is a leading

Supreme Court of Canada The Supreme Court of Canada (SCC; french: Cour suprême du Canada, CSC) is the Supreme court, highest court in the Court system of Canada, judicial system of Canada. It comprises List of Justices of the Supreme Court of Canada, nine justices, wh ...

decision on the use of

expert witness An expert witness, particularly in common law countries such as the United Kingdom, Australia, and the United States, is a person whose opinion by virtue of education, training, certification, skills or experience, is accepted by the judge as ...

es in trial testimony.

Background

Chikmaglur Mohan was a pediatrician in

North Bay, Ontario North Bay is a city in Northeastern Ontario, Canada. It is the seat of Nipissing District, and takes its name from its position on the shore of Lake Nipissing. North Bay developed as a railroad centre, and its airport was an important military ...

. He was charged with

sexual assault Sexual assault is an act in which one intentionally sexually touches another person without that person's consent, or coerces or physically forces a person to engage in a sexual act against their will. It is a form of sexual violence, which ...

of four teenage patients. During his trial, the defence tried to put Dr. Hill, a psychiatrist, on the stand as an expert on sexual assault. Hill intended to testify that the perpetrator of the offence must have possessed several abnormal characteristics, which Mohan did not have. In a

voir dire (; often ; from an Anglo-Norman phrase meaning "to speak the truth") is a legal phrase for a variety of procedures connected with jury trial A jury trial, or trial by jury, is a Trial, legal proceeding in which a jury makes a decision or Qu ...

hearing, Hill testified that the culprit in the first three assaults was likely a pedophile, while the fourth assault would have been by a sexual psychopath. This evidence was held to be inadmissible by the judge. Mohan was eventually convicted at trial but his conviction was overturned on appeal. The issue before the Supreme Court was whether Hill's testimony could be admitted as that of an expert witness, and whether the testimony would violate the rule against

character evidence Character evidence is a term used in the law of evidence to describe any testimony or document submitted for the purpose of proving that a person acted in a particular way on a particular occasion based on the character or disposition of that per ...

Opinion of the Court

Justice Sopinka, for a unanimous Court, allowed the appeal and held that the evidence should be excluded. Expert evidence, stated Sopinka in the ruling, should be admitted based on four criteria: * It must be relevant, * it must be needed to assist the trier of fact, * it should not trigger any exclusionary rules, and * it must be given by a properly qualified expert. Relevance is a question of law and so is determined by the judge. Where it approaches the "ultimate issue" of the trial, the standard for inclusion must be stricter. To be considered necessary, the expert evidence must be outside the likely everyday experience of a judge and jury. In that regard, Sopinka stated: In total, the expert evidence should be included where the probative value of the evidence outweighs any prejudicial effect it may cause. In the current case, Sopinka found that there was insufficient evidence to suggest that there was any clear standard for determining the profile of a pedophile or psychopath. Thus, the expert evidence was not considered reliable. Furthermore, the expert's evidence was not sufficiently relevant to be of any help.

Impact

The criteria set out in ''Mohan'' did not include a stand-alone requirement for experts to have independence and impartiality, but many of the lower courts have attempted to infer such a requirement. In 2013, the

Nova Scotia Court of Appeal The Court of Appeal for Nova Scotia (Nova Scotia Court of Appeal or NSCA) is the highest appeal court in the province of Nova Scotia, Canada. There are currently 8 judicial seats including one assigned to the Chief Justice of Nova Scotia. At any gi ...

held that that is not required. In affirming that ruling in 2015, the

disagreed with the Nova Scotia Court of Appeal and held that the expert's duty to the court creates a threshold requirement for the admissibility of the expert's evidence, in which the determining factor is "whether the expert’s opinion would not change regardless of which party retained him or her".

References

External links

* Canadian evidence case law Supreme Court of Canada cases 1994 in Canadian case law {{canada-law-stub