Many legal systems require a high standard of proof for convicting suspects in criminal trials. The standard of proof beyond a reasonable doubt reflects this approach. Existing literature focuses on "fairness" as the rationale for having high standards of proof in criminal trials. Absent of these considerations, the implication of standard models would be that the legal system should minimize the sum of judicial errors and this would be incompatible with the current legal practice. This paper contributes to the interpretation of the standard of proof in criminal trials in two ways. First, it provides a utilitarian explanation as to why there are asymmetric costs associated with false convictions and acquittals. It relies on the fact that non-criminals may engage in costly and precautionary activities in order to decrease the probability of false convictions. Second, it shows that this difference in the costs associated with false conviction and acquittal rates is under certain circumstances sufficient to justify hightened standards of proof.