Automated license plate reader (ALPR) systems are ever more popular as law enforcement tools, and it’s easy to understand why. With very little effort on the part of the operator, these systems can scan and record the time and place of sightings of thousands of license plates each day, and send an instant alert when a plate “of interest” is caught by the camera.
That thoroughness — and how the information is being used — is exactly what people are afraid of.
The concept of ALPR is simple even if the technology behind it is not. Multiple cameras — as many as six on a single vehicle or static installation — constantly scan for license plates as they come within view of the lens. Software recognizes the characteristic shape and placement of license plates and uses character recognition to translate the letters and numbers on the plate to a form the computer can interpret.
Vast Volumes of Information
That character string is instantly compared to a list of as many as several thousand license plates that are loaded into the computer’s memory, and an alert sounds if the string matches one in the list. At the same time, whether the plate is a listed one or not, the computer records the license plate, a wide shot of the car it’s on, and the time and place of the observation into a disk file. Several lanes of traffic moving in both directions, as well as parked cars, are scanned at the same time.
The license plates on the alert list are typically those reported as stolen or associated with people with outstanding arrest warrants. The lists have been used in some states to enforce in-state vehicle registration laws for people who move in from other states but don’t bother to re-register their cars until the old plates expire, if at all. If the same out-of-state plate is seen regularly for more than a month (the typical grace period to register a car after moving into the state), it’s probably being garaged locally and is a candidate for local registration.
The recorded vehicle-plate-time-location information is also useful as a kind of FI card for cars. If Billy the Burglar says he hasn’t been in a certain victimized neighborhood for months, but your ALPR system places his car there at around the same time as some forced entries were made, his alibi gets weak.
Even if you don’t have suspects for a string of similar crimes, the ALPR data can be queried to show any vehicles that were recorded as within a quarter mile of the victim locations within an hour of the crimes. Any cars that consistently show up close to the scene of the crime are worth looking at more closely.
The Repo Man’s ALPR?
One ALPR manufacturer, Vigilant Video, has a different business model. Their systems are installed on cars and trucks operated by auto repossessors who scan parking lots for vehicles to be seized, but like other systems, they record every plate they see. Law enforcement agencies can request queries of their database for wanted vehicles in a geographical area. The same company sells law enforcement-specific systems.
Citizens like the idea of being able to keep tabs on your community’s frequent felony flyers, but they are not as warm to enforcement of vehicle registration laws and even unpaid traffic and parking tickets. Most people want their police to be efficient, but not too efficient, the excess occurring at about the point when they are getting caught for things they believe should be overlooked.
Can these records be used for purposes other than police investigations? Some states make nearly every piece of data recorded by a public agency a public record, which potentially exposes ALPR data. Could a private investigator obtain ALPR data to show the travels of a cheating spouse? If a private employer thought one of their workers was loafing on the job, could they query the ALPR database to see where their company’s vehicles were observed?
In Connecticut, several towns that shared their ALPR data were hit with a freedom of information records demand from the American Civil Liberties Union, and had to give up three years of data, totaling 3.1 million scans. Maine has a law on the books requiring a purge of ALPR data more than 21 days old, and local governments have enacted similar ordinances prohibiting long-term retention of the information.
Privacy is of increasing concern in a world where it’s more and more difficult to do anything without it being documented.
Police, being the custodians of some of the most sensitive information, have to be especially careful how they use it.
