Starting from a critical reinterpretation of the debate on the evolutionary lines of lay historiography in the medieval commune, the essay investigates, on the basis of a new analysis of the Gesta Triumphalia per Pisanos facta, the cultural phenomenology and the lines of development of the ‘historiography of judges’ in the 12th century. In particular, the essay highlights, from a comparative perspective, the relevance of the socio-professional segment of judges and legal experts (and not notaries) in the writing of the chronicles of this period. Within this group, the chronicles had a mode of circulation that was neither public nor private, but which can be placed in an intermediate phase that refers to the way in which the authors and the readers used them.