Expert Evidence About Violence Risk Assessment: A Study of Canadian Legal Decisions

Abstract

In recent decades the practice of violence risk assessment and use of violence risk assessment instruments has become widespread in the criminal justice system. How are courts reacting to these developments? Herein the findings of a survey of Canadian case law are reported. Using Quick Law 35 cases were systematically identified in which judges commented on expert evidence regarding violence risk. Judicial comments were summarized with respect to evaluator qualifications, assessment procedures used, and presentation of findings and opinions. Findings indicate a wide variety of judicial preferences including the skill and knowledge of the evaluator, the type of information used, the description of findings and procedures, and the applicability of legal rules. Although potentially useful to evaluators caution is urged regarding the incorporation of some judicial preferences.

Keywords:

• Violence risk assessment report
• criminal court
• police
• expert evidence
• expert witnesses

Acknowledgments

The authors gratefully acknowledge the assistance of David R. Lyon in guiding the legal research. The opinions presented herein are those of the authors and do not necessarily reflect those of any agency or organization.

Notes

The absence of cases from Québec is notable given that it is the second most populated province in Canada. The most likely explanation for this is that most rulings from Québec are in French and thus would not have been picked up by the English search terms used.

An override is when an evaluator alters the final risk determination of a violence risk assessment instrument. For instance when a moderate risk is indicated by the instrument total score but the evaluator increases the risk to high based on their professional judgement.