451: Web censorship status code

Everyone knows a 404 Web status messages means you can reach the Web server, but it can't find the page you're looking for. In these days of Internet censorship, a new HTTP Web status message, 451, has been proposed for pages and sites blocked by censorship.
Written by Steven Vaughan-Nichols, Senior Contributing Editor

TIm Bray thinks you should know when censorship is blocking your from a Web site.

TIm Bray thinks you should know when censorship is blocking you from a Web site.

Back in the early days of the Web, we set up Hypertext Transfer Protocol (HTTP) status messages to let people know what was going on with a Web server. Today, we still use 401 error messages for pages you're not authorized to see, 403 pages for pages you can't see even with authentication, and the ever popular 404 for Web pages that can't be found. Now, with the rise of Internet censorship, Tim Bray is proposing a new HTTP code: 451, for Web servers and pages that are being censored,

Bray, a leading Google Android developer and co-creator of one of the first Web search engines, Open Text and XML, has proposed to the Internet Engineering Task Force (IETF) that code 451 be used for, "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."

Formally, this would be:

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 name of this code, Bray notes in passing comes from the late Ray Bradbury's classic science-fiction novel, Fahrenheit 451. In it, Firemen no longer fight fires, but start them to burn books. The title comes from the ignition point for paper.

Bray also credits Terence Eden, a well-known mobile software manager, for pointing out that there are no good Web error messages for censorship. Eden had noticed that when he tried to get The Pirate Bay, a BitTorrent file sharing site currently blocked in the United Kingdom by government decree, his ISP served "an HTTP 403 error." But, according to the World Wide Web Consortium (W3C) specifications, "The 4xx class of status code is intended for cases in which the client seems to have erred."

Eden continued, "Now, I haven't made an error when making this request. Furthermore: The server understood the request, but is refusing to fulfill it. In this case, the server did not even see the request. It was intercepted by my ISP and rejected by them on legal grounds." Therefore, none of the existing "error" codes fitted.

This isn't a new problem. Eden references an essay on the lack of Web censorship codes from 2008. Perhaps people are more aware of it as Internet censorship has grown more common.

Internet Censorship used to be seen as something outside the West. It was the Great Chinese Firewall; Middle-Eastern countries like Iran blocking access to Twitter and other specific sites or former dictatorships such as Egypt sealing off their entire Internet borders. Now, it's come home.

In the UK, ISPs were required to block access to The Pirate Bay by May 30. Web sites, like Megaupload are taken down by government agencies, and their users can't get to their own files. I think Bray is right. It is indeed time to let people know when a site they know and trust is actually unavailable for some technical reason and when it's been locked down by a government.

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