YOU ARE BEING TRACKED
How License Plate Readers Are Being Used
To Record Americans’ Movements

July 2013

You Are Being Tracked:
How License Plate Readers Are Being Used
To Record Americans’ Movements
July 2013

American Civil Liberties Union
125 Broad Street
New York, NY 10004
www.aclu.org

Cover Photo: Newsbound/AP

Table of Contents
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
THE TECHNOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
LICENSE PLATE READERS POSE PRIVACY RISKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chilling effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Abusive tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Institutional abuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Discriminatory targeting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Sidebar: Pervasive, Permanent Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
LICENSE PLATE READERS ARE WIDELY USED BY STATE AND LOCAL LAW
ENFORCEMENT AGENCIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
License plate readers collect vast quantities of data on innocent people . . . . . . . . 13
Many agencies retain data on innocent Americans for long periods of time . . . . . 16
All the pieces are lining up for widespread sharing of license plate reader data . . 18
Sidebar: Pushing Back on Invasive License Plate Reader Use: A Success Story . . 23
THE FEDERAL GOVERNMENT IS FUELING STATE AND LOCAL USE OF LICENSE
PLATE READERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
TOO LITTLE IS KNOWN ABOUT THE FEDERAL GOVERNMENT’S OWN USE OF
LICENSE PLATE READERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
PRIVATE COMPANIES COLLECT LICENSE PLATE DATA WITH NO OVERSIGHT . . . . . . . . 28
Sidebar: Data Mining License Plate Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
THERE ARE TOO FEW RULES IN PLACE TO PROTECT PRIVACY . . . . . . . . . . . . . . . . . . . . 31
RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
ACKNOWLEDGMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

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INTRODUCTION
If you’ve never seen an automatic license plate reader, it’s probably because you didn’t
know what to look for. The devices have been proliferating around the country at
worrying speed. Mounted on patrol cars or placed on bridges or overpasses, license
plate readers combine high-speed cameras that capture photographs of every passing
license plate with software that analyzes those photographs to identify the plate number.
License plate reader systems typically check each plate number against “hot lists”
of plates that have been uploaded to the system and provide an instant alert to a law
enforcement agent when a match or “hit” appears.

PHOTO: SPARKY

License plate readers would pose few
civil liberties risks if they only checked
plates against hot lists and these
hot lists were implemented soundly.
But these systems are configured
to store the photograph, the license
plate number, and the date, time, and
location where all vehicles are seen
— not just the data of vehicles that
generate hits. All of this information
is being placed into databases, and
is sometimes pooled into regional
sharing systems. As a result, enormous databases of motorists’ location information are
being created. All too frequently, these data are retained permanently and shared widely
with few or no restrictions on how they can be used.
The implementation of automatic license plate readers poses serious privacy and other
civil liberties threats. More and more cameras, longer retention periods, and widespread
sharing allow law enforcement agents to assemble the individual puzzle pieces of where
we have been over time into a single, high-resolution image of our lives. The knowledge
that one is subject to constant monitoring can chill the exercise of our cherished rights
to free speech and association. Databases of license plate reader information create
opportunities for institutional abuse, such as using them to identify protest attendees
merely because these individuals have exercised their First Amendment-protected right
to free speech. If not properly secured, license plate reader databases open the door to
abusive tracking, enabling anyone with access to pry into the lives of his boss, his exwife, or his romantic, political, or workplace rivals.

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In July 2012, American Civil Liberties Union affiliates in 38 states and Washington, D.C.,
sent 587 public records act requests to local police departments and state agencies
to obtain information on how these agencies use license plate readers. We also filed
requests with the U.S. Departments of Justice, Homeland Security, and Transportation
to learn how the federal government has used grants to encourage the widespread
adoption of license plate readers, as well as how it is using the technology itself.
NUMBER OF POLICE DEPARTMENTS AND
STATE AGENCIES WE ASKED FOR RECORDS
587

