Web blocking in the United Kingdom

The precise number of websites blocked in the United Kingdom is unknown. Blocking techniques vary from one Internet Service Provider (ISP) to another with some sites or specific URLs blocked by some ISPs and not others. Websites and services are blocked using a combination of data feeds from private content-control technology companies, government agencies, NGOs, court orders in conjunction with the service administrators who may or may not have the power to unblock, additionally block, appeal or recategorise blocked content.

There are a number of different web blocking programmes in the UK. The high-profile default ISP filters and IWF filters have been referred to as a "pornwall", "porn filter", "Hadrian's Firewall", "Great Firewall of Britain" and the "Great Firewall of Cameron". However the programmes are usually referred to interchangeable or individually rather than collectively.

Inciting racial hatred was removed from the IWF's remit on the setting up of a police website for the purpose in April 2011.

The technical measures used to block sites include DNS hijacking, DNS blocking, IP address blocking, and Deep packet inspection, making consistent verification problematic. One known method is ISP scraping DNS of domains subject to blocking orders to produce a list of IPs to block.

The Open Rights Group has proposed adding the new HTTP status code '451' to help streamline and add transparency to the process of determining when a site is blocked.

It is an established procedure in the UK for rights-holders to use 'Section 97' court orders to require ISPs to block copyright-infringing sites. For instance, court orders obtained by the BPI in October 2013 resulted in the blocking of 21 file-sharing sites including FilesTube and Torrentz. There is a private agreement in principle between leading ISPs and rights holders, made with encouragement from government, to quickly restrict access to websites when presented with court orders. The court orders are not made public and "overblocking" is sometimes reported, such as the accidental blocking of the Radio Times, Crystal Palace F.C., Taylor Swift and over 100 others websites in August 2013.

...
Wikipedia