You're right. Even though it's negating the mental element, we treat it like a defence. The crown would put in their case. The defence, in order to have that defence left with the jury, would have to give an air of reality to the defence, which means they would have to point to some evidence on the record that's capable of raising a reasonable doubt on the issue of the accused's belief. That evidence could come from the crown's own case if the complainant's evidence on cross-examination indicates that there was some misunderstanding or some potential for misunderstanding. I suppose it would be enough simply based on the crown's own evidence, so it's not necessary that the accused testify in order to raise the defence. Practically, as a tactical matter, it often takes the form of the accused testifying and giving a different version of events.
The reason the defence is so rare is that, generally speaking, when the accused does testify, the accused testifies to a version of events that are wholly different and involve enthusiastic and voluntary consent. Generally speaking, courts say that if the complainant's version is, “I absolutely did not consent, and that was clear to anybody and there was no mistaking it,” and the accused's version of events is, “She was a willing and enthusiastic participant and has only made this up after the fact,” there's really not much room for a third version of events, some kind of middle ground.
That mere fact, regardless of what we're putting into the Criminal Code, means that the defence is not one that should be arising very often. It would have to be an unusual set of facts where there is some version of the evidence in which we could imagine that the complainant did not want the sexual touching to take place, but the accused believed that he had a “yes” from the complainant. That's true regardless of these amendments or anything else.
The threshold is not huge at the initial stage. It's the air of reality threshold. Is there evidence which, if believed, is capable of raising a reasonable doubt? Of course, there's the question of the accused's belief in the circumstances known to him at the time. Did he believe he had a “yes” by words or by conduct, and is there some evidence that the accused took reasonable steps in those circumstances to ascertain the presence of consent? That's an important part of the defence as well that's been part of the law since the 1992 reforms.