NUMBER THAT HAVE NUMBER THAT HAVE
RESPONDED SO FAR NOT RESPONDED
293

294

We received over 26,000 pages of documents from the law enforcement agencies that
responded to our requests, about their policies, procedures, and practices for using
license plate readers.
This report provides an overview of what we have learned about license plate readers:
what their capabilities are, how they are being used, and why they raise privacy issues
of critical importance. We close by offering specific recommendations designed to allow
law enforcement agencies to use license plate readers for legitimate purposes without
subjecting Americans to the permanent recording of their every movement.
The potential privacy harms discussed in this report are not merely theoretical. In August
2012, the Minneapolis Star Tribune published a map displaying the location, obtained via
a public records request, of the 41 times that Mayor R.T. Rybak’s car had been recorded
by a license plate reader in the preceding year.1 The Star Tribune also reported that of the
805,000 plate scans made in June, less than one percent were hits.2 Yet for as long as the
information was retained, the other 99 percent of scans were also vulnerable to the risk
that they might be released, used by the police to track innocent people, or otherwise
abused. The alarming fact that a law-abiding citizen’s sensitive location history could be
revealed so easily was not lost on this exposed mayor. In response to the Star Tribune’s
reporting, he directed the city’s chief of police to recommend a new policy on data
retention.3 We hope the findings of our report spur similar policy changes.

1
Eric Roper, City Cameras Track Anyone, Even Minneapolis Mayor Rybak, Minneapolis Star Tribune (Aug. 17, 2012),
http://www.startribune.com/local/minneapolis/166494646.html.
2
Eric Roper, Police Cameras Quietly Capture License Plates, Collect Data, Minneapolis Star Tribune (Aug. 10, 2012),
http://www.startribune.com/local/minneapolis/165680946.html.
3
Id. Minnesota now has a temporary data classification that makes the plate data collected by readers exempt from disclosure
under the state public records laws. That temporary classification applies statewide and is set to expire August 1, 2015 absent
legislative action on the issue. Minnesota Department of Administration, Information and Analysis Division, Current Temporary
Classifications, http://www.ipad.state.mn.us/docs/tccurrent.html.

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THE TECHNOLOGY
Automatic license plate readers are made up of high-speed cameras designed to
capture a photograph of each and every passing license plate, combined with software
that analyzes those photographs to identify the license plate number.4 These systems
store extensive location information about each automobile.5
License plate reader cameras
can be placed almost anywhere,
from mobile vehicles like patrol
cars6 to fixed objects like bridges
and overpasses.7 There are even
apps that allow law enforcement
agents on foot to scan license
plates with their smartphones.8
On taking a photograph, license
plate reader systems quickly:
• Identify any license plates
within the photograph
• Convert each license plate
number into machinereadable text

4
ELSAG North America, Mobile Plate Hunter-900 Car Systems User Guide (June 2011), Documents Received in Response to ACLU
Public Records Requests, all of which are available at aclu.org [hereinafter “Public Records Responses”], p. 6422, http://www.aclu.
org/files/FilesPDFs/ALPR/vermont/alprpra_departmentofpublicsafety_VT%20(2).pdf; Motorola, Automatic License Plate Recognition
Solutions Brief (2011), Public Records Responses p.10717, http://www.aclu.org/files/FilesPDFs/ALPR/illinois/alprpra_burbankpd_
burbankil.PDF.
5
L-3 Mobile-Vision, AlertVU Mobile User Manual, Public Records Responses, p. 18733, http://www.aclu.org/files/FilesPDFs/ALPR/
new-jersey/18731-18763%20Woodbridge%20ALPR%20User%20Manual.pdf; Federal Signal, PAGIS ALPR Software Data Sheet (2010),
Public Records Responses, p. 18538, http://www.aclu.org/files/FilesPDFs/ALPR/new-jersey/18537-18538%20Vineland%20OPRA%20
Response%2024.pdf; Vigilant Video, Mobile License Plate Recognition Systems, Public Records Responses, p. 15935, http://www.aclu.
org/files/FilesPDFs/ALPR/new-york/alprpra_yonkerspolicedepartment_yonkersny_1.pdf.
6
Federal Signal, Slate ALPR Camera Data Sheet (2009), Public Records Responses, pp. 1866-87, http://www.aclu.org/files/
FilesPDFs/ALPR/texas/alprpra_AustinPD_AustinTX%20(56).pdf; ELSAG North America, How the MPH-900 Works, (Sept. 16, 2011),
Public Records Responses, p. 4334, http://www.aclu.org/files/FilesPDFs/ALPR/north-carolina/alprpra_wrightsvillebeachpd_
wrightsvillebeachnc%20(3).pdf.
7
Federal Signal, Spike+ Model P372 Data Sheet (2008), Public Records Responses, pp. 2425-26, http://www.aclu.org/files/
FilesPDFs/ALPR/texas/alprpra_grapevinePD_grapevineTX%20(5).pdf; ELSAG North America, Fixed Plate Hunter-900 (Sept. 16,
2011), Public Records Responses, p. 4330, http://www.aclu.org/files/FilesPDFs/ALPR/north-carolina/alprpra_wrightsvillebeachpd_
wrightsvillebeachnc%20(3).pdf%20; Prime Communications, Corporate Overview, Public Records Responses, p. 3555, http://www.aclu.
org/files/FilesPDFs/ALPR/texas/alprpra_texastechuniversity_lubbocktx%20(4).pdf.
8
Vigilant Video, CarDetector Mobile Companion, p. 1 (2012), http://vigilantsolutions.com/wp-content/uploads/2012/09/VigilantMobile-Companion-Datasheet-092012.pdf.

