In what is the most detailed article about license-plate scanners that I've seen to-date, Ars Technica starts with a report on how up-scale Tiburon, California, scans every car that transits the two roads into town, and then discusses the legal ramifications and potential risks of the technology. It's really an excellent piece and well worth a read to gain a good grasp of where we're likely to go as plate scanners pop up hither and yon, and what that's likely to mean for our privacy in terms of enhanced law-enforcement, government intrusions and abuses.
For starters, Cyrus Farivar writes:
Tiburon, a small but wealthy town just northeast of the Golden Gate Bridge, has an unusual distinction: it was one of the first towns in the country to mount automated license plate readers (LPRs) at its city borders—the only two roads going in and out of town. Effectively, that means the cops are keeping an eye on every car coming and going.
A contentious plan? Not in Tiburon, where the city council approved the cameras unanimously back in November 2009.
The scanners can read 60 license plates per second, then match observed plates against a "hot list" of wanted vehicles, stolen cars, or criminal suspects. LPRs have increasingly become a mainstay of law enforcement nationwide; many agencies tout them as a highly effective "force multiplier" for catching bad guys, most notably burglars, car thieves, child molesters, kidnappers, terrorists, and—potentially—undocumented immigrants.
There's a high creepy factor for those of us inclined in that direction, but the town boasts of some benefits that we'll have to take at face value.
Cronin explained that in a town like Tiburon, where the biggest criminal concern is property crime, knowing who is coming and going at odd hours has been very helpful to the squad. The chief added that, prior to deploying the cameras, crime was still relatively low—only about 100 to 120 thefts per year, he said. Since the cameras have been in place, that figure has dropped by "around a third," he said.
For intelligent, systematic criminals, I can easily see how license-plate scanners would be a deterrent. So would any intrusive tracking technology. Still, the town's police concede the risks.
[T]he system is not without flaws. It tends to yield numerous false positives because the hot list data received from the California Department of Motor Vehicles takes a long time to be updated—and because the system cannot distinguish out-of-state plates. This creates a problem if, for instance, California plate ABC123 has been reported as stolen and is on the hotlist, and then someone drives through Tiburon with Oregon plate ABC123. (Other LPR systems can distinguish the plates from different states.) ...
And he recognizes the system's easy susceptibility to abuse. "We could put our boss's plates in the system and every time she leaves town we could go get her golf clubs," he joked.
To prevent problems, only Cronin and Hutton can add plates to the hot list. Each time a plate is run for historical data by either an officer or requested by an outside agency, the requester has to inform the chief by e-mail. Requests are tallied in an annual report for the town council.
Elsewhere, as the article details, false positives have had some unpleasant outcomes. including a woman ordered out of her car at gunpoint in San Francisco in a stop later upheld by the courts. And license-plate tracking has also helped solve crimes, including a murder in New York.
As I've written and said on television, I have serious concerns about this technology. I have no doubt that it can help solve crimes. The same could be said of random home searches. But I think the dangers and likely abuses outweigh any potential gains.
But go read the Ars Technica piece and decide for yourself.