"Mopery" is a term often used by Police to refer to a the actions/conduct of a generally worthless individual who really deserves to go to jail, but has not committed any specific act for which he could be arrested. It probably has been tagged onto a booking sheet a few times though. Its an inside joke, not a legal term in any sense.
The average attorney would probably have no idea what you are talking about, a LEO would, at least one who has been around long enough to be eligible for retirement.