Commercial Litigation and Dispute Resolution Blog

The Ontario Court of Appeal’s recent decision in R v. Hason^[1] underlines the critical importance of expert evidence not only being reliable and impartial but also appearing to be reliable and impartial. The case is also a reminder to litigators and anyone involved in litigation involving expert evidence that doing due diligence on your expert requires a truly deep dive.

In Hason, the Court of Appeal, of its own initiative, raised the issue of the reliability of an expert’s testimony based on a history of careless practice—namely, using a boilerplate template for the analysis portion of his expert opinion. Although Hason was decided in the criminal context, the Court of Appeal’s reasoning applies to expert evidence in the civil context, and should encourage litigators to not only do their due diligence on the background of experts providing testimony in a case but also to ensure that the expert’s process in arriving at their conclusion or expert opinion is fully understood.

Summary of Decision 

The trial judge in Hason convicted the accused of sexual assault and designated him as a dangerous offender. During sentencing, the trial judge relied heavily on expert testimony from a psychiatrist that had examined the accused, and, in reliance on that expert evidence, imposed an indeterminate prison sentence.^[2]

The accused appealed his conviction, dangerous offender designation, and indeterminate sentence and the appeal was heard in the normal course.  Following the oral hearing, the Court of Appeal, through their own research, became aware of the case of R v Nettleton^[3] – a case which had been decided after the trial judge’s decision in Hason. In Nettleton, the same psychiatrist relied on by the trial judge in Hason, had admitted to a pattern of using a template or boilerplate language (to be copied and pasted from past reports with limited review) for the analysis portion of his dangerous offender reports – the very section on which judges typically rely.^[4]

As a result of uncovering this pattern of using boilerplate analysis, the Court in Nettleton rejected the expert’s testimony as unreliable. Having learned of the Nettleton decision, and to ensure procedural fairness, the Court of Appeal sought written submissions from both Crown and defense on the impact of this new information on the treatment of the psychiatrist’s testimony in Hason.^[5]

Notwithstanding that neither side argued that the findings in Nettleton would have impacted the trial judge’s decision, the Court of Appeal held that, given the psychiatrist’s pattern of inserting boilerplate language for the analysis portion of his expert reports, it could not rely on the psychiatrist’s findings without corroboration. The Court of Appeal ordered a new sentencing hearing with a fresh assessment by a different expert.^[6]

Overview of Admissibility of Expert Evidence

The basic test for the admissibility of expert testimony in Canada was outlined by the Supreme Court of Canada in R v Mohan, and subsequently modified by White Burgess Langille Inman v Abbot and Haliburton Co., and R v Abbey.^[7] At the first stage, the expert’s evidence must meet all four factors of being relevant, necessary in assisting the trier of fact, not barred by any exclusionary rule, and from a properly qualified expert.^[8] At the second stage, the Court plays a gatekeeping role by balancing the probative value of the evidence against its prejudicial effect, considering the legal relevance, necessity, reliability and absence of bias.^[9]

Hason deals with the second, gatekeeping portion of the test. The Court in Nettleton found that the psychiatrist’s presumption that his opinion was accurate, and attempts to minimize errors, even after being confronted with his careless practice, indicated that he was biased, incapable of objectively evaluating problems with his assessment, and raised serious concerns about the reliability of his evidence.^[10] These failings were sufficiently systematic and severe as to call the reliability of his testimony in unrelated proceedings into question.^[11] While the Court of Appeal in Hason raised serious concerns, it did not treat this as a blanket dismissal of this particular expert’s testimony, stating that “depending on all the circumstances, including but not limited to if the defence did not challenge [the expert’s] reliability and/or expose any errors, his opinion was limited in scope, the sentencing judge relied less heavily on it, or other expert evidence confirmed his testimony”, an expert’s demonstrated careless practice would not necessarily undermine the expert’s testimony.^[12]

Key Takeaways

This decision highlights the importance of counsel conducting due diligence on both their own experts and those relied on by opposing counsel. A pattern of careless or sloppy conduct or conduct calling into question the integrity of the expert’s opinion– even from a respected expert with significant experience testifying at trial, as was the case here – may call the reliability and impartiality of their evidence into question.^[13] This case also highlights the importance Courts will place on their gatekeeping role, given the power of expert testimony and the serious possibility of biased or unreliable expert testimony leading to a miscarriage of justice.^[14]

^{[1] R v Hason, 2024 ONCA 369 [Hason].}

^{[2] Ibid at para 31.}

^{[3] R v Nettleton, 2023 ONSC 3390 [Nettleton]}

^{[4] Ibid at para 87.}

^{[5] Ibid at paras 97-98.}

^{[6] Ibid at paras 121-123.}

^{[7] R v Mohan (1994) 2 SCR 9 [Mohan]; White Burgess Langille Inman v Abbot and Haliburton Co. 2015 SCC 23; R v Abbey, 2017 ONCA 640 [Abbey].}

^{[8] Mohan ibid at page 20.}

^{[9] Abbey supra note 8 at para 48.}

^{[10] Hason supra note 1 at para 93.}

^{[11] Ibid at para 94.}

^{[12] Ibid at para 127.}

^{[13] Ibid at para 30.}

^{[14] Ibid at para 1.}