Upton Sinclair also referenced a similar argument in his book The Profits of Religion, published in 1917 :

Not merely was my own mail opened, but the mail of all my relatives and friends — people residing in places as far apart as California and Florida. I recall the bland smile of a government official to whom I complained about this matter: “If you have nothing to hide you have nothing to fear.” My answer was that a study of many labor cases had taught me the methods of the agent provocateur. He is quite willing to take real evidence if he can find it; but if not, he has familiarized himself with the affairs of his victim, and can make evidence which will be convincing when exploited by the yellow press.[2]