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• Check each license plate number against manually entered plate numbers and
“hot lists” of plates that have been uploaded to the system
• Provide an instant alert to a law enforcement agent when a match or hit appears
• Store the photograph, the license plate number, and the date, time, and location
where the automobile was seen9
Prices for license plate reader systems have decreased markedly in recent years and are
continuing to fall.10 State and federal grants can further lower the cost law enforcement
agencies must pay out of pocket to purchase license plate reading equipment.11 The cost
of storing data collected from license plate readers is also dropping. Between 2000 and
2010, the inflation-adjusted cost to purchase one gigabyte of hard drive storage fell from
about $10 to less than ten cents.12
As license plate readers become increasingly widespread, they are being put to a variety
of uses. Perhaps the most common law enforcement use of license plate readers is,
as described above, to check plates against “hot lists,” including the National Crime
Information Center vehicle file (which includes stolen vehicles and vehicles used in the
commission of a crime). Other common hot lists include the plate numbers of those who
are the subject of an AMBER Alert or felony arrest warrant, and people who have been
required to register as sex offenders or are on supervised release.13
Data collected from license plate readers can also be pooled in centralized databases.14
Software can then be used to plot all of the plate reads associated with a particular
vehicle to trace a person’s past movements.15 The systems can also plot all vehicles at

9
Federal Signal, PAGIS ALPR Software Data Sheet (2010), Public Records Responses, pp. 18537-38, http://www.aclu.org/
files/FilesPDFs/ALPR/new-jersey/18537-18538%20Vineland%20OPRA%20Response%2024.pdf; Vigilant Video, National Vehicle
Location Service, Public Records Responses, pp. 15939-41, http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_
yonkerspolicedepartment_yonkersny_1.pdf.
10
According to the Wall Street Journal, the price of a standard two-camera license plate recognition system has dropped from
$25,000 to $15,000 in just a few years. Julia Angwin & Jennifer Valentino-Devries, New Tracking Frontier: Your License Plates, Wall St.
J. (Sept. 29. 2012), http://online.wsj.com/article/SB10000872396390443995604578004723603576296.html. See also Homeland Security
News Wire, Reduced Prices for License Plates [sic] Readers Attracts More Buyers, (Jan. 24, 2012), http://www.homelandsecuritynewswire.
com/srlet20120124-reduced-prices-for-license-plates-readers-attracts-more-buyers (stating that the price of an ALPR system has
fallen from an initial cost of $24,000 to $17,000 as of January 2012).
11
ELSAG North America, Grant Guide, http://elsag.com/grant_guide.htm.
12
John Villasenor, Recording Everything: Digital Storage as an Enabler of Authoritarian Governments, Center For Technology
Innovation at Brookings, p. 4 (Dec. 14, 2011), http://www.brookings.edu/~/media/research/files/papers/2011/12/14%20digital%20
storage%20villasenor/1214_digital_storage_villasenor.pdf.
13
Federal Signal, PAGIS ALPR Software Data Sheet (2010), Public Records Responses, p. 18537, http://www.aclu.org/files/
FilesPDFs/ALPR/new-jersey/18537-18538%20Vineland%20OPRA%20Response%2024.pdf; High Point Police Department General Order
on Automated License Plate Readers (June 1, 2011), Public Records Responses, pp. 812-13, http://www.aclu.org/files/FilesPDFs/ALPR/
north-carolina/alprpra_HighPointPD_HighPointNC%20(3).pdf.
14
Motorola, Automatic License Plate Recognition Solutions Brief, p. 3 (2011), http://www.motorola.com/web/Business/_
Documents/Application%20Briefs/Motorola_ALPR_RO-14-2005B.pdf.
15
Id.; Prime Communications, Corporate Overview, Public Records Responses, p. 3557, http://www.aclu.org/files/FilesPDFs/ALPR/
texas/alprpra_texastechuniversity_lubbocktx%20(4).pdf.

