This short essay deals with the analysis of verb tenses’ functions in the language variety testified by the Atti del podestà di Lio Mazor. It is a series of judicial documents written at the beginning of the 14th century in a small village in the Venice Lagoon. They show an archaic state of language, in which the Simple Past is still productive, while nowadays in Northern Italy it has disappeared from the varieties spoken in the area, that use only the Present Perfect. In the 1980s, some typological studies on Romance languages identified in the expansion of the semantic functions related to the Present Perfect a diachronic process named aoristic drift. In this paper, we analyze the linguistic distribution between Present Perfect and Simple Past showed by the Atti in the light of the aoristic drift’s theory. We also integrate this theoric background by applying a refined textual analysis to the documents. The combination of linguistic theory and text analysis to investigate ancient language varieties is the innovative element of the present work, with respect to the traditional studies about aoristic drift.