“Network filters are universally loathed. Duh. no one’s ever written a regular expression that can distinguish art from porn, and no one ever will. [..] The web's got about 100 billion page on it; if you have a fail-rate of one-tenth of 1 percent, you'll overblock (or underblock, or both) 100,000,000 pages. That's several ‘Library of Congress’ worth of pointless censorship, or all the porn ever made, time 10, missed though underfilterring. You'd be an idiot to even try.” — Cory Doctorow : “Petard: A tale of just deserts” in MIT Technology review SF annual 2014 : Twelve tomorrows