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a particular location, such as the location where a crime — or a political protest — took
place.16
Additional uses for license plate readers are arising as the cameras become more
affordable and widespread.
VEHICLE VERIFICATION
Photographs captured by license plate readers may contain more than simply the
license plate, and sometimes include a substantial part of a vehicle, its occupants, and
its immediate vicinity.17 Law enforcement can use captured photographs to verify witness
descriptions of vehicles and confirm identifying features.18 Photographs of cars and
drivers can also be printed and distributed to the press and public.19
GEOFENCING
Law enforcement or private companies can construct a virtual fence around a
designated geographical area, to identify each vehicle entering that space.20
NON-LAW ENFORCEMENT
License plate readers can also be used for non-law enforcement purposes, such as
repossession of vehicles and parking enforcement.21

16
Prime Communications, Corporate Overview, Public Records Responses, p. 3557, http://www.aclu.org/files/FilesPDFs/ALPR/
texas/alprpra_texastechuniversity_lubbocktx%20(4).pdf; Maryland State Police, General Order on Automated License Plate Recognition
Program (May 2, 2012), Public Records Responses, p. 502, http://www.aclu.org/files/FilesPDFs/ALPR/maryland/alprpramspmd (2).pdf;
Miami-Dade Police, Technical Specifications for Mobile License Plate Readers, Public Records Responses, p. 6252, http://www.aclu.org/
files/FilesPDFs/ALPR/florida/alprpra_miamidadecountypd_miamicountyfl.pdf.
17
Photographs captured by license plate readers may contain more than simply the license plate. A large manufacturer, ELSAG
North America, advertises that its cameras “capture nearly twice the physical area — the sweet spot — and that means more
information for law enforcement.” The advertised “sweet spot” captures not only the car’s license plate, but “a significant portion of the
car and part of the car’s surroundings,” leaving room for the car’s driver, the vehicle’s passengers, or passing pedestrians to also be
captured by the camera. Thus, photographs of individuals are also being captured and stored. ELSAG North America, ALPR Products
and Solutions — Mobile Plate Hunter-900, http://www.elsag.com/mobile.htm; International Association of Chiefs of Police, Privacy
Impact Assessment Report for the Utilization of License Plate Readers, Public Records Responses, pp. 380-81, https://www.aclu.org/
files/FilesPDFs/ALPR/maryland/alprpra_MPIA_md.pdf; Prime Communications, Corporate Overview, Public Records Responses,
p. 3556, http://www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_texastechuniversity_lubbocktx%20(4).pdf; see generally Angwin &
Valentino-Devries, supra note 10.
18
Prime Communications, Corporate Overview, Public Records Responses, p. 3556, http://www.aclu.org/files/FilesPDFs/ALPR/
texas/alprpra_texastechuniversity_lubbocktx%20(4).pdf.
19
Id.
20
For example, Tiburon, California has license plate readers monitoring its only two roads that leave the town. Cyrus Favriar,
Rich California Town Considers License Plate Readers For Entire City Limits, Ars Technica (Mar. 5, 2013), http://arstechnica.com/
tech-policy/2013/03/rich-california-town-considers-license-plate-readers-for-entire-city-limits/. Prime Communications, Corporate
Overview, Public Records Responses, p. 3557, http://www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_texastechuniversity_
lubbocktx%20(4).pdf; ELSAG North America, Geofencing Capabilities of the Mobile Plate Hunter-900, p. 1 (Sept. 14, 2011), http://elsag.
com/media/content/ELSAG_geofencing-ss(1).pdf.
21
Texas Tech University Parking Service, Parking in the Buff: Parking in a Post-Permit World (Apr. 24, 2012), Public Records
Responses, p. 3496-3546, http://www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_texastechuniversity_lubbocktx (2).pdf; Vigilant
Video, National Vehicle Location Services Information Sheet, Public Records Responses, p. 15921, http://www.aclu.org/files/FilesPDFs/
ALPR/new-york/alprpra_yonkerspolicedepartment_yonkersny_1.pdf; Prime Communications, Corporate Overview, Public Records
Responses, p. 3555, http://www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_texastechuniversity_lubbocktx%20(4).pdf; Michael
Harlow, License Plate Recognition: It’s Grown Far Beyond Airports, Parking Today (July 2009), http://www.parkingtoday.com/articledetails.
php?id=788; Martha Groves, Servant or Snoop in the Parking Garage?, L.A. Times (Jan. 23, 2011), http://articles.latimes.com/2011/jan/23/
local/la-me-santa-monica-parking-20110123; Angwin & Valentino-Devries, supra note 10; Digital Recognition Network, http://www.
drndata.com/index.html.

