Eyewitness Testimony and Identification Tests
Donald M. Thomson Edith Cowan University
With few exceptions, eyewitness testimony constitutes a major part in a criminal trial. The account of an eyewitness as to what he or she observed may be sufficient for the tribunal to conclude that the accused was the person who committed the particular act and that that act was intentional. Given the pivotal role of eyewitness testimony in establishing that an offense was committed, and that the accused was the offender, it is important to identify circumstances that impair or restrict eyewitness testimony so that investigatory procedures that improve the quality of testimony can be instituted. The completeness and accuracy of eyewitness testimony and identification is a function of many factors, some of which are under the control of the police and legal investigator and some of which are not (see Wells, 1978). By being aware of the controllable factors the police investigator can conduct the investigation in ways that enhance the quality of the eyewitness testimony. By being aware of the uncontrollable factors that may affect the eyewitness account, the investigator will be able to appreciate the limitations of that testimony and to assess its credibility. It is useful to distinguish three stages that underlie eyewitness testimony. The first stage is the observation stage. This stage sets the limits of the completeness of the eyewitness' testimony. The second stage is the retention stage, and the third stage is the narration stage. Factors operating during the retention and narration stages (e.g., media reports describing the critical event, the form and number of police interviews) will further constrain the completeness and accuracy of the testimony. Some factors have their impact on eyewitnesses solely at one stage, for example, visibility of offender at the observation stage; other factors impact at more than one stage, for example, stress. From this analysis of testimony it follows that the factors operating during the observation stage are outside the control of the police investigator.