Presumption of Innocence and Deterrence

Prodefendant rules in criminal procedure, such as the presumption of innocence, are usually suspected of undermining deterrence. We investigate the soundness of this claim in a model in which criminal-law enforcers decide about their investigating effort under either the presumption of innocence or the presumption of guilt. We show, under some conditions, that the presumption of innocence may minimize the social costs of crime, when compared to the presumption of guilt, by inducing the law enforcer to increase investigative efforts, thereby improving deterrence.