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EVIDENCE - Opinion evidence - Expert evidence - Basis for opinion

Thursday, September 17, 2020 @ 6:09 AM  


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Appeal by the accused from conviction for aggravated sexual assault. The appellant had vaginal intercourse with three women, knowing he was HIV positive, during a time when his viral load was not low. He failed to disclose his HIV status. Although he wore a condom each time, he was not on antiretroviral medication. The complainants testified that they would not have consented to having sexual intercourse with the appellant had they been aware of his HIV-positive status. The appellant argued the Mabior test should be changed to reflect the fact that condom use alone was sufficient to negate the realistic possibility of transmission. He argued the Mabior requirement that condom use be coupled with a low viral load to negate a realistic possibility of transmission of HIV was excessive. The appellant’s application to reopen trial to introduce expert evidence from the same expert who testified in Mabior that use of a condom alone negated any realistic possibility of transmission was dismissed. The appellant now sought to introduce the same expert evidence on appeal. The expert had changed his mind since Mabior about the appropriateness of using population-level statistics when considering the risk of HIV transmission in the context of the criminal law. He now opined that it was incorrect to state that in any individual case condoms were only 80 per cent to 85 per cent effective because, in his current view, correct and consistent condom use led to 100 per cent protection from transmission when considered on a per act basis where nothing went wrong. The appellant argued this new evidence now verified empirically that consistent and correct condom use brought the risk of HIV transmission to zero and Mabior should be adapted accordingly.

HELD: Appeal dismissed. The fresh evidence on appeal was not cogent and was not admissible. When considered against all the evidence at trial, the new evidence was not sufficiently probative to allow this court to change the Mabior rule, so that condom use alone could negate the realistic possibility of HIV transmission, thereby requiring acquittals to be entered. The appellant’s argument in favour of a condom alone rule rested on a challenge not to the factual pillars upon which Mabior rests, but to the legal foundation upon which the decision rested. The appellant’s position conflated consistent and correct condom use with the ideal scenario in which condoms functioned perfectly, thereby failing to account for real-world situations in which condoms did not function perfectly. His position was contrary to the principles underlying epidemiology and the criminal law and with the Charter values animating the Mabior rule. The use of population-level statistics to assist in determining the risk of HIV transmission during condom-use-alone sexual intercourse was entirely consistent with our modern notion of consent to sexual activity and what could operate to vitiate that consent. Cumulative risk over many sex acts, and differing baseline risks depending upon the nature of the sex acts, indicated the wisdom of the Mabior approach in creating a singular, easy-to-understand, and easy-to-apply rule for the application of the criminal law. There was nothing in the new evidence that revealed a change in the facts upon which Mabior’s legal reasoning rested.

R. v. N.G., [2020] O.J. No. 3313, Ontario Court of Appeal, P.D. Lauwers, G.T. Trotter and J.M. Fairburn JJ.A., August 5, 2020. Digest No. TLD-September142020008