Boy and girl have sex. While girl is on top, girl shifts her body in a way that causes a painful injury to boy. (Really, I hear this sort of injury is indeed extremely painful and debilitating.)
Boy then sues girl, for negligence. Hey, boy's lawyer doubtless argued (I'm guessing on this, though everything else is true): If girl had hit boy with her car, or had fallen on boy from a ladder, she would have been liable if a jury found that she hadn't exercise reasonable care. Why not here?
A Massachusetts appellate court just yesterday told boy to take a hike. Interestingly enough, his legal claim was far from outlandish: The general rule is that people who injure others can be held liable if they were acting negligently (i.e., didn't exercise the care that a reasonable person would have exercised under the circumstances). Still, the court got it right -- do we really want trials about how exactly the Reasonable Sexual Partner would have had Reasonable Sex?
I love the law; never a dull moment. How long, by the way, until this plot makes it onto one of the law TV shows? Or has it already, and I've missed it?