The Watermelon argument is both clever and amusing. But it also only considers one perspective. So frequency doesn't work? Fair enough, but that is not all the data we are capable of gathering. And, when you are going to punish someone in a court of law for something, it needs to be a crime. It seems to me that whether or not the defendant is guilty of a crime is the real argument his lawyer is making. If everyone is doing it, then it is unjust to prosecute just one person and call it a day. Calling an everyday activity in a community a crime allows prosecutors to choose whomever they like from the populace and incriminate them. If the practice is that wide spread, then alternate steps need to be taken to remove it from the community as a whole. The ability to choose anyone from a majority of the populace and convict them of a crime is, unsettling. It is also a big part of what the constitution is geared towards preventing.