Oakland, California police recorded the license-plate numbers and locations of more than 1.1 million vehicles over a 3½-year period from 2010 to 2014, according to a report by the ArsTechnica tech-news site last week. The Oakland Police Department’s 33 automated license-plate readers scanned vehicles more than 4.6 million times during that period, recording the date, time, and their location and plate number.
The devices use optical character-recognition technology—like the early digital-era scanners used to convert printed documents to word-processing files—to check the plate numbers against a list of stolen or wanted vehicles. Like other forms of indiscriminate surveillance, they overwhelmingly track innocent people. In the first 16 months after the department began using the technology in 2006, barely one out of every 400 vehicles scanned matched one on the list of suspicious ones. In the period ArsTechnica looked at, the “hit rate” was 0.16%, less than one out of 600. In fact, the report says, almost all of the 100 most commonly spotted vehicles were Oakland police patrol cars.
Other cities using the technology include Los Angeles, Seattle, Minneapolis, Boston, and San Francisco, the ACLU and the Electronic Frontier Foundation are a appealing a court decision that denied them access to scanning data from the city police and county sheriff. In Seattle, police scanned plates more than 7.3 million times, according to records obtained by the American Civil Liberties Union of Washington in 2013—and got a “hit” for about one of every 1,000. “Or put another way, the Seattle Police Department photographed vehicles and recorded the exact time and location of the photo for individuals who were merely driving around in 7,369,416 instances,” the ACLU noted. Veteran Oakland police Captain Anthony Toribio said the technology was useful to his work.
“It’s a significant tool to have because it can speed up the investigative process by identifying vehicles, linking them to crimes, linking them to locations where that car has been flagged so to speak or identified by the LPR system,” he said. When he served as an area commander, he “used it frequently.” “We try to strategically place these cars in areas or beats that are high crime areas,” he said. Toribio cited an occasion when, as a result of a high incidence of burglaries in the hills of North Oakland, he once ordered an LPR-equipped car to that area. “Often times you have the suspects that are casing the area and driving around, and you never know when a cop car may drive by and they’re not doing nothing at that point, but a short while later they may be driving by, and it’s good to have that information.”
The main privacy issue is that the data make it easy to figure out where a car’s owner lives, works, and hangs out. In Seattle, the ACLU was able to track the routes of the police officers operating the scanners—and when and where they stopped for lunch.
In Oakland, ArsTechnica guessed which block City Councilmember Dan Kalb lived on less than a minute after he let them go through his data. “I knew these things existed, but I had not delved into the level of detail that you’re sharing with me,” Kalb told ArsTechnica. “My awareness is that we have something like this, these mobile LPRs, and I presumed that their primary purpose was to track down stolen vehicles or assist in the investigations of other crimes that knowing the license plate would help. It raises the question: What’s the purpose of retaining records for a long period of time?”
Courts have so far not made a specific ruling on the technology. The main legal standard, from the Supreme Court’s 1983 decision in United States v. Knotts, is that “a person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements.” In other words, if you’re driving around, you’re putting your license-plate number and your car’s appearance in a place where anyone can see it. Big-data technology, however, adds a new dimension, as it can provide a comprehensive, long-term, and easily searchable record of a car’s movements. “But left unchecked, these systems can put privacy at risk,” wrote Jamela Debelak, the ACLU of Washington’s technology and liberty director. “We shouldn’t turn a blind eye to the dangers of government collecting this massive amount data without any restrictions on use. Large quantities of data left in the hands of government are susceptible to abuse.” Oakland has no rule for how long it keeps records of the license plates scanned, but it deletes old data to free up storage space, apparently after three or four years. The Minnesota state police delete them after 48 hours, according to an ACLU report obtained by ArsTechnica, while Boston and Ohio’s Franklin County (Columbus) retain them for 90 days. Others hang on to them for much longer. County police hold them for 18 months in Charlotte, North Carolina, and two years in Los Angeles and the Dallas suburb of Plano. New Jersey and the Delaware Department of Homeland Security keep them for five years. “If I’m law enforcement, I would keep it forever,” Brian Owsley, a former federal judge turned law professor at Indiana Tech, told ArsTechnica. “That’s the privacy advocates’ concern is that this stuff goes into a database—gigabytes are essentially free now—and this stuff stays forever.”