The Bias Expert Witness: R v Thomas Edison
By Kate Jurgens, University of New Brunswick
In 2015 the New Brunswick Court of Queen’s Bench held a pre-trial motion for R v Edison during which the independence and impartiality of the Crown’s expert witness was called into question.[i] The defence sought to have the evidence excluded on the grounds that the expert was bias. This commentary provides an overview of the landscape of expert evidence admissibility in Canadian case law, in particular in light of R v Edison and White Langille, a recent Supreme Court decision which departs from previous jurisprudence.
In the years since Mohan there has been much disagreement among lower courts as to the role bias plays in the admissibility of expert evidence.[ii] An examination of the jurisprudence reveals that two schools of thought have developed. The first views independence and impartiality as a stand-alone criterion that must be met as a threshold requirement in order to have expert evidence admitted. This view is reflective of the traditional categorical approach, which lacks flexibility but has the benefit of providing structure and predictability to the law. The second considers independence and impartiality to be a matter addressed under judicial discretion to assess the probative value of the evidence in relation to its prejudicial effect. This view is representative of the principled approach, which offers more flexibility but lacks predictability. Ferguson J in Edison stressed the latter approach as a means to address the independence and impartiality of expert witnesses, ultimately holding that a trial judge should consider the weight that independence and impartiality holds when balancing its prejudicial effect against the probative value of the testimony.
The true value of Edison lies in Justice Ferguson’s analysis of the role of judicial discretion in ensuring that an expert witness is independent and impartial. Edison adds to Canadian case law through its expansion of the role of judicial discretion for expert evidence and, in doing so, moves evidence law further towards a principled approach. The decision in Edison is illustrative of the shift away from the rigid rules-based approach towards a flexible principled approach. While Mohan remains prominent, Edison expands the role of judicial discretion by stating that the residual power held by the judge should be the focus of the analysis in determining the independence and impartiality of expert evidence. This shift allows for a contextual approach, thus keeping the accused’s right to a fair trial at the forefront of the analysis.
In the months following Edison the Supreme Court addressed this very issue in Burgess Langille Inman v Abbott and Haliburton [White Langille].[iii] The Court held that an expert must acknowledge that their primary duty is to provide unbiased evidence to the court. This effectively creates a threshold requirement which the expert must meet in order for their testimony to be admissible. This decision does not conform to the general trend seen in recent years and is more characteristic of the categorical approach in which admissibility was addressed as a threshold matter, rather than as an exercise of judicial discretion.
Jurisprudence on expert evidence admissibility has over time shown a marked departure from the categorical approach towards a principled approach focused on flexibility and case-by-case analysis. Edison is an important contribution to this area of evidence law for its continued evolution towards the principled approach in holding that when the independence and impartiality of an expert is called into question, the core focus of the analysis should lie in judicial discretion. Edison builds upon earlier jurisprudence, but White Langille breaks from this trend and the two appear to be irreconcilable. Edison is representative of the modern principled approach in which judicial discretion is applied to balance the probative value against the prejudicial effect of the evidence, while White Langille applies a categorical analysis in which a threshold requirement is added to the Mohan test as a matter of admissibility.
Prior to the Supreme Court’s recent decision in White Langille lower courts closely followed the Mohan test, Edison is representative of this trend. These contradicting decisions indicate major change in the years to come. Edison appeared to be a beacon for the expansion of judicial discretion when independence and impartiality were called into question. In light of White Langille it seems as though Edison would now be decided differently.
[i] R v Thomas Edison  NBQB 074
[ii] R v Mohan  2 SCR 9
[iii] White Burgess Langille Inman v Abbott and Haliburton  2 S.C.R. 182
Evidence expert testimony witness