[hawleyal]

That is a dumb error code.

404 already exists.

[ceejayoz]

404 is for "not found". 451 would be for "found, but we can't show it to you".

[dragonwriter]

> 451 would be for "found, but we can't show it to you".

"The server understood the request, but is refusing to fulfill it" is already 403.