On June 11th,2012, Google proposed a new HTTP status code to indicate webpage contents which are not conform to law. The new HTTP status code is 451 Unavailable for Legal Reasons.

Google Android Developer Advocate Tim Bray submitted the draft for the new HTTP status code, it will be used on some webpages which can not be served because of legal reasons. Visitors will know that the page cannot be seen because of the government censorship.

According to the draft, 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.

Before this, British ISP used the code 403 Forbidden when they conformed to the court order  to block Pirate Bay. Some blogs pointed out that 403 code represents "The server refuses to execute the request", but indeed, the Pirate Bay server didn't receive any requests, so 403 code is not appropriate here.

451 is optional according to Tim Bray. We may see this code in the future when we surfing the Internet for some contents. For the detailed draft, please visit : http://www.tbray.org/tmp/draft-tbray-http-legally-restricted-status.html