Practitioners agree that criminal discovery rules have important effects both on how cases develop and on how they get resolved. However, there has been little empirical work done to measure the nature and breadth of these effects. This paper seeks to fill that gap by presenting a statistical analysis of the criminal discovery rules and case outcomes in two similarly situated jurisdictions. First, this paper analyzes theoretical predictions about the effects of criminal discovery rules and initially agrees with the views of many practitioners: increased disclosure should lead to shorter cases. Then, to analyze this hypothesis, the paper presents a new dataset of 200 criminal cases that tracks the charged crime, attorney experience and background, attorney pay structure, bail status, and other variables that could impact case outcomes. The dataset measures and compares these variables across two jurisdictions that use different criminal discovery rules but are otherwise quite similar. Finally, the paper presents the results of this analysis, concluding that strict disclosure rules impose significant costs on legal systems. Specifically, the statistical analysis suggests that the Manhattan court system could save resources by mandating more liberal discovery practices. This policy shift would have the important added benefit of increasing fairness for criminal defendants.