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LICENSE PLATE READERS POSE
PRIVACY RISKS
Tens of thousands of license plate readers are now deployed throughout the United
States. Unfortunately, license plate readers are typically programmed to retain the
location information and photograph of every vehicle that crosses their path, not simply
those that generate a hit.22 The photographs and all other associated information are
then retained in a database, and can be shared with others, such as law enforcement
agencies, fusion centers, and private companies.23 Together these databases contain
hundreds of millions of data points revealing the travel histories of millions of motorists
who have committed no crime.
Longer retention periods and more widespread sharing allow law enforcement agents
to assemble the individual puzzle pieces of where we have been over time into a single,
high-resolution image of our lives. This constant monitoring and permanent recording
violates our privacy in a number of respects.

Chilling effects
In many places in America, license plate readers were initially deployed relatively
sparsely, for example, at the entry and exit points of various towns.24 But as license plate
readers have proliferated, they no longer capture individuals’ movements at only a few
points. Increasingly, they are capturing drivers’ locations outside church, the doctor’s
office, and school, giving law enforcement and private companies that run the largest
databases the ability to build detailed pictures of our lives.
Location data can reveal extremely sensitive information about who we are and what we
22
ELSAG North America, Car System User’s Guide (June 2011), Public Records Responses, p. 6422-23, http://www.aclu.org/files/
FilesPDFs/ALPR/vermont/alprpra_departmentofpublicsafety_VT(2).pdf; L-3 Mobile-Vision, AlertVU Mobile User Manual, Public Records
Responses, p. 18733, http://www.aclu.org/files/FilesPDFs/ALPR/new-jersey/18731-18763%20Woodbridge%20ALPR%20User%20
Manual.pdf.
23
Motorola Solutions Brief, supra note 4. See also Commerce City, Grant Application to Colorado Automobile Theft Prevention
Authority Grant Program (Feb. 1, 2012), Public Records Responses, p. 7881, http://www.aclu.org/files/FilesPDFs/ALPR/colorado/
alprpra_commercecitypd_commercecityca (5).pdf (police departments sharing license plate data with each other); Memorandum of
Understanding between National Capital Region’s License Plate Reader Information Sharing Program and Rockville Police (Mar. 29,
2012), Public Records Responses, pp. 393-99, https://www.aclu.org/files/FilesPDFs/ALPR/maryland/alprpra_MPIA_md.pdf (police
department sharing license plate data with a regional fusion center); Vigilant Solutions, Car Detector Mobile ALPR/ANPR (2012), Public
Records Responses, p. 15918, http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_yonkerspolicedepartment_yonkersny_1.pdf
(police departments sharing data with a private company).
24
Tiburon, California takes this approach, and retains data for 30 days. Cyrus Farivar, Your Car, Tracked: The Rapid Rise of License
Plate Readers, Ars Technica (Sept. 27, 2012), http://arstechnica.com/tech-policy/2012/09/your-car-tracked-the-rapid-rise-of-licenseplate-readers/.

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do. As the U.S. Court of Appeals for the D.C. Circuit explained in a recent GPS tracking
case:
A person who knows all of another’s travels can deduce whether he is a
weekly church goer, a heavy drinker, a regular at the gym, an unfaithful
husband, an outpatient receiving medical treatment, an associate of
particular individuals or political groups — and not just one such fact
about a person, but all such facts.25
And license plate readers can be used for tracking people’s movements for months
or years on end, chilling the exercise of our cherished rights to free speech and
association.
While police departments and government agencies argue that the data they collect will
be used only for proper purposes, even the International Association of Chiefs of Police
has recognized that pervasive surveillance can have negative chilling effects regardless
of its purpose. As it has explained, “The risk is that individuals will become more
cautious in the exercise of their protected rights of expression, protest, association, and
political participation because they consider themselves under constant surveillance.”26
Psychologists have confirmed through multiple studies that people do in fact alter
their behavior when they know they are being watched.27 In one such study, the mere
presence of a poster of staring human eyes was enough to significantly change the
participants’ behavior.28

Abusive tracking
When police departments lack policies limiting access to license plate data and
monitoring its use, abuse of the technology can occur. Other location tracking
technologies, such as attachment of GPS devices to vehicles and tracking people

