In San Francisco, the results have been even less impressive. In the first three years after the city installed cameras, they helped police charge suspects in a grand total of six cases.
No one doubts that if you provide conspicuous video monitoring of high-crime spots, it can have a wholesome effect -- though it may only push the mischief a couple of blocks away. If you want to stop gangs from taking over a corner or chase thugs out of a park, a few well-placed cameras may be just the ticket.
But just because a camera works in one place doesn't mean thousands scattered all over town will produce similar results. Anti-crime technology, like everything else, is subject to diminishing returns.
Having a pit bull in your house may keep away burglars. That doesn't mean you should get one for each room. The more cameras, and the more cops watching the feeds, the more potential for waste.
But none of this seems to faze zealots like Chicago Mayor Richard Daley, who has said he intends to place the devices on "almost every block." It's easy to inflate their modest benefits while forgetting they carry a chronically high price.
Privacy ought to count as one of the costs. Most people don't seem to mind the Chicago cameras, though most people probably don't realize how often they show up on a TV monitor. But not everyone relishes the idea of living under endless, inescapable police surveillance.
The forced exposure might be acceptable if cameras were freeing us from the tyranny of criminals. Actually, it seems to have freed us from nothing.
In a Bible story that is synonymous with foolishness, Esau sold his birthright for a mess of pottage. But he looks wiser than we do. With surveillance cameras, we've given up money and privacy. And we didn't even get the mess of pottage.