Investigating the role of the Psychopathy Checklist–Revised in United States case law.

Abstract

Although the Psychopathy Checklist-Revised (PCL-R; Hare, 2003) appears to be the most widely used measure of psychopathic traits in forensic settings around the world, relatively little is known about how often it is introduced into legal cases and the types of cases in which it is being used. DeMatteo and Edens (2006) first summarized the extant U.S. case law on the PCL-R, identifying 87 cases in which it had been introduced since its publication in 1991 through 2004. Using an identical search strategy employed in the earlier review (LexisNexis legal database), we identified 348 cases involving the PCL-R from 2005 through 2011. Notably, the PCL-R appeared to be primarily a “prosecution tool” in these cases in that it was rarely first introduced into evidence by the defense. In most cases it was used to assess offenders with significant histories of violence in the context of risk assessments—with resulting risk statements being strongly associated with the results of the PCL-R evaluation (i.e., high psychopathy equating with high recidivism risk, low psychopathy equating with low recidivism risk). Challenges to the admissibility of PCL-R evidence in these cases were rare and typically unsuccessful, even though some assertions, particularly in relation to the PCL-R's predictive validity, appeared to have questionable scientific support. On average, prosecution examiners reported PCL-R scores that were 7 points higher than defense examiners. We discuss these findings in the context of the appropriate roles for the PCL-R in court and its potential for misuse when evaluating psycho-legal issues.