New HTTP Status Code Identifies Online Censorship on the Web

The Internet Engineering Steering Group (IESG) has made it easier for Web users to identify censored content, which also intensifies privacy and transparency challenges for companies doing business in countries with online censorship.

On Dec. 18 the IESG announced a new HTTP status code, 451. HTTP status codes are used to classify data transactions between Web browsers and servers. Internet users rarely see them, although certain ones — like the 404 “page not found” code — are commonly displayed when server content is inaccessible.

Code 451 — which pays homage to Ray Bradbury’s novel “Fahrenheit 451” — indicates that content is unavailable due to “legal obstacles,” according to the IESG. That includes websites that are blocked by censorship authorities in particular countries.

As Mark Nottingham, chair of the committee that developed the 451 code, explained, the IESG introduced the code primarily in response to requests by Internet users who wanted an easier way to identify censored Web content in an automated fashion. Now, robots crawling the Web can systematically determine which sites are blocked for legal reasons.

This is good news for supporters of online privacy and transparency. It makes it easier to separate content that is unavailable for technical reasons from material that is deliberately blocked. In turn, it provides another way to identify instances of online censorship.

Meanwhile, for companies doing business online, the 451 status code may be both a useful resource and a challenge. On the one hand, it makes it easier for companies like Twitter and Google (GOOG) to indicate to users that they have been forced to censor content in particular jurisdictions, instead of just making it unavailable without explanation.

Yet at the same time, serving apps and delivering services in multiple countries has become a little more complicated. Greater awareness of censorship means users are more likely to hold companies accountable for blocking access to content in certain countries while making it available elsewhere. Before, censorship occurred behind the scenes and was difficult to identify in a systematic way, but the 451 code provides a way to start changing that.