Yes. 4xx codes are client errors: The request contains a mistake or can't be fulfilled as sent.

4xx · Client error

HTTP 451 Unavailable For Legal Reasons

Blocked for legal reasons, such as a court order. The number references Fahrenheit 451.

Example response

HTTP

HTTP/1.1 451 Unavailable For Legal Reasons
Content-Type: application/json; charset=utf-8

{ "error": "Unavailable For Legal Reasons" }

Look up the headers shown here in the HTTP headers reference.

What does HTTP 451 mean?: Unavailable For Legal Reasons. Blocked for legal reasons, such as a court order. The number references Fahrenheit 451.
Is 451 an error?: Yes. 4xx codes are client errors: The request contains a mistake or can't be fulfilled as sent.