Posted on the Innocence Project Blogsite By: Keith Findley, Co-Director of the Wisconsin Innocence Project
The 160-plus post-conviction DNA exonerations of the last 15 years have exposed numerous problems that have contributed to convicting the innocent. One commonality in almost all of the cases, however, is that they feature some form of tunnel vision.
Tunnel vision is a natural human tendency with particularly pernicious effects in the criminal justice system. Tunnel vision is the process that leads investigators, prosecutors, judges, and defense lawyers alike to focus on a particular outcome, and then to filter all evidence in a case through the lens provided by that outcome. Through that filter, all information that supports the adopted outcome is elevated in significance, viewed as consistent with the other evidence, and deemed relevant and probative, while evidence inconsistent with the chosen theory is easily overlooked or dismissed as irrelevant, incredible, or unreliable.
Tunnel vision both affects, and is affected by, other flawed procedures in the criminal justice system. Mistaken eyewitness identifications, for example—the most frequent single cause of wrongful convictions— can convince investigators early in a case that a particular individual is the perpetrator. Police and prosecutors, convinced of guilt, might recruit or encourage testimony from unreliable jailhouse snitches, who fabricate stories that the defendant confessed to them, in hopes that they will benefit in their own cases from cooperation with authorities. Or forensic scientists, aware of the desired result of their analyses, might be influenced—even unwittingly—to interpret ambiguous data to support the police theory, or worse, fabricate results. All of these additional pieces of evidence then enter a feedback loop, bolstering the witnesses’ confidence in the reliability and accuracy of their incriminating testimony, and in turn reinforcing the original assessment of guilt held by police, and ultimately prosecutors and courts.
Tunnel vision typically begins in the initial stages of criminal cases—during the police investigation. But tunnel vision is in fact more pervasive than that; it infects all phases of criminal proceedings, beginning with the investigation of cases, but then proceeding also through the prosecution, trial or plea-bargaining, appeal, and post-conviction stages.
Tunnel vision is a well-recognized phenomenon in the criminal justice system. Most of the official inquiries into specific wrongful convictions have noted the role that tunnel vision played in those individual cases of injustice. For example, former Illinois Governor George Ryan’s Commission on Capital Punishment, the Innocence Commission for Virginia, and official Canadian governmental inquiries, among others, have all identified tunnel vision as a significant problem in the cases in which an innocent person was wrongly convicted.
In some ways the criminal justice system demands or teaches tunnel vision overtly. For example, police are widely taught that, once they believe a suspect is guilty, they should interrogate the suspect by shutting down all denials of guilt and employing psychological tactics designed to achieve a single goal: a confession. And court rules make it difficult to present evidence of alternative, third-party suspects, or to introduce new evidence of innocence once a conviction has been obtained. Each of these processes can contribute to injustices when they contribute to focusing on an innocent person and unwillingness to consider the guilt of the true perpetrator.