HTTP status code 451 “Unavailable for Legal Reasons” indicates that access to a Web resource has been denied for legal reasons.
This code is used when a server cannot deliver the requested content due to legal restrictions, such as government censorship, court orders, or copyright violations.
The number 451 is a reference to Ray Bradbury’s dystopian novel “Fahrenheit 451,” in which books are banned.
Proposed in 2012 by Tim Bray and approved in 2015, this code offers more transparency than the generic 403 Forbidden error is an HTTP status code that indicates that the server understood the request but is not authorized to fulfill it, thus making the resources requested by the user available due to lack of permissions.
When you encounter a 451 error, it means that the content was intentionally blocked for legal reasons, not technical problems.
Examples of situations that can generate this error include censored web pages, content that violates privacy or blasphemy laws, or material considered a threat to national security.
The use of this code allows users to immediately understand that the inaccessibility of the content is due to specific legal restrictions.