“If you have nothing to hide, you have nothing to fear” (or, “You have nothing to fear if you have nothing to hide”) is a statement frequently given by someone who wants to search someone else (over that person’s privacy objections). However, it doesn’t necessarily follow that someone who wants to keep certain matters private has anything embarrassing to hide. For example, a public official might want to keep family matters private, but this doesn’t necessarily imply that there is anything improper.

American author Upton Sinclair 1878-1968) wrote in The Profits of Religion: An Essay in Economic Interpretation (1918):
 
“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 provacateur. 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.”
 
United States Solicitor General Francis Biddle (1886-1968) said in 1940 about a U.S. drive to list and fingerprint aliens that “if you have nothing to hide, you have nothing to fear.” Syndicated newspaper columnist Carl Rowan (1925-2000) wrote in 1971 that “people who have nothing to hide have nothing to fear” was an old argument because “it is safe to say that every member of the Supreme Court would be in for serious trouble and embarrassment if we had secret recordings of all their utterances, business dealings and the like.”
 
The saying has become extremely popular in the Internet information age. An article by Toby Stevens in Computer Weekly on February 25, 2009, “Debunking a myth: If you have nothing to hide, you have nothing to fear,” gave the term “Nothing to hide, nothing to fear” (NTHNTF) an acronym.
     
 
Hathi Trust Digital Library
Google Books
The Profits of Religion:
An Essay in Economic Interpretation
By Upton Sinclair
Pasadena, CA:  Published by the author
1918
Pg. 145:
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 (Pg. 146—ed.) agent provacateur. 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.
 
Google News Archive
25 August 1940, Windsor (Ontario) Daily Star, “Alien Check On Tuesday; U.S. Opens Drive to List and Fingerprint 3,600,000,” pg. 13, col. 2:
Solicitor General Biddle assured aliens in a broadcast last night that “if you have nothing to hide, you have nothing to fear.”
 
Google News Archive
31 January 1955, Portsmouth (OH) Times, “Radio And Television: Note On Propaganda” by John Crosby, pg. 28, col. 2:
I think the best propaganda in the world is simply to be yourself. If you have nothing to hide, you have nothing to fear.
 
13 April 1971, Seattle (WA) Times, “Open season for electronic fishing” by Carl T. Rowan, pg. 12, col. 6:
SURE, THE SELF-RIGHTEOUS and sanctimonious will haul out the old argument that “people who have nothing to hide have nothing to fear.” But it is safe to say that every member of the Supreme Court would be in for serious trouble and embarrassment if we had secret recordings of all their utterances, business dealings and the like.
 
OCLC WorldCat record
If you have nothing to hide, you have nothing to fear? : an examination of the 1997 Security Intelligence Service Amendment Bill and protest directed against it : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts at Massey University
Author: Peter Ridge
Dissertation: Thesis (M.A.)—Massey University, Palmerston North, 2004.
Edition/Format: Thesis/dissertation : Thesis/dissertation : Manuscript Archival Material : English
 
OCLC WorldCat record
Nothing to Hide, Nothing to Fear? Legislation to introduce National ID Cards may be imminent
Author: S Chakrabarti; C Gallagher
Edition/Format: Article : English
Publication: COUNSEL, no. May, (2004): 10-13
Database: British Library Serials
 
Harry Potter Wiki
“As your new Minister for Magic, I promise to restore this temple of tolerance to its former glory. Therefore, beginning today, each employee will submit themselves… for evaluation. But know this: you have nothing to fear if you have nothing to hide.” —Pius Thicknesse at the Ministry of Magic.[src]
(From Harry Potter and the Deathly Hallows, the seventh and final of the Harry Potter novels written by British author J. K. Rowling, published in 2007—ed.)
   
Google Books
Surveillance: Power, Problems, and Politics
Edited by Sean Patrick Hier and Joshua Greenberg
Vancouver, BC: UBCPress
2009
Pg. 100:
We are all familiar with the common perception that if you have nothing to hide you have nothing to fear, but for many individuals and groups the experience of being watched is not innocuous; some of us have good reason to worry aboutthe gaze of others.
 
Computer Weekly
Debunking a myth: If you have nothing to hide, you have nothing to fear
By Toby Stevens on February 25, 2009 9:07 PM
The idea that an individual can live in a surveillance society with nothing to fear so long as they have nothing to hide may, on the face of it, appear attractive. For those of us who think of ourselves as ‘honest’ - we pay our taxes, don’t commit murders and are loyal to our partners - why indeed should we fear surveillance?
 
“Nothing to hide, nothing to fear” (NTHNTF) is a myth that is built on certain false assumptions, and these assumptions are never questioned when it is wheeled out as an argument to support whatever draconian surveillance measure is being pushed out in the face of citizen opposition (commercial organisations rarely try such an approach, since it dooms them to failure from the very beginning).
   
New York (NY) Times
The Certainty of Doubt
By CULLEN MURPHY
Published: February 11, 2012
(...)
Visitors to Britain for this summer’s Olympics will notice the CCTV cameras — there are reportedly more than four million of them — that monitor ordinary daily activity throughout the country. This effort, the most advanced in the world, is supported by the slogan “If You Have Nothing to Hide, You Have Nothing to Fear.”
 
Zero Hedge
STaSi USA…
Submitted by williambanzai7 on 06/11/2013 14:06 -0400
“YOU HAVE NOTHING TO FEAR,
IF YOU HAVE NOTHING TO HIDE.”
Joseph Goebbels, 1933