Lay participation in criminal trials has primarily been studied in common law systems, thereby mainly focusing on the separate role of juries. These studies have provided detailed accounts of language use between jurors during deliberation as well as their use of storytelling techniques and common-sense reasoning in decision-making. However, only few studies have focused on the linguistic learning processes that lay judges in other legal systems go through when they deliberate cases together with a professional judge both in reaching a verdict and in sentencing. In Denmark, lay judges are appointed for a period of four years, and this paper presents findings from an ethnographic study of lay judges and their growing experience with interactions in the deliberation room. It argues that lay judges learn to use legal language in order to strengthen their arguments vis-à-vis the professional judges. Lay judges feel that their influence is dependent on how well they master new, legal context-specific ways of expressing themselves, a point that may run counter to their legitimation as lay voices in an otherwise formalized judiciary.