No Safeguard on Duty: Expert Evidence in Aquatic Death Cases

Abstract

When a person dies by drowning, expert opinion evidence can assist the trier of fact with understanding key issues such as the time, medical cause, and manner of death. At the same time, there are well-documented risks that triers of fact may not be properly equipped to scrutinize expert methods and qualifications, or they may give expert opinions more weight than they should. For drowning deaths, an inequality of resources between the Crown and the accused may make this specialized area inaccessible for defence counsel prior to a trial, when an accused person is faced with the decision to plead guilty. In this paper we review the scientific literature and compare it to principles that have been recognized in reported decisions on drowning deaths to see if the concepts adopted by the courts reflect established science. While most experts in our sample met standards of practice, in a limited number of cases unsound science was deemed to be admissible in the pre-trial voir dire, after which accused persons pleaded guilty. These findings shed light on a different, but just as dangerous, misuse of expert evidence as a tool to extract guilty pleas before they can be properly tested during a trial. We conclude that the current legal test does not eliminate the risks of expert opinion evidence, rather, it shifts it from the triers of fact to those accused of committing crimes, offering them insufficient protection when they are in a particularly vulnerable position. In this way, drowning deaths provide an example of the ways expert evidence can be used problematically in other factual contexts.