SCC Rules on Intellectual Disabilities and Equality.

• Date: 01 January 2021
• Author: McKay-Panos, Linda

A recent Supreme Court of Canada (SCC) case, R v Slatter, 2020 SCC 36, provided a strong statement about the treatment of evidence provided by witnesses who have intellectual or developmental disabilities.

Thomas Slatter was convicted at trial of sexually assaulting an intellectually disabled 21-year-old woman (J.M.). The defense appealed the decision to the Ontario Court of Appeal (ONCA). They argued, among other issues, that the trial judge erred by: "not properly assessing the reliability of J.M.'s evidence and failing to address the expert evidence of her suggestibility" (para 56).

At the OCNA, the defence counsel argued that, "while the trial judge thoroughly examined J.M.'s credibility, he failed to address his mind to the reliability of her evidence, especially her propensity for suggestibility" (para 57). The defence asserted that the trial judge's reasons were therefore insufficient (para 57).

At trial, the Crown introduced evidence from expert Dr. Jones to prove elements of the two offences for which Mr. Slatter had been charged. However, defence counsel thoroughly cross-examined Dr. Jones on J.M.'s suggestibility (para 61). Further, in his closing submissions, defence counsel repeatedly stressed the importance of this aspect of Dr. Jones' evidence (para 62).

The majority of the ONCA stated (at para 70):

As the Crown correctly submits, a trial judge's findings on the credibility and reliability are entitled to...