This article offers an unprecedented empirical window into prosecutorial discretion drawing on long-term participatory research between 2013 and 2017. The central finding is that jurors play a vital role in federal prosecutors’ decision-making, professional identities, and formulations of justice. This is because even the remote possibility of lay scrutiny creates an opening for prosecutors to make common sense assessments of (1) the evidence in their cases, (2) the character of witnesses, defendants and victims, and (3) their own moral and professional character as public servants. By facilitating explicit consideration of the fairness of their cases from a public vantage point, I argue that imagined jurors serve as an ethical resource for prosecutors. Part I reviews contemporary legal and interdisciplinary research on the declining number of jury trials and prosecutorial discretion in the United States. Part II describes the ethnographic research method deployed in this case study, noting its unique capacity to document off the record decision-making practices. Part III presents the empirical findings of this study with attention to how hypothetical jurors inform prosecutors' evaluations of their cases, evidence, investigations, and plea agreement discussions. Part IV considers several explanations for hypothetical jurors' perceived relevance to prosecutors' work beyond their instrumental and strategic value. Part V concludes that the U.S. Attorney’s Office that is the subject of this study models the democratizing potential of lay decision-makers, even in hypothetical form. This finding contributes a novel rationale for fortifying the U.S. jury system and a novel perspective to the study of prosecutorial ethics.