The Psychopathy Checklist (PCL) is a research rating scale developed by Robert Hare and his colleagues for the assessment of the clinical construct of psychopathy in criminal populations. Before the development of the PCL, the construct of psychopathy was well known to many mental health professionals, but determining what specific traits and behaviors contributed to a diagnosis was not easily established or agreed upon, making research into the construct difficult. The PCL, largely influenced by the clinical observations of American psychiatrist Hervey Cleckley, provides a list of personality and behavioral characteristics that are rated on presence and severity in the offender being assessed. Research was thus made possible into the construct of psychopathy. The PCL gave a quantifiable score and formed a common assessment measure ...