From the PBS NewsHour
Spencer Michels, reporting
SPENCER MICHELS: Americans are used to being watched on closed-circuit TV. Cameras are ubiquitous, especially in large cities.
The video surveillance industry brings in $3.2 billion dollars a year, and it's expected to grow quickly, especially after the Boston Marathon bombings. At one business in San Francisco, 22 cameras continually watch employees and guests enter and leave the building and drive their cars into and out of the garage. It's all recorded for future use.
A guard monitors the cameras in real time, and one night recently, those cameras caught this scene: a woman employee going to her car on the street while a male watches her and starts to follow. As he circles back to her car, for some reason, he sees other vehicles approaching and he makes a quick exit.
Would the cameras have helped had there been a crime? Could their more obvious presence have prevented one? It's all part of today's debate over surveillance....
SPENCER MICHELS: Ozer maintains that San Francisco's cameras installed to prevent crime, like those in many other cities, have not achieved their goal. And she cites a study made by researchers at the University of California, Berkeley, led by assistant professor of information Deirdre Mulligan.
DEIRDRE MULLIGAN, University of California, Berkeley: What we found in San Francisco with respect to this set of cameras is that they didn't have the desired effect, which was really about reducing violent crime.
And one can imagine, if you deploy cameras, for example, to deal with terrorists, many terrorists are planning to die anyway, right, and the fact that they're being filmed in their moment of martyrdom isn't really going to deter them.
SPENCER MICHELS: Mulligan contends the police can't rely on cameras.
DEIRDRE MULLIGAN: You need people on the ground. There are millions of backpacks, right? And knowing when somebody puts down a backpack and whether or not that's a suspicious activity when you're miles away in a camera booth and you have been watching footage for eight hours that day is really a tall order....