Bagpiper wins case about sock dagger

A year and a half ago, bagpiper Jeff McCarthy was fined for wearing the traditional sgian-dubh, the small dagger that’s part of a full Highland outfit. The charges have been dropped and he’s getting his knife back.

In the previous version of the blog (which I can’t access at the moment) I believe we had a discussion about the legalities of carrying a knife, but I don’t remember the details. I almost always have some kind of knife with me simply because it’s useful in so many ways. (I also carry a spork and a pair of portable chopsticks.) Leaving aside air travel, surely it can’t be illegal to have a folding knife with you? Anyone have the letter of the law on this?