How Courts Evaluate Eyewitness Testimony

In the justice system, eyewitness testimony plays an important role in the determination of guilt. Jurors trust the firsthand accounts of people who experienced the event, and lawyers love to use that trust. Unfortunately, human memory is imperfect and eyewitness testimony does not always provide the unquestionable proof people expect.


An eyewitness is someone who was present at the incident, presumably watching the events transpire. Jurors trust these witnesses, because a firsthand account often seems more credible than hearsay or presented pieces of evidence. If a person was present, saw what happened, recalled it clearly, and answered under oath, why shouldn’t the jury trust that person’s information? While eyewitness testimony can seem very compelling and recount a witness’s honest recollection, it does not always serve as the most accurate evidence in a case.


Humans are subjective creatures. Our genetics and experiences come together to give us each a unique worldview. Two people can listen to the same piece of music or watch the same play and each remember completely different experiences. This subjectivity can change an eyewitness’s interpretation of an event and distort the account in the courtroom. Consider other factors that can inhibit testimony accuracy:

  • Stress. Stress changes brain and body chemistry. When the adrenaline starts pumping, witnesses may zero-in on one or two key features of the incident for example, or remember everything in a blur. Current psychological understanding of the role of stress on performance indicates that performance increases with minor stress; but, after a point, dramatically decreases. When applied in the courtroom, this suggests that high stress situations may alter an individual’s ability to accurately reconstruct a memory.
  • Preconceived notions. Everyone carries biases. While many people try to remain as objective as possible, conscious and unconscious biases affect the way people interpret life experiences. These biases or preconceived notions can infiltrate memories and lead a witness to make certain judgments about a person, the environment, or the events that took place.
  • Suggested alternatives. Humans do not simply playback recordings of memories in their minds. They reconstruct them based on information stored within the memory. As a reconstruction, memories are vulnerable to the power of suggestion. If a witness watches a movie or talks to an investigator, the new information he or she hears can influence the reconstruction of a memory. Small alterations to the memory can completely change an eyewitness’s account. Witnesses may combine memories or make changes based on what they see and hear after the event.
  • The presence of firearms or other weapons. In crimes involving weapons, many witnesses may focus on the weapon instead of perpetrator. Later, they may think they remember enough details to identify a criminal, even if they didn’t really get a good look.

Human memories are fickle, and change as a person experiences new and different stimuli. Memories help confirm and corroborate facts of a case, but they often fail to provide compelling evidence on their own.


Those involved in the criminal justice system can take steps to corroborate and confirm eyewitness testimony to reduce the likelihood of a false memory interfering with the outcome of a case. The reliability of an eyewitness testimony may improve if investigators:

  • Use double blind procedures. During suspect identification proceedings, neither the suspects nor the directing investigators should know anything about the case. The witness should not receive any feedback that may interfere with the selection process.
  • Corroborate facts with testimony. Attorneys on both sides should look for connections between witness testimony and the hard evidence of a case to confirm the memory.
  • Consider confidence ratings. Investigators may want to ask eyewitnesses about their confidence levels regarding memory, suspect identification, and the circumstances of the case. Highly confident witnesses often have a more accurate memory of the events than less confident witnesses.

Increased awareness of the potential problems with eyewitness testimony can change the way juries think about a case. Those who scrutinize the evidence and testimony can more confidently evaluate the facts and avoid sending an innocent person to prison.