Lou the Cop is one of Wiggum's two frequently used police officers. Lou definitely seems to be the hardest working and most competent of the cops.
Chief Wiggum: Hold it right there, Switches of Eastwick.
Lou: Switches of Eastwick?
Chief Wiggum: I don't want to censor myself. That's how creativity dies.
Chief Wiggum: Who are you, the rules police?
Lou: No, we are the police police.