Schneier on Security
A blog covering security and security technology.
October 4, 2004
License Plate "Guns" and Privacy
New Haven police have a new law enforcement tool: a license-plate scanner. Similar to a radar gun, it reads the license plates of moving or parked cars and links with remote police databases, immediately providing information about the car and owner. Right now the police check if there are any taxes owed on the car, if the car or license plate is stolen, and if the car is unregistered or uninsured. A car that comes up positive is towed.
On the face of it, this is nothing new. The police have always been able to run a license plate. The difference is they would do it manually, and that limited its use. It simply wasn't feasible for the police to run the plates of every car in a parking garage, or every car that passed through an intersection. What's different isn't the police tactic, but the efficiency of the process.
Technology is fundamentally changing the nature of surveillance. Years ago, surveillance meant trench-coated detectives following people down streets. It was laborious and expensive, and was only used when there was reasonable suspicion of a crime. Modern surveillance is the policeman with a license-plate scanner, or even a remote license-plate scanner mounted on a traffic light and a policeman sitting at a computer in the station. It's the same, but it's completely different. It's wholesale surveillance.
And it disrupts the balance between the powers of the police and the rights of the people.
Wholesale surveillance is fast becoming the norm. New York's E-Z Pass tracks cars at tunnels and bridges with tolls. We can all be tracked by our cell phones. Our purchases are tracked by banks and credit card companies, our telephone calls by phone companies, our Internet surfing habits by Web site operators. Security cameras are everywhere. If they wanted, the police could take the database of vehicles outfitted with the OnStar tracking system, and immediately locate all of those New Haven cars.
Like the license-plate scanners, the electronic footprints we leave everywhere can be automatically correlated with databases. The data can be stored forever, allowing police to conduct surveillance backwards in time.
The effects of wholesale surveillance on privacy and civil liberties is profound; but unfortunately, the debate often gets mischaracterized as a question about how much privacy we need to give up in order to be secure. This is wrong. It's obvious that we are all safer when the police can use all techniques at their disposal. What we need are corresponding mechanisms to prevent abuse, and that don't place an unreasonable burden on the innocent.
Throughout our nation's history, we have maintained a balance between the necessary interests of police and the civil rights of the people. The license plate itself is such a balance. Imagine the debate from the early 1900s: The police proposed affixing a plaque to every car with the car owner's name, so they could better track cars used in crimes. Civil libertarians objected because that would reduce the privacy of every car owner. So a compromise was reached: a random string of letter and numbers that the police could use to determine the car owner. By deliberately designing a more cumbersome system, the needs of law enforcement and the public's right to privacy were balanced.
The search warrant process, as prescribed in the Fourth Amendment, is another balancing method. So is the minimization requirement for telephone eavesdropping: the police must stop listening to a phone line if the suspect under investigation is not talking.
For license-plate scanners, one obvious protection is to require the police to erase data collected on innocent car owners immediately, and not save it. The police have no legitimate need to collect data on everyone's driving habits. Another is to allow car owners access to the information about them used in these automated searches, and to allow them to challenge inaccuracies.
We need to go further. Criminal penalties are severe in order to create a deterrent, because it is hard to catch wrongdoers. As they become easier to catch, a realignment is necessary. When the police can automate the detection of a wrongdoing, perhaps there should no longer be any criminal penalty attached. For example, both red light cameras and speed-trap cameras all issue citations without any "points" assessed against the driver.
Wholesale surveillance is not simply a more efficient way for the police to do what they've always done. It's a new police power, one made possible with today's technology and one that will be made easier with tomorrow's. And with any new police power, we as a society need to take an active role in establishing rules governing its use. To do otherwise is to cede ever more authority to the police.
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