Britain claims roughly 4.2 million public surveillance cameras---about one for every 14 people, reports the BBC. As the devices proliferate in cities around the world, Denver is no exception: Local police plan to add 33 cameras to the 80 already in existence. They're useful in places such as East Colfax Avenue, Cherry Creek, and some Denver Public Schools, writes The Denver Post. So far, cameras have caught images of about 300 crimes in the past year and a half, aiding police in their efforts to take 80 suspected criminals off the streets. "We would like to put a cop at every corner. But in reality, who can put a cop at every corner?" says Lieutenant Ernie Martinez, who runs the program. "What we can do is use technology to leverage our assets and help out our officers." But Mark Silverstein, legal director for the American Civil Liberties Union in Colorado, is wary. He opines that monitoring people in real-time "erodes privacy, inhibits freedom, and chills expression in public spaces, with little or no benefit in reduced criminal activity."