Recent events highlight limitations of eyewitness testimony

Research shows that variables at the crime scene and police identification protocols can influence eyewitness memories, which may already be questionable.

Lancaster residents who followed the recent trial in Ferguson may have observed that the accounts of eyewitnesses, from bystanders to the police officer who stood trial, varied greatly. According to Newsweek, witnesses perceived different facial expressions and interactions, possibly because these are open to interpretation; however, eyewitnesses also reported different physical movements and actions, a discrepancy that is less easily explained. Unfortunately, such inconsistency on the part of eyewitnesses is not abnormal.

When a person is charged with a crime and tried, eyewitness testimony can seem highly credible and convincing. Unfortunately, research shows that eyewitness errors are not uncommon, and these mistakes may impact many criminal cases.

Flawed perceptions and memories

The Innocence Project states that eyewitness mistakes are the leading known cause of wrongful convictions in America. Eyewitness testimony has supported 72 percent of convictions that were later proven wrong through DNA testing.

Various factors can undermine the accuracy of an eyewitness. Estimator variables at the scene of the crime may prevent the witness from adequately viewing the incident. Stressors, such as the presence of a deadly weapon, may distract witnesses and prevent them from accurately perceiving what is happening. System variables during police identification procedures may also subtly influence witnesses.

Even when witnesses have ideal viewing conditions and police follow proper protocols, the nature of human memory remains problematic. What a person sees when he or she witnesses an event is not necessarily the same as what actually happens. There also may be discrepancies between the way a person initially perceives an event and the way he or she remembers it later.

Report calls for change

According to Time magazine, in October, the National Academy of Sciences released a report based on an analysis of over three decades of research into eyewitness accuracy and errors. The report highlighted the limitations of eyewitness testimony and recommended that authorities update lineup procedures to reduce the risk of authorities influencing eyewitnesses. The recommendations include the following changes:

  • Recording the entire lineup process to ensure poor practices on the part of authorities or hesitation on the part of the eyewitness can be seen later.
  • Developing standardized eyewitness instructions to reduce the risk of authorities influencing the eyewitness's choice.
  • Asking eyewitnesses to state their confidence in the identification immediately after making it, rather than later, when confidence may be inflated.
  • Requiring people who are not aware of the suspect's identity to conduct lineups to reduce the risk of intentional or unwitting influence on the eyewitness.

In 2013, a Pennsylvania senator introduced a bill to implement several of these changes. The bill requires authorities to conduct blind lineups, whenever reasonably possible, and give eyewitnesses standardized instructions stating that the suspect may not be present in the lineup. The bill also stipulates that authorities must withhold confirming feedback until an eyewitness officially identifies a suspect, and they must take a confidence statement once the identification is made.

If this bill or a similar measure passes, the risk of eyewitness errors during Pennsylvania criminal cases may be significantly reduced. Still, research into eyewitness testimony and human memory suggests that the problem of eyewitness accuracy may never be fully resolved.

Anyone facing criminal charges involving eyewitness testimony should speak with a criminal defense attorney about challenging this evidence and the associated charges.

Keywords: eyewitness, evidence, crime, arrest