XML creator Tim Bray has proposed a new HTTP error code: 451, "Legally restricted." The idea is to create an unambiguous code that ISPs can return when a user requests a page that has been censored by a court or government. Note the specific number of the error code. Bray thanks Ray Bradbury in the footnotes.

451 Unavailable For Legal Reasons

This status code indicates that the server is subject to legal restrictions which prevent it servicing the request.