At trial, the defendant was found vicariously liable for sexual abuse alleged to have been committed against the plaintiff by its former employee. The defendant appealed on the basis that the trial judge erred in admitting the opinion evidence of a mental health clinician who gave evidence at trial as a participant expert. The court held that the plaintiff’s treating doctor, who had not delivered a Rule 53 expert report, ought not to have been permitted to provide opinion evidence as to whether the alleged sexual assaults occurred (liability) and whether the plaintiff suffered harm caused by such assaults (damages). Furthermore, the treating doctor’s expert opinions going to the issues of liability and causation failed to satisfy the threshold requirements for admissibility under the first step of the test in R v. Mohan and ought to have been excluded under the second step of the admissibility test because the prejudicial effect of the evidence outweighed its probative value. The appeal was allowed and a new trial ordered.
