Guilty as Labeled — Can we Count on Expert Witnesses?
Alcoholic. Honours student. Naïve. Illegal immigrant. Wealthy. Canadian. Stupid. Slow. Male. Healthy. Sister. Lazy. Parent. Obese. Autistic. Sex offender. Psychopath. Take a moment to think of all labels that define you or have been subjected to.
We live in an age of labels. Not only do we make consumption decisions based on name or designer brands for just about everything these days (e.g. I often eat foods labeled as ‘healthy,’ despite that being the case or not), we are also defined by our labels. Notably, labels provide useful information and function to create order in our hectic lives by reducing our uncertainty about things and people. These categories serve an adaptive function, allowing us to interact and navigate in the overwhelming complexity of our environments. On the other hand, labels can be inherently limiting to our potential as human beings. We are viewed through an external lens, subject to inalterable and inseparable labels. As I will illustrate below, some labels cause more harm than others.
All too often, the label of a psychological disorder diminishes an individual’s self worth as he or she embodies a stigmatized identity. Even more, certain diagnostic labels such as “psychopath” may serve as the “kiss of death” for those in the court systems. Prosecutors have used Hare’s Psychopathy Checklist-Revised (PCL-R) as ammunition when determining future risk of individuals in society: juveniles labeled as psychopaths are more likely to face transfers and harsher punishment in adult court, capital murder defendants labeled as psychopaths are more likely to be sentenced the death penalty, and sex offenders labeled as psychopaths are more likely to be preventatively detained.
The rigor and reliability of psychological tests in real-world settings is of fundamental importance as expert opinions and evidence from medical, behavioural science and forensic mental health experts (i.e. psychologists and psychiatrists) are becoming increasingly more prevalent in the judiciary system. These tests often have the ability to influence jurors’ opinions and as a result, directly determine the fate of the offender on trial. Remarkably, forensic assessment tools (including the PCL-R) maintain high inter-rater reliability in laboratory settings; however, do expert witnesses in legal proceedings fail to remain objective and unconsciously sway their opinion to match the opinion of the particular side that hires them?
This is exactly what Murrie & Baccaccini sought to answer. It turns out the answer is yes! For this study, they recruited more than 100 practicing, PhD forensic psychologists/ psychiatrists to participate in a large scale forensic consultation (they were blinded to the fact they were in an experiment, were paid $400 per day, and were randomly assigned to either a prosecution-allegiance or defense-allegiance group). On average, prosecution experts scored the PCL-R (which is out of 40) around 3 points higher than did the defense experts (difference was greater than expected as outlined in rater agreement values in instrument manual). In other words, simply working within this oppositional context caused rival evaluators to form significantly different attitudes toward the same defendant (scoring trends correlate systematically with the side the expert witness is testifying for).
Given this “adversarial allegiance,” psychologists acting as forensic experts need to clearly explain the subjectivity of the PCL-R when it is used as evidence in court. Combining the lay understanding of psychological assessment in which one believes that expert opinion is binding/definite with the fact that the data is based on allegedly objective instruments and procedures (scoring and interpretation of standardized tests) may unintentionally bias the result of court proceedings. Thus, the reliability of the psychological test must be accurately outlined beforehand.
If this catches your interest, I highly suggest checking out the original article! http://www.annualreviews.org/doi/pdf/10.1146/annurev-lawsocsci-120814-121714
