Judges versus jurors: Biased attributions in the courtroom

The fundamental purpose of a tort trial is to allocate responsibility. However, attributing fault is difficult, and decades of research in psychology have shown that human beings are prone to make systematic errors in performing this task. What can be done about this? The United States and countries in continental Europe adopt diametrically opposed strategies to reduce errors in the attribution of responsibility in the courtroom. American law delegates fact-finding to jurors and makes some type of evidence inadmissible in court to protect jurors from potentially biasing information, such as character evidence. European legal systems, instead, employ almost exclusively judges to perform fact-finding and allow character evidence at trial, under the assumption that judges are better than laypeople in weighing the probative value of this type of evidence. There is a longstanding debate among legal scholars on whether the American or the European approach reduces more trial errors, but the relative performance of the two legal systems remains largely untested. This article is the first to provide evidence on the relative performance of these two systems. Our results suggest that jurors fail to correctly apply European rules of character evidence. The American rules on the inadmissibility of character evidence seem therefore a more appropriate choice when fact-finding is performed by jurors. We find also that, contrary to jurors, judges apply European rules correctly and thus reduce the risk of errors in the attribution of responsibility. Overall, this result indicates that the American and the European evidence rules to improve fact-finding are well set up. Nonetheless, we also find that neither of the two systems is able to prevent factfinders' errors in the attribution responsibility when these mistakes are not due to the type of evidence presented at trial but to (unconscious) beliefs held by factfinders themselves. We thus propose a set of policies that could improve factfinders' ability to avoid mistakes in attributing responsibility.