What does "sharp" mean? It's not just an epistomological, linguistic or abstract question. It matters. Like here.
The defendant here gets convicted of violating Section 4502(a) of Penal Code, which prohibits convicts from possessing a wide variety of things in the joint -- e.g., "a blackjack, slungshot, billy, sandclub,sandbag, or metal knuckles," etc. -- including "any dirk or dagger or sharp instrument." Defendant partially melted down a plastic CD case into something that was rounded but a bit pointy at the end. You could surely use a "pointy" thing as a means of hurting someone. But is it "sharp"?
I think that Justice Sims gets this one exactly right. Maybe the instrument here was sharp, or maybe it wasn't. But the instruction read to the jury here -- in a case in which the "sharpness" of the item was hotly disputed at trial -- merely said that "a sharp instrument is an instrument that can be used to inflict injury and that is not necessary for the inmate to have in his possession." Uh, no. That's not what a "sharp" instrument is. At all. That instruction would (as Justice Sims correctly notes) mean that even a blunt baseball bat was a "sharp instrument" under the statute. Which it ain't.
The error was compounded by the prosecutor, who said the following at closing argument: ""Now, this next [instruction] here is probably the critical definition in the case. A sharp instrument is an instrument that can be used to inflict injury and that is not necessary for the inmate to have in his possession. That tells you that is what a sharp instrument is. Let me just repeat that. A sharp instrument is an instrument that can be used to inflict injury, that's the first part, and that is not necessary for the inmate to have in his possession. That's the central definition in this case. That tells you what a sharp instrument is. If the evidence meets that definition, we've proved that there is a sharp instrument." Which accurately summarizees the instruction, of course. But also proves why we've got to reverse.
Which just goes to show that, sometimes, highlighting why you should win at the trial court level ain't such a great thing once the case goes up on appeal.
"That pointy thing is sharp." "You're looking sharp today." "You're quite a sharp character." Same word. Lots of (uncertain) meanings.
In short, linguistics ain't only for Noam Chomsky. We ordinary folk sometimes have to delve into it as well.