundamento de sus cr?ticas y se presentan los argumentos que permiten concluir que dicho fundamento es la distinci?n que Kelsen realiz? entre el mundo del ser y el del deber ser.This article aims to present and contrast the theories of law of the jurists Bruno Leoni and Hans Kelsen, who belong to different legal-philosophical trends. In this way, the questions that the first asked the second are collected and systematized. Thus, it addresses the question about the basis of his criticisms and presents the arguments which allow concluding that such foundation is the distinction that Kelsen made between the world of is and ought.Universidad de Ibagu?