Rape by mistake?

Via the Volokh Conspiracy

Here's a story for married guys who miss the excitement of single life. A guy in Sydney picks up a woman at a party and goes back to her apartment. They get into bed. He gets up to use the head. He is (surprise) drunk and comes back to the wrong bedroom. He accidentally gets into bed with his intended conquest's flatmate who is asleep. It's dark and he claims not to notice the difference between this woman and the one who brought him home (with whom, I think it is safe to say, he was not overly familar.) He initiates the old horizontal macarena.

But ... she doesn't notice he is a stranger, either. It is dark, remember, and she thinks that this is her boyfriend, who had apparently been asleep on the couch. She, should we say, reciprocates - presumably with gusto.

When the lights go on, she is horrified and hysterical. She claims (and I believe her) that she was "quite gutted" that it was not her boyfriend. Our back door man is surprised and gets pushed out the front door just before the boyfriend wakes up. Boyfriend wants to beat the guy up, if not to protect her honor, at least as punishment for demonstrating that, in some areas of the boyfriend department, he must be a bit nondescript.

Our "victim of the night" is not about to take the "sorry, wrong body" excuse.

He is charged with sexual assault. He plans to plead not guilty.

Fascinating questions.

Is mutual mistake a defense to sexual assault?

Or let's assume he realized he was in the wrong room, is he guilty of misrepresentation? Would that vitiate her consent? Did he have an obligation to say "You don't know me, but how about ..."? What if she mentioned Boyfriend's name during amor? Should men think it strange if a woman speaks another's name in passion? Might that not be a fairly regular occurence for some guys?