The State Of Surveillance

Lost in the recent London bombings, along with innocent lives, was any illusion that today's surveillance technology can save us from evildoers. Britain has 4 million video cameras monitoring streets, parks, and government buildings, more than any other country. London alone has 500,000 cameras watching for signs of illicit activity. Studying camera footage helped link the July 7 bombings with four men -- but only after the fact. The disaster drove home some painful reminders: Fanatics bent on suicide aren't fazed by cameras. And even if they are known terrorists, most video surveillance software won't pick them out anyway.

Tomorrow's surveillance technology may be considerably more effective. But each uptick in protection will typically come at the cost of more intrusion into the privacy of ordinary people. For now, the public seems to find that trade-off acceptable, so scientists around the world have intensified efforts to perfect the art of surveillance, hoping to catch villains before they strike.