Research continues to reveal risks inherent to using eyewitness evidence

Research indicates that eyewitness errors are almost inevitable, given the nature of memory, which makes caution essential in cases that use this evidence.

Human memory is usually idealized as clear, accurate and enduring. Not surprisingly, evidence from eyewitnesses often carries unique weight in criminal cases. However, research increasingly shows that memory is not flawless, and neither is eyewitness testimony. According to the Innocence Project, over 70 percent of wrongful convictions involve eyewitness errors. As a result, it is critical for this evidence to be treated with caution during criminal cases in St. Louis.

Shortcomings of human memory

According to The Washington Post, in 2014, the National Academy of Sciences issued a report after reviewing 30 years of research into eyewitness identifications. The report stresses the fact that memory is imperfect and often prone to distortion. Even recollections of traumatic and presumably memorable events, such as alleged sex crimes or violent criminal offenses, can be inaccurate.

There are many reasons that eyewitness memories can become warped by the time an eyewitness makes an official identification or testifies in trial. During an alleged crime, factors such as lighting acute stress, and weapon focus, among many others may prevent an eyewitness from making accurate observations. Over time, as eyewitnesses recall the alleged crime or receive other information, their memories may change to accommodate new feelings or knowledge. In addition, comments made by police officers at any identification procedure can reinforce false memories. For example, if the officer tells the person that the perpetrator is in the line-up or photographic array, the identification may be channeled more to a "who looks the closest to the perpetrator" rather than an actual identification.

Many of the factors that give rise to inaccurate eyewitness memories are uncontrollable. However, law enforcement identification protocols can also play a role in biasing eyewitnesses or undermining the accuracy of their memories. Therefore, the report recommends that authorities use caution with eyewitnesses and implement set procedures to reduce the risk of memory contamination.

Steps to prevent eyewitness errors

Based on the studies reviewed, the NAS report suggests several specific changes to eyewitness identification procedures. These changes include:

  • Requiring blind lineups, or lineups in which the participating officers do not know the identity of the suspect
  • Advising the witness that the suspect might not be in the lineup and that an identification will not stop the official investigation
  • Recording the full lineup procedure so that it can be reviewed later if necessary
  • Requesting that the eyewitness describe his or her confidence in the identification immediately, before any positive feedback is given

Unfortunately, many of these legislative changes have not yet been implemented in Missouri. The Missouri Supreme Court is considering adopting a jury instruction to make sure that Missouri juries are aware of the dangers and pitfalls inherent in this testimony. In 2014, state lawmakers considered a bill that would have required all of these measures whenever practicable for people facing state criminal charges. The legislation also would have mandated other protective steps, such as the use of lineup fillers who reasonably resemble the suspect. Unfortunately for people facing criminal accusations in the state, this bill failed to pass.

Without these measures in place, the potential for eyewitness errors and associated harmful outcomes, such as wrongful convictions, may remain high. Considering this threat, anyone facing charges that hinge on eyewitness evidence should think about speaking to an attorney about defending against those charges.