What Are License-Plate Readers Good For?
Following its mandate to counter acts of terror and respond to related threats, the Bay Area Urban Areas Securities Initiative (UASI), a regional organization funded by a Department of Homeland Security grant program, has poured hundreds of thousands of dollars into automatic license-plate readers (ALPR) for local police across Northern California over the past few years.
But newly released numbers from the Bay Area’s UASI suggest that the vast majority of drivers’ location data, tracked and retained through ALPR programs, have not been linked to any terrorist activity or violent criminal activity.
ALPRs combine high-speed cameras with analytic image software, collecting the plate numbers of cars passing by specialized recording points. Those plate numbers are then typically compared against “hot lists” of people who law-enforcement agencies have interest in.
Last month, the Bay Area’s UASI released ALPR data from the Central Marin Police Authority showing that only .02% of the nearly 4 million license plates tracked over October of 2015 through April of this year resulted in matches to any police “hot list” databases. The data indicate that zero “known or suspected terrorists” have been tracked using ALPRs, and that only a handful of other matches related to other hot-list criteria.
Similar surveillance-to-threat disparities have been found in ALPR programs across the country. According to a 2013 American Civil Liberties Union report, only 47 of every million license-plate scans captured in Maryland and funneled to the state’s DHS-affiliated fusion center were linked with serious criminal cases involving car thefts, wanted persons, violent gang or terrorist organizations, sex offenders, or Maryland’s warrant-flagging program. Digging back further, the ACLU also found that, over January 2012 through March 2012, the Rhinebeck Police Department in New York had just a 0.01% hit rate for 99,771 plates scanned. Similarly, over August 2011 through June 2012, the High Point Police Department in North Carolina had only a 0.08% hit rate for 70,289 plates scanned.
Despite these small percentages of hits, however, law-enforcement officials say that ALPR technology remains essential for criminal investigations.
“If people could let me know which cars the criminals were driving, I would only look at those vehicles,” says Mike Sena, the director of the Northern California Regional Intelligence Center (NCRIC), which works with several local police departments using ALPRs. “The majority of the stats you see in that [Bay Area UASI] report are those that are just that quick hit, that quick alert... . But to me, the greater piece of that is giving the investigator a starting point when he comes up with that murder or violent crime… .”
In other words, ALPRs can give law enforcement important leads to follow when attempting to identify where suspects were at a given time. Sena notes, however, that it is impossible to quantify how often automatic license-plate readers help in this process, since detectives do not necessarily document every time license-plate data is used to determine the location of a persons of interest.