25
United States v. Maynard, 615 F.3d 544, 562 (D.C. Cir. 2010).
26
International Association of Chiefs of Police, Privacy Impact Assessment Report for the Utilization of License Plate Readers, p. 13
(2009), http://www.theiacp.org/LinkClick.aspx?fileticket=N%2BE2wvY%2F1QU%3D&tabid=87.
27
See Jay Stanley, Does Surveillance Affect Us Even When We Can’t Confirm We’re Being Watched? Lessons From Behind the Iron
Curtain, Free Future (Oct. 15, 2012), http://www.aclu.org/blog/national-security/does-surveillance-affect-us-even-when-we-cantconfirm-were-being-watched.
28
Sander van der Linden, How the Illusion of Being Observed Can Make You a Better Person, Sci. Am. (May 3, 2011), http://www.
scientificamerican.com/article.cfm?id=how-the-illusion-of-being-observed-can-make-you-better-person; M. Ryan Calo, People Can Be
So Fake: A New Dimension to Privacy and Technology Scholarship, 114 Penn St. L. Rev. p. 809 (2010), http://www.pennstatelawreview.org/
articles/114/114%20Penn%20St.%20L.%20Rev.%20809.pdf.

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through their cell phones, are now regularly utilized to facilitate stalking.29 There is no
reason to believe that license plate readers will prove an exception.
License plate reader systems allow law enforcement agents to enter license plate
numbers manually and then receive automated alerts on those plates in the same way
they would any plate listed in an approved hot list. This method enables misuse: Anyone
with access to these systems could track his boss, his ex-wife, his romantic or workplace
rivals, friends, enemies, neighbors, family, and so forth. An agent could target the owners
of vehicles parked at political meetings, gay bars, gun stores, or abortion clinics.

Institutional abuse
In addition to abuse by individual law enforcement agents, license plate readers can be
subject to larger-scale institutional abuse as a matter of policy. For decades of the 20th
century, the FBI and other federal agencies illegally targeted activists in the civil rights,
anti-war, and labor movements. Today, law enforcement agencies are again carrying out
systematic surveillance of peaceful political protesters.30 And in other countries, political
protesters have already been subjected to surveillance through license plate reader
systems. In the United Kingdom, John Catt, a retiree and anti-war protester, was pulled
over by an anti-terror unit based on a license plate reader hit.31 The BBC reports that his
license plate was put on a hot list after an anti-war protest.32

Discriminatory targeting
License plate reader systems can also facilitate discriminatory targeting. An agent
who manually enters plates into a license plate reader system based on discriminatory
rationales could check far more plates than he could without the technology. Also,
discrimination can exist in deciding where to place the cameras. Whole communities
may be targeted based on their religious, ethnic, or associational makeup. In the
U.K., law enforcement agents installed over 200 cameras and license plate readers

29
Katrina Baum et al., Bureau of Justice Statistics: Stalking Victimization in the United States, at 5 (Jan. 2009) (“Global positioning
system (GPS) technology comprised about a tenth of the electronic monitoring of stalking victims.”), http://www.ovw.usdoj.gov/docs/
stalking-victimization.pdf; Justin Scheck, Stalkers Exploit Cellphone GPS, Wall St. J., Aug. 4, 2010, http://online.wsj.com/article/SB10001
424052748703467304575383522318244234.html.
30
See ACLU, Spyfiles, www.aclu.org/spyfiles.
31
Richard Bilton, Camera Grid to Log License Plates, BBC (May 22, 2009), http://news.bbc.co.uk/2/hi/programmes/whos_watching_
you/8064333.stm.
32
Id.

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PERVASIVE, PERMANENT MONITORING
If regulations are not put in place to limit the use of license plate readers,
there is a risk that they will be abused through scenarios such as these:

A citizen group organizes a protest calling for an end to the
“war on terror.” Many people show up. The police department
uses a license plate reader-equipped police cruiser to scan
the license plates of all who park in a nearby parking lot to
attend the protest. They then investigate these individuals,
showing up at their places of employment to ask questions
about their backgrounds.
A journalist at a small newspaper publishes a series
of explosive stories charging local police officers with
planting drugs on suspects in order to meet arrest
quotas. The stories are clearly based on insider
information, so police officials park a license plate reader
outside the newspaper’s office and check each car that
drives by against a list of police officers’ license plate
numbers. When they see an officer paying visits to the
newspaper, they fire him on a technicality.
The mayor of a medium-sized Midwest city is attempting to fight
off the first major challenge to his position in over 20 years, and
hears a rumor that his challenger has a mistress. He asks his police
commissioner to analyze historical license plate reader data for his
challenger’s license plate, and is able to confirm that he regularly
visits the home of a young, single woman after 10 p.m. The mayor
anonymously tips off a local journalist, who confirms the affair and
publishes a front-page story exposing it.

