During a civil jury trial arising from a motor vehicle accident, the plaintiffs sought to exclude the testimony of a defence neuropsychologist regarding neuropsychological testing and symptom validity assessment.
The court applied the admissibility framework for expert evidence from R. v. Mohan and the two‑step reliability analysis from R. v. Abbey.
While the expert’s methodology raised concerns regarding cultural and linguistic validity of standardized tests and the absence of normative data for the plaintiff’s background, the court concluded the opinion met the threshold reliability for admissibility.
To preserve fairness and avoid improper commentary on credibility, the court permitted the expert to testify on testing methodology, behavioural observations, and differential diagnosis but prohibited opinions implying deceit, malingering, or general credibility.
The evidence was therefore admitted subject to strict limits and jury instructions.