Computer scientists have created a way of letting law enforcement tap any camera that isn't password protected so they can determine where to send help or how to respond to a crime. "It's a way to help people take advantage of information that's out there," says David Ebert, an electrical and computer engineer at Purdue University.

The system, which is just a proof of concept, alarms privacy advocates who worry that prudent surveillance could easily lead to government overreach, or worse, unauthorized use. It relies upon two tools developed independently at Purdue. The Visual Analytics Law Enforcement Toolkit superimposes the rate and location of crimes and the location of police surveillance cameras. CAM2 reveals the location and orientation of public network cameras, like the one outside your apartment. You could do the same thing with a search engine like Shodan, but CAM2 makes the job far easier, which is the scary part. Aggregating all these individual feeds makes it potentially much more invasive.