Supreme Court clarifies requirement of independence of expert witnesses

01 May 2015

It is well-established in Canadian law that expert witnesses have a special duty to the Court to provide fair, objective and non-partisan assistance. Courts have disagreed, however, on how and when to deal with concerns raised about the independence of expert witnesses — should independence and impartiality be considered at the threshold admissibility stage, or only in the weight given to the evidence? 

In White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23, the Supreme Court of Canada has clarified that independence concerns should be considered at the threshold admissibility stage, but that threshold requirement is not onerous: the expert must simply be aware of his/her primary duty to the Court and able and willing to carry it out.

Case overview

The facts of the case are relatively simple: a group of shareholders retained a new accounting firm, Grant Thornton LLP, to perform various accounting work regarding their company. Grant Thornton’s work revealed what the shareholders say was negligent work performed by the company’s former accountants. The shareholders commenced an action in professional negligence against their former accounting firm.

The shareholders brought a summary judgment motion supported by a report of a forensic accounting partner at Grant Thornton. The defendants applied to strike the partner’s affidavit on the basis that she was not an impartial expert witness because the claim was essentially about a difference of opinion between two accounting firms and Grant Thornton, as the firm that discovered the alleged irregularities, had a financial interest in the outcome of the litigation and, as a partner, the witness had a personal financial interest.

The trial judge struck the expert’s affidavit in its entirety on the basis that the expert “must be, and be seen to be, independent and impartial." The majority of the Nova Scotia Court of Appeal found the trial judge erred in law and that the affidavit should not have been struck. The Supreme Court of Canada agreed with the Court of Appeal.

The Supreme Court's decision

The Supreme Court restated and clarified the two-stage test for admissibility of expert opinion evidence as follows:

  1. the evidence must meet four threshold admissibility issues:
    1. relevance:
    2. necessity in assisting the trier of fact:
    3. absence of an exclusionary rule:
    4. a properly qualified expert; and
  2. if the first step results in a conclusion that the evidence is admissible, the judge may still exclude evidence on the basis of a cost-benefit analysis which determines whether the evidence “is sufficiently beneficial to the trial process to warrant its admission despite the potential harm to the trial process that may flow from admission.”

Justice Cromwell of the Supreme Court concluded that there are three related concepts which comprise the duty of expert witnesses: impartiality, independence, and absence of bias. An expert must provide evidence that is objective, the product of the expert’s independent judgment, and does not unfairly favour one party’s position over another.

Concerns about independence and impartiality are properly considered both under the qualified expert branch of the threshold admissibility test and in the second-stage cost-benefit analysis. At the threshold admissibility stage, the standard is not onerous: is the expert aware of his/her primary duty to the court and able and willing to carry it out? Absent a challenge, the expert’s attestation or testimony to this effect will be sufficient to satisfy the admissibility threshold.

The Court gave some useful information about factors that could render evidence inadmissible. For example, the appearance of bias or the mere fact that an expert has an interest or connection with the litigation or a party is not sufficient to render the expert’s evidence inadmissible. Likewise, a mere employment relationship between the expert and a party is insufficient to render the expert’s evidence inadmissible. The opposing party must show that it is clear that the expert is unable or unwilling to provide the court with fair, objective and non-partisan evidence. Factors that could be of concern include whether there is a direct financial interest of the expert in the outcome, or whether there is a familial relationship of the expert to a party.

Once passed the threshold test, any remaining concerns about an expert’s independence or impartiality can be taken into account in the second stage cost-benefit of weighing the benefits and risks of the receiving the evidence.

In this case, the expert testified that she understood and was able to comply with her duty to the court and therefore meets the threshold qualification. The Supreme Court found there was the claim that Grant Thornton would incur liability if the shareholders were unsuccessful in the lawsuit was speculative, and there was no basis that the expert was hired to take a position dictated by the shareholders. In short, there was no reason to exclude her evidence as inadmissible.


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