If you work in government and are asked to remove content from websites (as a result of executive orders), please use the HTTP status code 451 instead of 404.
451 is the correct status code to use for these cases, and you'll be doing the rest of the country a service by using it.
Addendum: you should also include a Link header with the link relation "blocked-by" that "Identifies the entity that blocks access to a resource following receipt of a legal demand."
@ramsey I got a 451 last week, the first time I'd ever seen one. I'm afraid I don't remember which site I was trying to access, other than I'm pretty sure it was a US one.