Even if a trial judge determines that an accused’s statement to the police was voluntarily made, there may still be portions of the statement that are inadmissible and properly subject to editing. The prosecution cannot use a voluntary statement made by the accused to inject inadmissible content into a criminal trial.
One area of concern is when the police ask questions of an accused during an interrogation that would be improper for a Crown to ask during the cross-examination of the accused at trial.
For example, in R. v. L.(L.), 2009 ONCA 413, a unanimous Court of Appeal held that the trial judge should have ordered the excision of the questions and answers during the interrogation that called upon the accused to explain why the complainant would fabricate the allegation. As Justice Simmons elaborates, beginning at para. 14:
Questions in cross-examination that ask an accused person to explain why a complainant would fabricate his or her allegations are improper for two reasons.
First, as a general matter, it is improper to invite one witness to comment on the veracity of another…
Second, questions of this type create a risk of shifting the burden of proof because they may mislead the trier of fact into focusing on whether the accused can provide an explanation for the complainant's allegations instead of focusing on the central issue of whether the Crown has proved beyond a reasonable doubt that the allegations are true….
Contrary to the submissions of the trial Crown, the fact that it may be appropriate for the police to ask such questions as part of an investigation does not mean that portions of an accused's statement in which such questions are asked are properly admissible. This court made that clear in F. (C.). (citations omitted, emphasis added)