On Internet search filters

Published yesterday on The Conversation (and likely to spread from there on previous experience): “Blocks just move child porn under the counter“. Cheeky comment self-censored out: if they’re so good at deciding which search queries relate to child porn, why don’t GCHQ apply these techniques to their stash of mass surveillance metadata?

This note profited from useful comments from David Chadwick (who suggested “under the counter” instead of my original “on the top shelf”) and Robin Mackenzie.