The police play an important role in the criminal justice system - they are the principal investigators of crime and the main source of the evidence used by the prosecution to secure a conviction. Since the police play such an important role in our system, it is not surprising that how the police investigation is conducted greatly affects the outcome of the trial.

A significant element that has been identified in many cases of wrongful conviction is tunnel-vision in the police investigation. Tunnel-vision refers to a situation where the police become convinced of the guilt of a particular suspect, and in focusing on that suspect ignore other legitimate avenues of investigation. When tunnel-vision occurs, the police will focus on evidence that implicates the suspect they have focused on, while discounting evidence that may indicate the innocence of that suspect (also known as "confirmation bias"). In addition, in some cases police misconduct and illegality contributes to the problem.

Tunnel-vision tends to arise most often in the context of particularly heinous crimes, where there is a high level of public pressure on the police to secure a suspect. This intense pressure can force the police to prioritize efficiency over procedure, and in the process mistakes are made.

Tunnel-vision can also arise in a number of other ways. For example, police may tend to focus on an individual in the area who is known to have a prior criminal record (or is otherwise already known to the police). Since this individual has committed wrongdoing in the past, it is easy to assume that they are likely to be responsible for the current crime being investigated.

It bears mentioning to say that police do not necessarily engage in willful misconduct in cases of tunnel-vision. On the contrary, police are interested in apprehending the right suspect - the conviction of an innocent person is not their goal. Confirmation bias is a natural human desire to prove our theories correct. However, given its known role in wrongful convictions, it is necessary to examine the phenomenon and attempt to develop procedures that will minimize the likelihood of its occurrence.

[prepared by Moheb Tewfik, class of 2008]

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