Increasingly, Internet providers are being instructed by courts to block access to websites. This measure is often applied against copyright infringing sites, but not always with a proper explanation. The Internet Engineering Task Force (IETF) just approved a special HTTP status code for these type of legal demands, Error 451.

Domain name blocking has become one of the entertainment industries’ go-to methods for reducing online copyright infringement.

Blocking requests from both the music and movie sector are widespread around Europe, with The Pirate Bay has being one of the main targets.

At the moment all ISPs use different notifications to show that a website is blocked. In the UK for example, Virgin, BT and Sky all have a custom message, some being more descriptive than others.

This issue prompted Tim Bray to suggest a special HTTP status code for legal blockades. He noticed that some ISPs were using the “403 Forbidden” code for a Pirate Bay block, which is not what it was intended for.

After a long review process the Internet Engineering Task Force (IETF) has now approved this new HTTP status code.

There is no obligation for ISPs or other parties to use the new status. The 451 Unavailable project suggests that ideally it should be used to provide the public with additional details including a copy of the court order.

“A really good Error 451 message would tell their customers how to challenge a block, how long the block’s expected to last, where the relevant legal documents are and which legal authority imposed the blocking order,” they write.

The 451 Unavailable group says it will encourage ISPs to show 451 errors for legal blockades and it eventually hopes to reduce the scope of widespread blocking.

Interestingly, the most recent 451 draft already gives people some suggestions how to bypass court ordered blockades on their own, mentioning VPNs and Tor as possible workarounds.

“Note that in many cases clients can still access the denied resource by using technical countermeasures such as a VPN or the Tor network.”

While some HTTP errors numbers were arbitrarily chosen, 451 refers to Ray Bradbury’s dystopian novel Fahrenheit 451 which is about censorship and suppression of information.

In general, more openness about court ordered blockades is welcome, especially because the process is too often shrouded in secrecy. That said, the day that the web gets a special HTTP status code for censorship is hardly something to celebrate.