R. v. J.-L.J., [2000] 2 S.C.R. 600, 2000 SCC 51, 2000 SCC 51 (2000)

R. v. J.-L.J., [2000] 2 S.C.R.

600

Her Majesty The Queen Appellant v.

J.-L.J. Respondent

Indexed as: R. v. J.-L.J.

Neutral citation: 2000 SCC 51.

File No.: 26830.

1999: December 10; 2000: November 9.

Present: L'Heureux-Dubé, McLachlin, Iacobucci, Major, Bastarache, Binnie and Arbour JJ.

on appeal from the court of appeal for quebec

Criminal law -- Evidence -- Expert evidence - Admissibility -- Mohan criteria - Accused charged with sexual assaults on two young male children -- Expert witness testifying that accused's personality incompatible with any predisposition to commit such offences -- Whether trial judge erred in excluding expert evidence.

The accused was charged with a series of sexual assaults on two young male children. He tendered the evidence of a psychiatrist to establish that in all probability a serious sexual deviant had inflicted the abuse, including anal intercourse, and no such deviant personality traits were disclosed by the accused in various tests including penile plethysmography. After a voir dire, the trial judge excluded the expert evidence because it purported to show only lack of general disposition and was not saved by the "distinctive group" exception recognized in Mohan. The accused was convicted. A majority of the Court of Appeal allowed the accused's appeal and ordered a new trial on the basis that the expert evidence was wrongly excluded.

Held: The appeal should be allowed and the conviction restored.

The trial judge's discharge of his gatekeeper function in the evaluation of the demands of a full and fair trial record, while avoiding distortions of the fact-finding exercise through the introduction of inappropriate expert testimony, deserves a high degree of respect. In this case, the trial judge was not persuaded that the Mohan requirements had been met.

Novel science is subject to "special scrutiny". In this case the psychiatrist was a pioneer in Canada in trying to use the penile plethysmograph, previously recognized as a therapeutic tool, as a forensic tool. Moreover, if expert evidence were accepted that the offence was probably committed by a member of a "distinctive group" from which the accused is excluded, it would be a short step to the conclusion on the ultimate issue of guilt or innocence. This was another reason for special scrutiny.

The "distinctive group" exception sought to be applied here requires that it be shown that the crime could only, or would only, be committed by a person having distinctive personality traits that the accused does not possess. The personality profile of the perpetrator group must identify truly distinctive psychological elements that were in all probability present and operating in the perpetrator at the time of the offence. The Mohan requirement that this profile be "standard" was to ensure that it is not put together on an ad hoc basis for the purpose of a particular case. Beyond that, the issue whether the "profile" is sufficient depends...

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