In a 2021, the Alberta Court of Appeal, in R. v. Bernier, 2021 ABCA 27, ordered a new trial on a sex assault conviction. The appeal was successful due to the trial judge wrongfully relying on evidence taken from the police interview of the accused, to the effect that the complainant had fabricated a conspiracy against him. This was offside the rule that a witness cannot be called upon to impeach the evidence of other witnesses in a trial.
It was alleged at trial that Bernier attended a house party at around 1 am, where after he engaged in consensual sex with another witness, MD. Afterwards he entered the bedroom of the complainant at around 3 am and performed oral sex and then had vaginal sex with the complainant. The complainant testified that she had consumed alcohol and marijuana that evening and was sleeping at the time of the assault in the bedroom next to MD’s. She woke up to find Bernier with his head between her legs, and that afterward Bernier commenced vaginal intercourse with the complainant. During the police interview Bernier indicated that the complainant was an enthusiastic participant in the sex that had occurred. The police then asked the complainant:
… The first thing you’ve got to ask yourself is why would [the complainant] lie? I mean why would [the complainant] lie? That is the absolute first thing I look at is what’s the motive here for her lying because, as traumatic as this is for you, this is also a traumatic process for her.
Why would she lie? That’s the first thing I ask. … This is why I’m saying that it’s important that I hear from you is why would she lie. Like give me a reason why she would lie? Why do you think she would lie?
Bernier’s response was, in essence, that the complainant and MD conspired to lie to the police because they were friends and they were mad that Bernier had sex the complainant after he had sex with MD. Bernier did not testify at trial and the defence argued at trial that the complainant had suffered a “blackout”, and was unable to recall consenting to the sexual acts with Bernier.
The trial judge found Bernier guilty at paragraphs 147-149 of the decision:
 I find that Mr. Bernier entered the spare bedroom and found C asleep. He then engaged in sexual activity with her, starting while she was asleep, including intercourse, and then concluding after she had awakened.
 I find that C did not and could not have effectively given consent while she was sleeping and more latterly while the oral sex transitioned to intercourse, she was not asked for nor gave her consent.
 I conclude that the Crown has proven all elements of the offence of sexual assault beyond a reasonable doubt.
The Court of Appeal found no issue with the trial judge’s approach to the W.D. analysis (a complicated credibility assessment, which is beyond the scope of this post). However, the Court of Appeal took issue with the following two reasons provided by the trial judge for the conviction:
 Finally, I have two other reasons for rejecting Mr. Bernier’s evidence.
 First, he alleged in the interview with Detective Levesque that the inhabitants in the house engaged in a conspiracy to frame him for sexual assault. The reason he gave for this conspiracy is that he had sex with both [MD] and C on the same night. There is nothing before me to suggest that this has engendered animus in the witnesses against Mr. Bernier. [MD] and
[TC] expressed no animus. From her presentation, I can surmise that and understand why C was
not happy about the sexual contact with Sebastian, but her credibility was not questioned.
 Thus, a vindictive and elaborate plot to frame Mr. Bernier, predicated on revenge and involving three and perhaps up to five individuals (at least two of whom profess to be friends of Mr. Bernier), strikes me as a rather implausible explanation for this prosecution. This rationalization for his predicament casts a shadow of implausibility over the totality of what he said.
Focusing on these portions of the trial judge’s reasoning, the Court of Appeal reiterated the principle that an accused person cannot be called upon to explain or theorize as to why a complainant would make an allegation against him. The Court of Appeal further noted that Crown cannot cross-examine an accused on the veracity of Crown’s own witnesses, or invite comments from the accused about the witness’s motive to lie. This general principle was noted as going at least as far back as 1935 in the Supreme Court of Canada’s decisions in Markadonis v. The King, and has been adopted in at least 10 decisions from Courts of Appeal across Canada. The key rationale behind this rule, that it is impermissible to ask accused “why would some one lie about what you did?”, is that it undermines the presumption of innocence by shifting the onus of proof to the
accused. Seeking the accused to provide and explanation for why a complainant would make a false allegation is wrong because the judge can then find accused to be not credible on the ground that he could not provide a good explanation. This is what happened in this case.
The accused did not testify at trial, and those questions were not put to him by the Crown. However, the police statement, where such questions were put to the accused, were admitted into evidence at trial. The Court of Appeal relied on the decision in R. v. LL (2009 ONCA 413) the Ontario Court of Appeal stated that portions of a videotaped statement in which police asked the accused why the complainant would make the allegations, should not have been put to the jury. The reasons for not admitting into evidence such questions of the accused are two-fold: 1.) it is improper to invite one witness to comment on the veracity of the other, and 2.) asking such questions shifts the burden of proof to the accused.
The Court of Appeal in this case further commented that in additional to the police questioning of Bernier being highly prejudicial, the trial judge clearly relied on the questions asked and answers given – that Mr. Bernier believed that others at the party conspired against him to cook up this allegation because he had sex with two women in the group. Essentially the trial judge allowed the Crown to make the accused speculate about what’s going on in the complainant’s head and then
used accused’s speculation against him saying in assessing his overall credibility (truthfulness).
The Court of Appeal returned the case to the Court of Queen’s Bench for a new trial, noting that “Unfortunately, this is paradigmatic case for why the rule continues, over the decades, to have such force.”