Someone in the UK was prosecuted for this; the statute is something like "don't use other peoples' computers in a way they did not intend", and the guy appended

Someone in the UK was prosecuted for this; the statute is something like "don't use other peoples' computers in a way they did not intend", and the guy appended "/../" to the URL to try and read the parent directory listing (it worked). He also lied to police about having done it, but the server logs showed that he had.