Error 451: New HTTP code to show that sites are censored
December 25, 2015
“This status code indicates that the server is denying access to the resource as a consequence of a legal demand,” said IETF in a statement.
The 451 HTTP error code was first proposed in 2012 as a tribute to Ray Bradbury’s classic novel Fahrenheit 451, and was suggested by former Google engineer Tim Bray, XML specification author.
The code 451 can be used by a website such as Facebook or Twitter, and also by network firewalls and even Internet Service Providers (ISPs). The idea behind 451 is to let users know that their government is blocking specific content on a website.
For example, a government regulatory body may want to block torrent or illegal media streaming sites, or simply censor what they don’t like with a page showing Error 451. Whatever the reason, at least the citizens will know that the website itself isn’t to be blamed, but the fact that there are “orders” to not show content.
However, “it is possible that certain legal authorities might wish to avoid transparency, and not only demand the restriction of access to certain resources, but also avoid disclosing that the demand was made,” said IETF.
Democratic and semi-democratic countries are the most likely places where 451 will become useful. Take, for example, the U.K. government’s decision in 2012 to force ISPs to block torrent site The Pirate Bay. Instead of throwing up a 403 Forbidden code, ISPs could instead return 451 to make it clear why their customers can’t see specific content.
The U.K.’s decision to block The Pirate Bay and a blog post by Terence Eden on Slashdot is what inspired Bray to suggest 451 for the code. Bray said in a blog post at the time that the ultimate objective of the code is transparency.
“One of the things in the proposal is that the 451 Unavailable for Legal Reasons status is supposed to be accompanied by an explanation of what the legal restrictions are, and what class of sites they apply to.”
Mark Nottingham, chair of the IETF HTTP Working Group, welcomed the introduction of the code and said that “effectively you can start using it now.” However, he added that the organization cannot guarantee that all governments or ISPs will actually use it in cases of legal restrictions.
“By its nature, you can’t guarantee that all attempts to censor content will be conveniently labeled by the censor. Although 451 can be used both by network-based intermediaries (e.g., in a firewall) as well as on the origin Web server, I suspect it’s going to be used far more in the latter case, as Web sites like GitHub, Twitter, Facebook and Google are forced to censor content against their will in certain jurisdictions,” he said in a blog post.
“In some jurisdictions, I suspect that censorious governments will disallow the use of 451, to hide what they’re doing. We can’t stop that (of course), but if your government does that, it sends a strong message to you as a citizen about what their intent is.”