This Canadian case (h/t Bashman) involves unmarried partners (who were raising two kids together as well), but the issue isn't limited by their being unwed.
The Court of Appeal majority reasoned that an individual who consents to being sexually manipulated once unconscious has exercised “personal autonomy.” The majority noted that the possibility of withdrawing consent does not exist once one slips into unconsciousness: “The only state of mind ever experienced by the person is that of consent.”On the dissent's theory, one's wife simply cannot, as a matter of law, say "I want you to have sex with me while I'm asleep" -- or rather, that doesn't amount to consent. I appreciate the practical problems raised by feminist critics of the Canadian court's decision, but that just doesn't sound like it can be the right answer.
Writing in dissent, Mr. Justice Harry Laforme countered that the complainant's consent was negated the moment that she passed out.
“Consent ends when the active, independent, operating will ceases,” he said.