In the United States, one of the most prominent examples was Tampa's use of facial recognition technology in 2001. But the city's police department dropped the technology two years later when it failed to result in a single arrest. The use of video surveillance was considered by the Oakland, Calif., police chief, but he ultimately found that "there is no conclusive way to establish that the presence of video surveillance resulted in the prevention or reduction of crime."
"They are good forensic tools — after something happens, they'll tell you what happened," said Jim Harper, the director of information policy studies at the Cato Institute. "And in the rare case where a terrorism case fails, they can be useful to help track down the perpetrators. But they do not provide protection against attacks, and that's a key distinction."
"We are not safer from terrorism with security cameras in our cities," said Harper. "Particularly terrorists who are willing to die, security cameras do not control their behavior. They would not stop them from planning to pull off an attack."
And Harper is concerned about the impact of widespread surveillance cameras on the privacy of Americans. "Cameras don't just watch criminals, but they watch everybody," he explained. "Someone visits their psychiatrist every Monday at two in the afternoon, traveling through public spaces. Where they're going is known to nobody, but a network of cameras could pull that out of obscurity. That info is known to government officials."
Another problem with the technology is that it sometimes shifts crime from one place to another. "If you're the owner of a 7-11 with a surveillance camera and someone robs the store next door to you, then that's a win for you but not for the police," said Bruce Schneier, a security consultant and the author of "Beyond Fear: Thinking Sensibly About Security in an Uncertain World."
Both Harper and Schneier believe that traditional law enforcement techniques are far more effective at preventing terrorism. "Generating human intelligence, targeted surveillance and breaking up terrorist cells — those have been proven to work," said Harper.
Most police chiefs regard the cameras as just one tool for cutting crime. "It's a technology bump for policing and justice," said John Firman, the director of research at the International Association of Chiefs of Police, who said that the issue will be discussed in a roundtable discussion at the IACP's annual conference in October. "We know cameras enhance that capacity but saying for sure that they reduced crime by 20 percent, that's another thing. Anecdotally, we know that they have had an impact."