Bruce Schneier, the Tube, and Surveillance Cameras

I usually find myself nodding in agreement with Bruce Schneier's blog missives. But not in the case of surveillance cameras in public venues, which Schneier decries as "foolish":

I was going to write something about the foolishness of adding cameras to public spaces as a response to terrorism threats, but Scott Henson said it already: Homeland Security Ubermeister Michael Chertoff just told NBC's Tim Russert on Meet the Press this morning that the United States should invest in "cameras and dogs" to protect subway, rail and bus transit systems from terrorist attacks. B.S. Surveillance cameras didn't deter the terrorist attacks in London. They didn't stop the courthouse killing spree in Atlanta. But they're prone to abuse. And at the end of they day they don't reduce crime.

Fine. Let's imagine there were no surveillance cameras. Instead, city government posts a police officer on every street corner. Would there be complaints? If not, why would there be an issue about a video monitoring system? From a logical perspective, why would we not want to provide police officers with extended vision capabilities? After all, these are public venues we're talking about.

I'm certain that British authorities believe the surveillance system in the Tube is an invaluable asset. One commenter on Bruce's blog sums it up:

Cameras will provide some evidence of the crime and help the authorities back track to see if anyone helped them along the way. Perhaps a camera could capture a license plate number of a car that dropped off a suicide bomber. Perhaps that would lead to the arrest of other potential suicide bombers thus saving lives, perhaps your own. In this way, they do in fact prevent crime. Without them, more crimes are undeterred.

From a cost-benefit perspective, if a five million dollar camera system helps roll up one or more terror networks -- which are hell bent on the destruction of Western economies -- the expense will have been well worth it.

There are many facets to deterrence. And one aspect Bruce seems to have ignored is post facto   analysis. As the attacks in London demonstrate, surveillance systems in public areas can be plainly, starkly invaluable.