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in predominantly Muslim suburbs of Birmingham.33 Public outrage was such that the
agents dismantled the cameras, stating that cultivating the trust of the community was
the more effective approach.34 In New York City, police officers have reportedly driven
unmarked vehicles equipped with license plate readers around local mosques in order to
record each attendee.35 Police departments in other parts of the country could easily do
the same thing to Tea Party groups, anti-abortion protesters, or the political opposition
of a sheriff running for re-election.

33
Paul Lewis, CCTV Aimed at Muslim Areas in Birmingham to be Dismantled, The Guardian (Oct. 25, 2010), http://www.guardian.co.uk/
uk/2010/oct/25/birmingham-cctv-muslim-areas-surveillance.
34
Id.
35
Adam Goldman & Matt Apuzzo, With Cameras, Informants, NYPD Eyed Mosques, Associated Press (Feb. 23, 2012), http://www.
ap.org/Content/AP-In-The-News/2012/Newark-mayor-seeks-probe-of-NYPD-Muslim-spying.

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LICENSE PLATE READERS ARE
WIDELY USED BY STATE AND LOCAL
LAW ENFORCEMENT AGENCIES
License plate readers are already a common tool in the arsenals of many local police
departments. In a 2011 survey, almost three-quarters of police agencies included in the
survey reported using license plate readers — and a full 85 percent of agencies planned
on increasing their use of license plate readers over the next five years.36 Even more
strikingly, the same report found that although police departments today typically only
have license plate readers installed on a few vehicles, in five years these departments
anticipate that, on average, plate readers will be installed on 25 percent of all patrol
cars.37 One major license plate reader manufacturer, ELSAG, states that its machines
are operating in close to 1,200 agencies in all 50 states38 and more than 5,000 agencies
worldwide.39 Another manufacturer, PIPS Technology, claims that it has deployed 20,000
machines to agencies worldwide.40
Not only are license plate readers widely deployed, but few police departments place
any substantial restrictions on how automatic license plate readers can be used. The
approach of the Pittsburg Police Department in California is typical: It states that license
plate readers can be used for “any routine patrol operation or criminal investigation.”41
It makes clear that “[r]easonable suspicion or probable cause is not required.”42 While
many police departments do prohibit police officers from using license plate readers for

36
Police Executive Research Forum, How Are Innovations in Technologies Transforming Policing?, p. 31 (Jan. 2012), http://
policeforum.org/library/critical-issues-in-policing-series/Technology_web2.pdf.
37
Id. at p. iii.
38
Press Release, ELSAG North America, IACP 2011: ELSAG Unveils the Latest License Plate Recognition Tech. (Oct. 21, 2011),
http://www.policeone.com/police-products/traffic-enforcement/license-plate-readers/press-releases/4538797-IACP-2011-ELSAGUnveils-the-Latest-License-Plate-Recognition-Technology/; ELSAG North America, MPH-900 Deployments, http://www.elsag.com/
deployment.htm.
39
ELSAG North America, References, http://www.elsag.com/references.htm.
40
Press Release, PIPS Technology, PIPS Technology, Inc. Announces Handheld OCR (Oct. 21, 2011), http://www.federalsignal.com/
pdf/pressrelease/2011_10-21_PIPS_Handheld_final.pdf.
41
Pittsburg Police Department, Policy on Automated License Plate Readers (Mar. 22, 2012), Public Records Responses, p. 94,
http://www.aclu.org/files/FilesPDFs/ALPR/california/alprpra_pittsburgpd_pittsburgca.pdf.
42
Id. The Milpitas, California Police Department states that the use of the department’s ALPR technology is for “law enforcement
investigations only.” Letter from Milpitas Police Department to ACLU of Northern California (Aug. 8, 2012), Public Records Responses,
p. 128, http://www.aclu.org/files/FilesPDFs/ALPR/california/alprpra_milpitaspd_milpitasca.pdf. Rockville, Maryland’s license plate
reader policy states the technology may be used for “Homeland Security applications, electronic surveillance, suspect interdiction,
stolen property recovery and a number of other policing objectives.” Rockville Police Department, General Order on License Plate
Reader Systems (Apr. 30, 2012), Public Records Responses, p. 363, https://www.aclu.org/files/FilesPDFs/ALPR/maryland/alprpra_
MPIA_md.pdf. The Maryland Coordination and Analysis Center, which runs a state-based regional license plate sharing center, allows
participating agencies to access plate data whenever it is “related to a criminal investigation or relevant to the safety of officers and
citizens.” Maryland Coordination and Analysis Center, License Plate Recognition Intelligence Bulletin (Jan. 31, 2011), Public Records
Responses, p.432, http://www.aclu.org/files/FilesPDFs/ALPR/maryland/alprpra_dnr_md%20(1).pdf.

