In Michael Connelly's novel Trunk Music, Detective Harry Bosch is in trouble with Internal Affairs (again!) and he is interrogated by a particularly righteous IAD officer, John Chastain, who tells him "I take pride in what I do because I represent the public, and if there is no one to police the police then there is no one to keep the abuse of their wide powers in check," and Harry replies to this with a hall of mirrors type question: "But let me ask you this, Chastain . . . who polices the police who police the police?"