Lysias 10 Against Theomnestos is the only surviving example of a classical Greek speech on a charge of slander (dikē kakēgorias). The case turns on establishing communal consensus in evaluation of meta-discursive claims: assertions as to what the law says about what citizens can say about their fellow citizens. I adapt Marmor’s account of the pragmatics of legal discourse to illuminate the litigants’ strategies as they seek to control interpretation of the legal question in this much-discussed case from 380s BC Athens. We see how each party used different assumptions about the law’s implicatures as well as its declarative meaning and presented these assumptions as grounded in common sense. The persuasive methods used by Lysias’ client are illuminated by means of cognitive narratology’s application of Lewisian possible-world logic to the creation of story-worlds and the relationships they generate between narrator and reader/audience. So understood, Lysias’ speech helps answer questions about the role and limits of free/frank speech (parrhēsia) in democratic Athens and about the relationship between individual agency and the collective agency of the dēmos, questions crucial to an understanding of the place of legal discourse and legal conflict in the ideology and day-to-day praxis of the democratic city.