mnot’s blog: Why 451?
www.mnot.net/blog/2015/12/18/451
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Tim Bray brought this draft to the HTTP Working Group some time ago, because he (and many others) thought it was important to highlight online censorship; the 403 status code says "Forbidden", but it doesn't say "I can't show you that for legal reasons." Hence, 451 (which is also a great tip of the hat to Ray Bradbury).