The effect of confession evidence on conviction, and considering alternative scenarios as remedy in a sample of police officers

In order to prevent tunnel vision and ultimately miscarriages of justice, police, prosecutors and judges must remain open to alternative scenarios in which the suspect is in fact innocent. However, it is not evident from the literature that people are sufficiently aware of how alternative scenarios should be employed in the decision making process. In the present research, 230 Dutch police officers read one of three versions of a case description. In the first version, there was strong evidence against the primary suspect. In the second version, the suspect additionally confessed, increasing the body of incriminating evidence. In the third version, the suspect confessed, but before deciding on their conviction, participants were instructed to consider how well each piece of evidence fitted in the primary but also in the alternative scenario (in which the crime was committed by an alternative suspect). Contrary to expectations, the confession did not increase conviction and the alternative-scenario consideration did not suppress conviction. Implications of these null findings are discussed.