Since fallibility is unavoidable, any criminal justice system must decide how the risk of error should be distributed. The traditional view holds that a false conviction is morally far worse than a false acquittal. Therefore, erroneous outcomes must be distributed asymmetrically to avoid, to the highest possible extent, convicting the innocent. This article casts doubts on this assumption. It postulates that the traditional view defends a markedly asymmetrical distribution of erroneous outcomes, because it neglects the preventive cost of acquitting the guilty. After a theoretical and empirical analysis, this article concludes that crime prevention must be considered when establishing the level of the standard of proof; and, when it is considered, pro tanto reasons emerge to adopt a weaker standard than that normally deemed appropriate in criminal cases. The article also examines three possible reasons why preventive arguments are not considered when establishing the criminal standard of proof. It concludes that ignoring the consequences of the standard of proof on crime cannot be justified by the distinction between statistical and individualised victims, or by that between distribution and concentration of harm, or ultimately by that between action and omission.