I found the following interesting because of my interest in Animal Law, and because it shows that the waivers we sign when we participate in activities really matter! I have been asked to sign a liability waiver when participating in horseback riding and rafting, among other things.
I have read the actual decision in this case, and quite frankly, if there was ever a justification for invalidating a waiver, they would have found it in this case. There was some pretty obvious negligence on the part of the facility owner; a previous history of attacks; and some statements that could have been construed as misrepresentations to the victim. Nevertheless, the court upheld the waiver.