And no doubt one can weaken a glass jar with a knife. But nothing is more common or, we should have thought, more harmless than to use a knife or a razor blade to remove a label from a jar or bottle. People do this all the time with the price labels on bottles of wine. It was there, obviously, with K-Mart's permission. If one just wants to efface a label one can usually do that by scraping it off with a fingernail, but to remove the label intact requires the use of a knife or a razor blade.
Invited misuse is no de- fense to a products liability claim.
Invited misuse is not misuse. As to them, the defense of misuse must fail, at this stage of the proceedings, for two other reasons. The evidence does not establish with the certitude required for summary judgment that the use of an Exacto knife to remove a label from a jar is a mis- use of the jar. And in a regime of comparative negligence misuse is not a defense to liability but merely reduces the plaintiff's damages, unless the misuse is the sole cause of the accident. Even so, the defendants point out, it is always possible that the jar was damaged while it was sitting unattended on the top of the refrigerator, in which event they are not responsible.