Vetrovec caution

R. v. Roks, 2011 ONCA 526 contains a helpful review of the need for corroboration (in a loose sense) in a Vetrovec context:

[62]    The principal complaint in this case has to do with the essential characteristics of confirmatory evidence and the capacity of the testimony of one witness, whose evidence is subject to a Vetrovec caution, to confirm the testimony of another witness, whose evidence is subject to the same caution.

[63]    Among the essential elements of a Vetrovec caution is an instruction about the essential characteristics of confirmatory evidence. Jurors are to be told that, in determining the veracity of the suspect evidence, they should look for evidence from another source tending to show that the untrustworthy witness is telling the truth about the guilt of the accused:Khela, at para. 37; R. v. Kehler, [2004] 1 S.C.R. 328, at paras. 17-19; R. v. Sauvé (2004), 182 C.C.C. (3d) 321 (Ont. C.A.), at para. 82, leave to appeal refused, [2005] 1 S.C.R. xv. The trier of fact is to look for confirmation from some other source (the independence requirement) that the suspect witness is telling the truth in some part of his story that goes to show that the accused committed the offence charged (the implicative quality or materiality requirement): Kehler, at para. 19; R. v. Vetrovec, [1982] 1 S.C.R. 811, at p. 829.

[64]    The independence requirement insists that to be confirmatory, evidence must not be “tainted” by connection to the Vetrovec witness: Khela, at para. 39.

[65]    To satisfy the materiality requirement, confirmatory evidence need not implicate the accused: Khela, at paras. 40-41; Kehler, at para. 16. The materiality requirement is met where the confirmatory evidence, in the context of the case as a whole, gives comfort to the trier of fact that the Vetrovec witness can be trusted in his or her assertion that the accused is the person who committed the offence: Khela, at para. 42; Vetrovec, at p. 833.  Where the only issue in dispute is whether the accused committed the offence, to be confirmatory, evidence must comfort the trier of fact that the Vetrovec witness is telling the truth in that regard before convicting on the basis of the Vetrovec witness’ evidence: Khela, at para. 43.

[66]    It is worth reminder that a trier of fact is entitled to convict on the evidence of a Vetrovec witness in the absence of confirmatory evidence where the trier of fact, cautioned about the danger of doing so, is satisfied that the witness is telling the truth: Khela, at para. 37; Kehler, at para. 22; Sauvé, at para. 82.

[67]    Despite the bar against mutual corroboration by those who were participes criminis under the former accomplice rule, there may not be a similar injunction against mutual confirmation by Vetrovec witnesses, at least in the absence of a finding of collaboration or collusion among them: R. v. Winmill (1999), 131 C.C.C. (3d) 380 (Ont. C.A.), at para. 120;R. v. Pollock (2004), 187 C.C.C. (3d) 213 (Ont. C.A.), at para. 161; R. v. Naicker (2007), 229 C.C.C. (3d) 187 (B.C. C.A.), at para. 34; R. v. Illes (2007), 217 C.C.C. (3d) 529 (B.C. C.A.), at paras. 30-31, reversed on other grounds, [2008] 3 S.C.R. 134.