Such an account could contain the identity or identities of the people who were involved in the event, a narration of how the incident, itself, occurred, and a detailed description of the scene before, during, and after the event took place. In criminal cases in the United States, the general tendency is for juries to grant EWT a rather high level of reliability, especially in the process of identifying the perpetrator/s of a criminal act (McLeod).
Unfortunately for jurists, research has been consistent in showing that EWT is not as reliable as generally perceived. As a matter of fact, in Problems and Materials on Trial Advocacy written by A. Leo Levin and Harold Cramer, the authors stated that
Eyewitness testimony is, at best, evidence of what the witness believes to have occurred. It may or may not tell what actually happened. The familiar problems of perception, of gauging time, speed, height, weight, of accurate identification of persons accused of crime all contribute to making honest testimony something less than completely credible (Cline).
This view is shared by many legal practitioners. The prevailing view not only among defense lawyers but also among prosecutors is that in spite of the sincerity of eyewitnesses, EWT could not always be credible. They are convinced that when somebody professes to have witnessed an incident or a crime, for that matter, such a statement should not be taken by faith because it is very possible that what he or she remembers seeing may not have actually happened.
This argument is generally based on the fact that not all eyewitnesses possess the same degree of competence. A competent eyewitness should have the following qualities: sufficient “powers of perception”; ability to remember and describe what he or she remembers seeing; and the willingness to tell only the truth (Cline).
In theory, an eyewitness testimony could be discredited in a court of law if it could be established that an eyewitness is not competent by showing that his or her memory and perception are impaired, he or she has certain biases or prejudices against the accused, or that he or she is a reputed liar. Unfortunately, records show that even eyewitness accounts from highly competent witnesses have nonetheless caused the conviction of many innocent people. These are cases which involve competent eyewitnesses giving eyewitness accounts which are not credible but appear convincing to jurors (Cline).
Since eyewitness account is highly dependent upon the memory of an individual, his or her recollection of events is greatly affected by “age, health, personal bias and expectations, viewing conditions, perception problems, later discussions with other witnesses, [and] stress” (Cline).
In other words, EWT should be appraised on a case-to-case basis, taking into consideration the personal attributes of the eyewitness and the conditions prevailing at the time of the event such as weather condition, time of day, distance of the witness from the incident, and illumination. Stress is another factor which affects a person’s memory. For instance, an eyewitness who has been so horrified by a killing often fails to recall vital aspects of the incident. In such cases, it is said that the memory of the witness fails him or her, giving credence to the school of thought which maintains that man’s memory is actually imperfect (Cline).
Elizabeth Loftus belongs to this school of thought. In fact, in her book Memory: Surprising New Insights into How We Remember and Why We Forget, she wrote that “we often do not see things accurately in the first place. But even if we take in a reasonably accurate picture of some experience, it does not necessarily stay perfectly intact in memory…
With the passage of time, with proper motivation, with the introduction of special kinds of interfering facts, the memory traces seem sometimes to change or become transformed” (Cline). In other words, memory is not only imperfect but could also be manipulated or managed. This is only one of many observations raised by scholars and researchers about the reliability of eyewitness testimony.