HTTP 451 unavailable for legal reasons

What 451 means

451 Unavailable For Legal Reasons is the HTTP status code that says "the server is deliberately refusing to serve this resource because of a legal demand". It was proposed in 2015 and standardised in RFC 7725, named for Ray Bradbury's *Fahrenheit 451*. The operator is not saying the content does not exist, and is not saying the visitor is forbidden on identity grounds; it is saying a court order, a takedown notice, a data-protection removal, or a country-specific law removed or blocks this resource.

RFC 7725 asks servers to include a Link header pointing to the source of the legal demand when it can be shared:

HTTP/1.1 451 Unavailable For Legal Reasons
Link: <https://www.example.com/legal-notices/2016-01/451-takedown>; rel="blocked-by"
Content-Type: text/html

When sites actually send it

• Copyright or defamation takedowns where the content is taken down but not deleted, so the difference between an old 404 and a legal block matters for transparency.
• Privacy and data-protection orders, for example a "right to be forgotten" removal where the URL must stop being served.
• Jurisdiction-based requirements: content a regulator or a court requires the platform to block for legal reasons, distinct from a blanket block of a territory that is a commercial choice.
• Government-mandated blocking: blocked content in some territories returns 451 where the platform is required by law to hide it.

How it differs from the other refusals

The point of 451 is honesty and transparency: it lets a request tell a crawler "this resource exists but cannot be served", which matters for journalists, indexed archives, and compliance dashboards. It is the only code whose meaning is explicitly a legal trigger.

The operational nuance

• If your hosting or CDN maps certain blocked resources to 451, make sure the Link header exists where a named legal notice does, and make sure nothing accidentally flips a block that is a court order into a silent 404 (a removal for legal reasons and a site edit are two different events).
• Crawlers treat 451 like the other 4xx non-success codes: the resource is not in the index. For a GDPR-visible removal or a takedown, keep the legal-copy landpage live under a 200 while the content route returns 451.
• In most WordPress/hosting stacks 451 requires a theme response filter or a reverse-proxy rule; it is not a code your panel can click. When the law is doing the work, the legal request is the authority: keep the copy clean, the Link header accurate, and let the removal be the event the servers, not the CMS, enforce.

Reference

See the full status code reference for where 451 sits between the 4xx family and the redirects.