Check this one out. A guy in New Mexico pretending to be a police officer pulled over an actual police officer. As you can probably imagine, that did not end well. Of course, the man in question says he did no such thing. Mr Tyree Appleberry says he did not claim he was a police officer, did not imply he was one, and was not arrested for impersonating a cop. All he did was follow a guy and then turn the strobe lights of his truck on. Then when the guy pulled over, he got out and asked for ID. Nah, that doesn’t sound anything at all like what a cop does.
Mr Appleberry was given a misdemeanor citation (basically a fine) for impersonating an officer and arrested on an outstanding warrant. So technically, Mr Appleberry was not arrested for impersonating a cop–but impersonating a cop is sure what got him arrested.