451 Unavailable For Legal Reasons
The 451 HTTP response status code is used by the server to inform that the requested content cannot be accessed due to legal restrictions or compliance with laws.
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Introduction
In Action
Sample
Conclusion
Introduction
The HTTP response status code 451 Unavailable For Legal Reasons is used by the server to inform that the requested content cannot be accessed due to legal restrictions or compliance with laws. By default, the response is cacheable, but specific HTTP caching headers can be included to modify this behavior.
Furthermore, the HTTP status code 451 Redirect is utilized by Microsoft Exchange ActiveSync when the client is trying to connect to the incorrect server or if there’s a more efficient server available to access the user’s mailbox.
In Action
The HTTP response status code 451 Unavailable For Legal Reasons is used when the server refuses access to a resource based on legal demands, without confirming or denying its existence. It is often associated with censorship and can apply to various scenarios such as copyright infringement, privacy violations, or court-ordered restrictions.
This status code allows for transparency in tracking the number and types of sites that are blocked due to legal reasons, and it includes a Link header to identify the party responsible for blocking the content.
Clients may still access the resources through alternative methods like VPNs or proxy servers. In a different context, the HTTP status code 451 Redirect is used by Microsoft Exchange ActiveSync to indicate that the client is trying to connect to the wrong server, and it may provide a new address to use for subsequent requests.
Sample
In the example, when the client requests a resource, the server responds with the 451 Unavailable For Legal Reasons.
This means that the server is refusing to provide access to the requested resource due to legal demands or censorship, without confirming or denying the resource’s existence.
Request
GET /tech-trial-updates HTTP/1.1
Host: www.example.com
Response
HTTP/1.1 451 Unavailable For Legal Reasons
Link: < https://www.example.com/legaldept>; rel=”blocked-by”
Content-Type: text/html
Content-Length: 174
< html>
< head>
< title>Publication Ban< /title>
< /head>
< body>
< p>The content that you have requested is unavailable due to a government-ordered publication ban.< /p>
< /body>
< /html>
Conclusion
The 451 Unavailable For Legal Reasons status code indicates that the requested resource is blocked due to legal demands or censorship. The server neither confirms nor denies the resource’s existence, providing transparency about the restriction and allowing easier collection of statistics related to blocked content.
