Role-Induced Bias in Court: An Experimental Analysis


Correspondence to: Christoph Engel, Max Planck Institute for Research on Collective Goods, Kurt-Schumacher-Str. 10, D-53113 Bonn, Germany.



Criminal procedure is organized as a tournament with predefined roles. We show that assuming the role of a defense counsel or a prosecutor leads to role-induced bias even if participants are asked to predict a court ruling after they have ceased to act in that role and if they expect a substantial financial incentive for being accurate. The bias is not removed either if participants are instructed to predict the court ruling in preparation of plea bargaining. In line with parallel constraint satisfaction models for legal decision making, findings indicate that role-induced bias is driven by coherence effects, that is, systematic information distortions in support of the favored option. This is mainly achieved by downplaying the importance of conflicting evidence. These distortions seem to stabilize interpretations, and people do not correct for this bias. Implications for legal procedure are briefly discussed. Copyright © 2012 John Wiley & Sons, Ltd.