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In a majority decision written by Chief Justice McLachlin, the Supreme Court of Canada has ruled that people with ‘mental’ or intellectual disabilities can testify in criminal cases on a promise to tell the truth, just like any other Canadian. The D.A.I. case involved a woman with intellectual disabilities who was denied the opportunity to give evidence in a case in which her stepfather was charged with sexual assault. The ruling acknowledges the evils of sexual assault, and the vulnerability to assault that people with mental disabilities face. The Court makes it clear that in the original trial the lower court erred in its interpretation that section 16 of the Canada Evidence Act requires a person to demonstrate an understanding of the meaning of a promise to tell the truth. The Supreme Court states that a correct reading of section 16 is that a witness can testify if she can communicate the evidence and can promise to tell the truth, and that the additional barrier of requiring a witness to explain in abstract terms the meaning of promise, truth or lies should not be part of the test of witness competency. The Court also affirms the duty to accommodate the witness in the types and ways of questioning, that the primary source of evidence for the witness's competence should be the witness herself, that those who are most familiar with the witness and her everyday situation should be relied on for evidence of her development and that if an expert is needed, preference should always be given to experts who have personal and regular contact with the witness.
CACL was originally granted intervenor status in this case, and worked with other intervenors in preparing the arguments.
The full text of the ruling can be found on the Supreme Court Judgments website
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