Monumental complete work of 12 volumes. The figure of his father, Constantine, one of the most prominent exponents of Neapolitan political and intellectual life of the time, dominated Gregorio's life and directed his education from the very beginning. Gregory himself underlines this in the Preface to the "History of the laws", where he recalls how his father had constantly guided him in his studies dedicated to the feudal and municipal law of the Kingdom, in which the influences of Giambattista Vico, his professor of history, philosophy and literature. Giustiniani confirms that the idea and the plan of the work were Costantino's, to whom Ginesio "naively confessed it a thousand times". The inspiring intent of the initiative was to rewrite Gianno's history by eliminating its "poisons" and strengthening its juridical and historical aspects. The "History of the Laws" depends completely on Giannone's work and follows in his footsteps, relegating political and religious problems to the sidelines, deleting the anti-Curialist part and attenuating the aspirations of civil and religious reform which constituted the predominant part. The result was a "moderate version" of the Civil History.