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Automatic License Plate Readers: Persistent Privacy Invaders with a 0.0047% Hit Rate that Don’t Stop Crime

The American Civil Liberties Union has recently released a report showing that license plate readers, mounted on police cars and designed to automatically scan plates and pull up associated driver information:

  • Are present in all 50 states of the USA;
  • Add information to identify where cars are located and when they were located there;
  • Are gathered without a warrant;
  • Generate records that are regularly deleted only by a few states and municipalities, and otherwise turn into a tracking database with millions of data points in other American communities;
  • Are often used as a data source for “fusion centers“: regional offices that siphon up local data and add it to a growing national tracking database on Americans;
  • Are also used as a data source for corporations like the National Vehicle Location Service that use the data in contracts to gain a profit;
  • Overwhelmingly identify the whereabouts of innocent people, as this represent graphic for Maryland’s program shows:
    ACLU reports: for every million plates read by police LPR units in Maryland, there are only 2,000 hits, most for expired registrations or emissions certificates, and only 47 for serious crimes

Additional information outside the ACLU report indicates that, privacy concerns aside, the license plate scanners just don’t work:

  • Are not effective, according to the U.S. Government’s own website for “evidence-based crime prevention.” rates License Plate Reader Technology in red as NOT EFFECTIVE based on the only two experimental studies regarding the tech to date. Both of these studies found that the use of license plate scanners failed to cut the incidence of crime rate where they were used.
  • Are also found to be largely ineffective in a new experimental study of license plate scanning by police in in Mesa, Arizona with results published in The Journal of Experimental Criminology a month ago. Use of automatic license plate scanning, manual searches of license plate numbers, or neither technique was randomly assigned to an area. Neither form of license plate scanning was associated with a statistically significant decline in police calls in auto theft, or personal crimes, or property crimes, or disorder crimes, when compared to control areas of no treatment. Only for one of five crime types (drug crimes) was there any statistically significant difference — with automatic license plate scanning associated with a decline in police calls but manual license plate scanning associated with an increase in police calls.
    Table 3 from Koper et al 2013 on license plate readers
    Why were drug offenses, but only drug offenses, lowered by the use of license plate scanning cameras? It wasn’t the collection of massive databases of personal information about innocent Americans’ whereabouts that did the trick, according to the authors. It was something else, something more simple and trivial:

    “It would seem that the decline in drug calls at the LPR locations was due to the deterrent value of displaying the cameras rather than the identification and incapacitation of offenders…. When the officers had the LPRs activated, they spent more time doing fixed surveillance in prominent locations along the hot routes. This may have driven away prospective drug buyers who were traveling to these locations for drug purchasers.”

    That kind of deterrence can be achieved with a $50 fake camera mounted to a police hood, and doesn’t require any invasion of innocent Americans’ privacy.

If there is no clear evidence that license plate scanning lowers crime, if the practice leads to the massive and persistent invasion of Americans’ privacy from government snooping, and if scanning units cost $20,000 – $25,000 apiece, why does license plate scanning continue?

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