You’ve seen it many times times in your travels around the World Wide Web: error 404, file not found. This is but one of many HTTP errors.

There’s a new one that I hope we don’t see very often but it’s a win for transparency. I’m talking about error 451: Unavailable For Legal Reasons1. The idea was hatched when ISPs in the UK were ordered to block the Pirate Bay website in 20122. When users attempted to visit the site, their ISP offered up error 403: forbidden. This seems appropriate, but the reasons for the restriction are not a part of the error. Also, a 403 is typically the result of a lack of privileges, resulting in the server denying the request. In the case of a government ordered block, the client request never makes it to the server.

Granted many oppressive governments will never allow the 451 error because they don’t want the transparency it provides. Still, even the possibility of having censorship be labeled as such, and not as a technical problem, is a win.

And in case you recognize the error number itself, it was indeed taken from the title of Ray Bradbury’s 1953 novel Fahrenheit 451. The novel presents a future American society where books are outlawed and “firemen” burn any that are found.3


  1. Tim Bray, “An HTTP Status Code to Report Legal Obstacles,” IETF Datatracker, November 10, 2015.
  2. Michael Byrne, “The HTTP 451 Error Code for Censorship Is Now an Internet Standard,” Motherboard, December 21, 2015.
  3. Fahrenheit 451,” Wikipedia, retrieved December 21, 2015.