New ISP HTTP Error Code 451 Proposed for Legal Website Censorship

In the future any website or webpage that is blocked by an ISP, such as following a court order or in response to an adult content filter, could return the HTTP Error Code 451 (“Unavailable For Legal Reasons“), which would include more information about why the content was censored than is currently available.

At present many broadband ISPs that block websites via their internet filtering systems, such as with the recent Newbin and Pirate Bay blocks imposed by the UK’s largest six broadband providers (here), simply return a 403 error code (“Forbidden“) or the more common 404 (“Page Not Found“); though most do add a short explanatory message.

The newly proposed 451 error, which is inspired by the author Ray Bradbury and his 1953 dystopian novel Fahrenheit 451, is the work of Google developer Tim Bray and would still require approval by the Internet Engineering Task Force (IETF) before it could be used.

Introduction to Bray’s Proposal

This document specifies an additional Hypertext Transfer Protocol (HTTP) status code for use when resource access is denied for legal reasons. This 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.

451 Unavailable For Legal Reasons

This status code indicates that the server is subject to legal restrictions which prevent it servicing the request. Since such restrictions typically apply to all operators in a legal jurisdiction, the server in question may or may not be an origin server. The restrictions typically most directly affect the operations of ISPs and search engines.

Responses using this status code SHOULD include an explanation, in the response body, of the details of the legal restriction; which legal authority is imposing it, and what class of resources it applies to.

The IETF is set to meet at the end of July 2012 to discuss the draft and it’s possible that there might be some technical, as well as political, difficulties that would need to be overcome. One issue could occur if the same code is used when blocking technically legal content via an optional service (e.g. adult content filter), in which case we’d like to see consumers being directed to information about how to disable the restriction via the connection owners account.

Draft HTTP Error Code 451 Proposal
http://tools.ietf.org/html/draft-tbray-http-legally-restricted-status-00