451 Unavailable For Legal Reasons

What is a 451 Unavailable For Legal Reasons HTTP response?

Usage of the 451 HTTP status response code is suitable for situations where a resource must be blocked for legal reasons, such as where a court judgement or law requires that content should be made unavailable.

451 has been used widely by US news/media sites following the introduction of EU ‘GDPR’ privacy regulations, blocking content for EU visitors.

The 451 HTTP status was actually only introduced quite recently in 2016 – in order to provide more information than previous alternatives such as 403 forbidden.

What type of HTTP status is a 451?

A 451 is in the 4xx class of status codes which are client error based.

Example 451 response

Example of a 451 HTTP response shown to EU website users
Example 451 response in the Chrome network tab

When should a 451 response be used?

A 451 response is suitable for any situation whereby a court or other legal entity has mandated that a web resource must be removed or blocked.

Examples might include: criminal court cases, civil court cases, tribunals, statutes/laws, treaties, or simply a request from a company legal department.

A 451 response does not necessarily have to be served globally. For example many US news sites show a 451 status and message to European users to get around GDPR privacy requirements.

Does a 451 HTTP status affect SEO?

If you want to block all users for legal reasons – then a 451 code is perfect – and will also likely remove your site from search engines.

If Google are unable to access a resource it is likely that they will not index it. If all users/bots that attempt to access a resource are served with a 451 response and no content, it will not be indexed.

However from testing conducted at the time of writing: if US users and Googlebot are able to access the content then this content will be indexable/potentially available in Google search.

Content last checked for accuracy and updated: 12th July 2020, by Colin McDermott

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