451 Unavailable For Legal Reasons HTTP Status Code


HTTP status code 451, titled "Unavailable For Legal Reasons," is utilized to indicate situations where access to a particular resource is denied due to legal demands or restrictions. The code was inspired by Ray Bradbury's dystopian novel "Fahrenheit 451," where books are outlawed and burned by authorities. It provides a mechanism for web servers to convey to the requester (typically a web browser or client) that the requested resource cannot be served not due to technical difficulties or issues, but as a result of legal constraints, such as copyright claims, court orders, censorship demands, or government-imposed internet restrictions.

When a web server returns a 451 status code, it is expected to include an explanation in the response body about the specific legal restriction or demand that prevents the resource from being accessed. This not only informs the user about the reason for the denial but also ensures transparency regarding the legal forces at play behind the scenes. The inclusion of such details can help users understand the legal landscape and potentially seek alternative avenues to access the content or challenge the restriction if feasible.

It's important to note that while the 451 status code makes the legal landscape more visible on the internet, it doesn't solve the underlying issues of censorship or legal overreach. However, it does provide a standardized way for expressing these legal barriers in the digital space.


451 Unavailable For Legal Reasons

Common Causes

Here are the primary causes for this status code:

  1. Legal Censorship: The resource is made unavailable due to government orders to comply with censorship laws. This can include content that is considered illegal in a particular country or region, such as certain political content, information deemed to be a threat to national security, or web pages that violate local laws.

  2. Copyright Issues: Content that infringes on copyright laws may also lead to a 451 error. This is particularly relevant for websites that host or link to copyrighted material without authorization.

  3. Court Orders: Specific court orders demanding the removal of content can result in a webpage being inaccessible and returning a 451 status code. This can be due to defamation, privacy issues, or other legal considerations that a court deems valid for the removal of content.

  4. Government Regulations: In some cases, broader government regulations that require the blocking or removal of certain types of content (e.g., content promoting hate speech, extremism, or adult content in regions where such material is illegal) can be a cause.

  5. Internet Regulations Policies: Some countries have specific internet regulation policies that mandate the blocking of certain types of content. Compliance with these policies can result in a 451 error.

The use of Status Code 451 is an effort to differentiate cases where content is legally compelled to be removed from other types of errors (like the 404 Not Found or 403 Forbidden status codes). It serves as a notice that the unavailability of the content is due to legal reasons, rather than technical issues or unauthorized access attempts.

Browser Support

The following table will show you the current browser support for the 451 Unavailable For Legal Reasons HTTP status code.

Edge Chrome Firefox Opera Safari
Tablets / Mobile
Chrome Firefox Opera Safari Samsung Webview

Last updated by CSSPortal on: 1st April 2024