System Variables

Those factors that can directly influence the accuracy of the identification process and are directly under the control of the criminal justice system are referred to as system variables. This is in contrast to estimator variables, such as lighting, distance, and stress, that cannot be controlled after the incident. These variables are called system variables because the criminal justice system has control over them. System variables can be separated into two stages: (1) pre-lineup procedure and (2) lineup procedure. This chapter focuses on pre-identification system variables. Some examples include the type of post-event information provided to the witness, the way investigative interviews are conducted, and exposure to mugshots. In this chapter, we review these variables and how they influence the subsequent identification.