> Technology security expert and academic Pierluigi Paganini said if properly applied, facial recognition technology could have alerted security forces to the bombers at Brussels airport.<p>It would have alerted the authorities that one "guy who came from Syria" is in an airport. And some other guy in similar situation is in another airport, and 10 others are in bus stations, and 50 others in train stations across Europe, and 500 others are in malls, and so on.<p>The reason mass surveillance doesn't work is because there will be a <i>ton</i> of "similar" signals. Which ones do you know to go after? Remember, one of the Paris attackers was already on an "extremist" list. And the more governments overreact and start putting more and more people on such lists "just to be on the safe side", the harder it will get to stop any of those thousands of tens of thousands of people that may at one point be in a crowd of people.