Error 451: Now It's Easy to Find out If a Page Has Been Censored

The traditional 404 is not only more frustrating because some sites (like Disqus, do the test) are quite creative in page warnings not found. But not always the page is missing: sometimes the 404 code (or others, such as code 403) appears in place that addresses actually were censored. Now there is a specific HTTP code for these cases: 451.
This code was proposed in 2013, but now the members of the Internet Engineering Steering Group (IESG) – a group responsible for setting certain standards on the Internet – approved the adoption. No wonder: they had to evaluate several factors to find out whether the creation of this code makes sense. And does. The goal is consistent with an aspect that is becoming increasingly important: transparency on the web.
The idea is simple. When you encounter the error 451, you will know at the time that that page is inaccessible as a result of a court order or any prohibition imposed by authorities of any country. The meaning summarized code 451 is “Unavailable for Legal Reasons” (“Unavailable for Legal Reasons” in free translation).
In addition to the HTTP code itself, it is expected that the page give some explanation of the reasons for the blockade, including where authority determined the unavailability of the content, the law has been violated, which the order of context and so on. The important thing is to be clear to the user that legal aspects (or, depending on the circumstances, politicians) are preventing access to the page, not technical problems.
Why “451” and not another number? The explanation is very interesting. This code was chosen in reference to science fiction book Fahrenheit 451, Ray Bradbury. In the work (which also won an adaptation for the film), firemen have the mission to destroy books on the grounds that reading causes unhappiness in people and generates differences of opinion.
There could be no allusion best, no? The 451 also corresponds to the standards of codes already adopted. The 4xx series, for example, concerns unavailable content (404: Page Not Found, 403: prohibited content, among others), 5xx errors often refer to server problems (such as error 503: service unavailable), and Here it goes.
A simple status code will not put an end to censorship on the Internet, but will help to measure the extent of the problem. The IESG itself recognizes that some governments may hinder the adoption of the code 451 just to cover abusive actions. On the other hand, nothing will prevent the new code to be used by Google, GitHub and many other companies that are required to block content on their services for reasons beyond the reasonable.
code settings still need to go through some reviews, but according to the IESG, the error 451 can now be displayed in locked pages.
With information: The Verge
Updated on 22/12 at 9:00: although the unavailability of content for policy issues are among the reasons for the creation of the 451 code, it is important to note that not every block can be considered censorship. If a page exposes the intimacy of an unauthorized person or promotes racist speeches, for example, there is not there any excess by the authorities, on the contrary: the blockade is an expected action. In these circumstances, the code 451 has the function of informing the visitor that address is inaccessible for violating laws or characterize a crime.