Error 451 is a new error code that we want ISPs to show when people visit websites blocked for legal reasons.
Courts can require ISPs to block access to certain websites. Showing the Error 451 message makes it clear when a website has been blocked after a court order.
In the UK, the websites that have been blocked so far have linked to content that infringes copyright.
In some countries, websites that contain material criticising the government are blocked. Access to the online work of journalists and opposition groups can be restricted.
Error 451 pages would include all the key information about the blocking order including links to the relevant court order, how to challenge the block and the law allowing the court to block websites in that country
A proposal for this 451 status code for use when resource access is denied due to legal demands has been made to the Internet Engineering Task Force.
451 Unavailable aims to be a repository for the legal documents that should be included on Error 451 pages and to provide legal analysis of those documents.