Police departments around the country have been compiling databases on the travels of innocent motorists. The tracking is made possible by automated license plate reader technology (ALPR, also known as ANPR in Europe), the deployment of which is backed by funding from federal gas tax dollars appropriated without any public debate or oversight.

The American Civil Liberties Union yesterday announced a campaign to increase transparency in the way ALPR is used. The liberal activist group used its network of affiliates to blanket local, state and federal law enforcement offices with freedom of information requests designed to force disclosure of key documents that may shed light on what is currently being done with the devices.

A standalone ALPR system is essentially the same as speed camera without the radar speed sensor. A video camera records every passing vehicle while optical character recognition software reads the license plate and looks up the vehicle's owner. Instead of issuing that person a ticket, the device records the time and date his vehicle drove past and stores it in a searchable database. The systems are so similar that photo enforcement vendors already use their automated ticketing machines to perform ALPR services for municipal customers.

"As ALPRs increasingly blanket American roads and highways, they raise the prospect of pervasive and prolonged surveillance of Americans' movements, a problem exacerbated when law enforcement agencies keep data about people not suspected of wrongdoing, and when data from discrete ALPR systems is pooled together into state, regional and even national databases," ACLU staff attorney Catherine Crump wrote Monday in the group's request to the US Department of Transportation.

The ACLU wants six years worth of records regarding the purchase of ALPR devices, their use, department policies and how the information is stored and shared. The group is trying to get agencies to reveal just how widespread the tracking has become and for how long the information is kept. Most importantly, the group wants to know precisely who ends up with access to this information.

"It's not an exaggeration to say that in ten years there will be ALPRs just about everywhere, making detailed records of every driver's every movement, and storing it for who knows how long," wrote Kade Crockford, Director of the Technology for Liberty Project of the ACLU of Massachusetts, in a blog posting explaining the effort. "In some cases, we know that the worst-case scenario -- vast databases with records of movements of massive numbers of people -- is already happening. To avoid this fate we need to convince the nation and our lawmakers to take action on this serious threat to our liberty. And to make a convincing case, we need to know a lot more about the problem as it stands."

Widespread use of ANPR in the UK has resulted in a large number of innocent drivers being stopped over insurance verification problems. AA reported in 2010 that it received 20 "mistaken identity" calls per week, mostly generated by errors in the recognition of characters like O and 0 on a license plate. In at least one case, the mistake turned deadly. On May 19, 2008 a Northumbria, UK police officer engaged in hot pursuit of a vehicle that had been flagged by the plate recognition system. While speeding through the neighborhood, the officer struck and killed sixteen-year-old Hayley Adamson. It turns out that the database information that triggered the alarm was incorrect and the car being chased was had done nothing wrong.