Overstepping and Sidestepping: The Expert Evidence Dance

Abstract

As science learns more about the world, few areas remain beyond its reach. Expert scientific evidence can be central to cases as varied as medical malpractice, the safety and efficacy of drugs and chemicals, the use of blood tests to determine paternity, or the interpretation of DNA findings. But this evidence can be as perilous as it is necessary. The very quality that renders expert evidence necessary, namely, that it is outside the fact-finder’s ken, also gives rise to the danger: that it will in some way be misunderstood or improperly applied. I will argue that more should be done to protect against the danger. My suggestion is this: questions for scientific experts should be framed by the court before the trial begins. This idea builds on the requirement in R. v. Abbey, 2009 ONCA 624 to delineate the nature and scope of expert evidence prior even to considering the Mohan criteria of admissibility. It is a requirement that receives no explicit mention in the Supreme Court of Canada’s most recent decision on expert evidence in White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23. However, the problematic treatment of expert DNA evidence in the recent case of R. v. Awer illustrates why this requirement must not be overlooked. Where the court passively accepts the expert evidence offered by the parties, the evidence can easily overstep or sidestep key issues. This is a risk that exists in all cases involving expert evidence, whether criminal or civil, by jury or judge alone. And it is a risk to which judges, lawyers and experts should all be alive. One practical way to guard against this risk would be to require the court to frame questions for scientific experts in advance of the trial.