The construct of psychopathy has had an extensive history, and clinicians and researchers have generally agreed on the defining features of psychopathy. Despite this agreement, prior to the development and formal publication of the Hare Psychopathy Checklist (PCL; Hare, 1980, 1991, 2003) and related measures, there were no generally accepted and widely used methods for evaluating psychopathic behavior. This meant that the field was not accumulating a consistent body of knowledge with reproduceable research findings. We present historical conceptualizations of the disorder, discuss the broader clinical-forensic and legal contexts at the time when the Psychopathy Checklist was being developed, and highlight theoretical and practical needs for constructing an accepted measure of psychopathy based on these historical conceptualizations. We talk about the different procedures that Dr. Hare and his students have used across the years to evaluate psychopathy, which culminated in the development of the Hare Psychopathy Checklist-Revised (PCL-R; Hare, 1991, 2003). The introduction of the PCL moved the construct of psychopathy from being a poorly understood and not well researched personality disorder to one of the best validated clinical constructs in psychopathology.
