This paper treats the question of knowledge of fact in the legal context, especially in the paradigmatic context of a trial. Moving through the analysis of its fundamental dialogical structure, and lingering on the transcendental value of dialogue, attention is given to the activity of the parties involved in a trial (namely lawyers and prosecutors), with the aim of understanding how they come to acknowledge and represent fact. The idea is to avoid the extremes of both dogmatic and sceptical stances with regard to the existence of fact, stating that both facts and interpretation exist, in the sense that it is impossible to acknowledge facts without interpretation. The final aim is to show the peculiar role that vagueness of language plays in a trial so as to outline a “classical” model of legal logic.