DevKits
451

Unavailable For Legal Reasons

4xx Client Error

Last updated:

The resource is unavailable due to legal demands (censorship, DMCA, GDPR).

Description

The '451' code is a nod to Fahrenheit 451. Used to explicitly signal legal blocking rather than pretending the resource doesn't exist (404).

When to use

Return 451 when content is blocked due to legal reasons, ideally with a Link header pointing to the authority.

Specification

RFC 7725

Examples

HTTP response
HTTP/1.1 451 Unavailable For Legal Reasons
Content-Type: application/json

{"error":"Unavailable For Legal Reasons"}
Node.js (Express)
res.status(451).json({ error: "Unavailable For Legal Reasons" });
Go (net/http)
w.WriteHeader(http.Status451)
Python (Flask)
return jsonify({"error": "Unavailable For Legal Reasons"}), 451

Related status codes

403

Forbidden

The server understood the request and the client is authenticated, but access is refused.

404

Not Found

The server has not found anything matching the requested URL.

All 4xx codes

400 Bad Request401 Unauthorized403 Forbidden404 Not Found405 Method Not Allowed406 Not Acceptable408 Request Timeout409 Conflict410 Gone411 Length Required412 Precondition Failed413 Payload Too Large414 URI Too Long415 Unsupported Media Type418 I'm a teapot422 Unprocessable Entity425 Too Early428 Precondition Required429 Too Many Requests431 Request Header Fields Too Large451 Unavailable For Legal Reasons