A proposal has been made for new HTTP error code, to be returned when a page being requested is unavailable because of censorship.
The proposal, which has been submitted to the Internet Engineering Task Force come from Tim Bray, who co-edited the XML and XML namespace specifications and is a Developer Advocate at Google. It specifies a status code new HTTP error code to be returned when a page being requested is unavailable for legal reasons.
Bray exlains that the use of this code:
allows server operators to operate with greater transparency in circumstances where issues of law or public policy affect their operation. This transparency may be beneficial both to these operators and to end users.
He also advises that responses using the 451 status code should include an explanation for the restriction with details of the authority denying access giving this example:
(click inside code snippet to enlarge)
A specific error code to flag page unavailability for legal restrictions is undoubtedly a good idea given the increasing incidence of Internet censorship. Bray acknowledges Ray Bradbury, author of Fahrenheit 451, for his choice of the error code to be displayed, and this seems entirely appropriate.