You have to convince a sheriff to deputize you first. For some reason this is easier for celebrities. Go figure. What does that say about the judgement of the sheriff that approve that sort of thing? Not sure what a sheriff's responsibilities are in the US system, but if that's the same person responsible for deciding that a SWAT team is necessary to investigate a poker game going on in someone's house, it's not surprising to see poor decisions being made in that area too.