The Utility of Security Cameras

To camera or not to camera?

Cities everywhere have addressed this question, with varying answers. London has opted for near-saturation coverage. New York has broad coverage in certain parts of the city. But in other cities, such as San Francisco, the question has been contentious.

The San Francisco Chronicle recently reported on the efficacy of that city's 68 cameras. Researchers discovered little deterrent effect:

San Francisco's 68 controversial anti-crime cameras haven't deterred criminals from committing assaults, sex offenses or robberies - and they've only moved homicides down the block, according to a new report from UC Berkeley.

They looked at seven types of crime: larcenies, burglaries, motor vehicle theft, assault, robbery, homicide and forcible sex offenses.

The only positive deterrent effect was the [22 percent] reduction of larcenies within 100 feet of the cameras. No other crimes were affected - except for homicides, which had an interesting pattern.

Murders went down within 250 feet of the cameras, but the reduction was completely offset by an increase 250 to 500 feet away, suggesting people moved down the block before killing each other.

The cameras have contributed to only one arrest nearly two years ago...

As a result, some in law enforcement argue that the cameras are a waste of resources:

"In their current configuration they are not useful, and they give people a false sense of security, which I think is bad," said Police Commissioner Joe Alioto-Veronese. He added that previous studies of security cameras in other parts of the country have also shown that they do not deter violent crime.

But others argue that the system needs to be upgraded, not scrapped:

Kevin Ryan, director of the Mayor's Office of Criminal Justice, is pushing for the cameras to be monitored in real-time like they are in Chicago and other cities. Those police departments are often able to catch crimes in progress and immediately respond.

The value of security cameras, as I see it, is not as a preventive tool, although I think Ryan is right that a system like Chicago's, which is networked into a fusion center, is certainly more capable of preventing crime.

For most systems, the primary value of a security cameras is in supplying evidence. Also, after a major crime or terrorist incident - such as the 2005 London transit bombings - camera images can have a calming effect on the population, who can see and recognize the criminals/terrorists and feel assured that they have been positively identified and are no longer a threat.

It's reasonable to debate whether a network of cameras provides enough benefit to justify the cost, but we should be clear about what those benefits are.

(h/t to Bruce Schneier)

Update 2008-04-10: Washington DC is also in the midst of a controversy, regarding its plan to consolidate monitoring of its security cameras and to move to live-monitoring.