Abstract: This chapter argues that the dominant discourse between retributivism and social welfare theory about the purposes of punishment inevitably tends toward overpunishment. This is partly due to the current set of political and social arrangements (leading both to differential rates of offending and differential policing in poor and minority communities) and partly to human cognitive biases. One way to counter this tendency is by promoting greater discretion to decline punishment on the part of institutional actors throughout the criminal justice process. This argument amounts to a ‘prudential’ case for mercy in criminal justice — a case premised not on a new theory of the relationship between justice and mercy, but rather on the predictable failures of existing theories of just punishment.