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(T)he use of license
plate readers “is only
limited by the officer’s
imagination.”
— Scarsdale, NY Police Department

their own personal uses (tracking friends
and loved ones, for example), these are
the only restrictions. As the Scarsdale
Police Department in New York puts it,
the use of license plate readers “is only
limited by the officer’s imagination.”43

License plate readers collect vast quantities of data on
innocent people
While it is legitimate to use license plate readers to identify those who are alleged to
have committed crimes, the overwhelming majority of people whose movements are
monitored and recorded by these machines are innocent, and there is no reason for the
police to be keeping records on their movements. Ordinary people going about their daily
lives have every right to expect that their movements will not be logged into massive
government databases.
The vast majority of license plate data are collected from people who have done nothing
wrong at all. Often, only a fraction of 1 percent of reads are hits — and an even smaller
fraction result in an arrest.
In our records requests, documents from Maryland illustrate this point. Approximately
three-quarters of Maryland’s law enforcement agencies are networked into Maryland’s
state data fusion center, which collected more than 85 million license plate records in
2012 alone.44 According to statistics compiled by the fusion center for that year to date
through May: 45
• Maryland’s system of license plate readers had over 29 million reads. Only 0.2
percent of those license plates, or about 1 in 500, were hits. That is, only 0.2
percent of reads were associated with any crime, wrongdoing, minor registration
problem, or even suspicion of a problem.
• Of the 0.2 percent that were hits, 97 percent were for a suspended or revoked
registration or a violation of Maryland’s Vehicle Emissions Inspection Program.

43
Scarsdale Police Department, General Order on ELSAG Automatic License Plate Readers (Sept. 1, 2008), Public Records
Responses, p. 12638, http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_scarsdalepolicedepartment_scarsdaleny_1.pdf.
44
Governor’s Office of Homeland Security, Intelligence/Information Sharing (Dec. 2012), http://www.gohs.maryland.gov/ii_sharing_
accomplishments.html.
45
Maryland Coordination and Analysis Center, Networked Mobile License Plate Reader Alerts (May 2012), Public Records
Responses, p. 440, http://www.aclu.org/files/FilesPDFs/ALPR/maryland/alprpra_msp_md%20(1).pdf.

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While these vehicles perhaps should not be on the road, they are not the dangers
to society that law enforcement agencies routinely describe when justifying their
use of license plate readers.
For every one million plates read in Maryland, only 47 were potentially associated with
more serious crimes—a stolen vehicle or license plate, a wanted person, a violent
gang or terrorist organization, a sex offender, or Maryland’s warrant-flagging program.
Furthermore, even these 47 alerts may not have helped the police catch criminals or

ONE MILLION
PLATES READ

2,000

47

HITS

SERIOUS

CRIMES

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prevent crimes. While people on the violent gang, terrorist, and sex offender lists are
under general suspicion, they are not necessarily wanted for any present wrongdoing.46
In short, Maryland’s license plate readers collect massive amounts of data, almost
none of which are tied to any known or even suspected wrongdoing. Even the vast
majority of hits are for minor regulatory violations.
While Maryland provided us with the clearest data on this practice, we found similar
patterns across the country:

COLLECTION PERIOD

PLATE READS STORED

HIT
RATE

Burbank, IL i

August 2011– July 2012

706,918

0.3%

Rhinebeck, NY ii

January– March 2012

99,771

0.01%

High Point, NC iii

August 2011– June 2012

70,289

0.08%

TOWN/CITY

i.
Burbank Police Department, Reads Statistics (July 31, 2012), Public Records Responses, pp. 10886-902, http://www.aclu.org/
files/FilesPDFs/ALPR/illinois/alprpra_burbankpd_burbankil.PDF.
ii.
Rhinebeck Police Department, Quarterly License Plate Reader Progress Reports (2011 & 2012), Public Records Responses,
p.12621-22, http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_rhinebackpolicedepartment_rhinebackny_1.pdf. Seven
suspended licenses, thirteen suspended registrations, five uninsured motor vehicles, and one unlicensed operator. Id.
iii.
High Point Police Department, Reads Statistics (Aug. 13, 2012), Public Records Responses, pp. 801-10, http://www.aclu.org/
files/FilesPDFs/ALPR/north-carolina/alprpra_HighPointPD_HighPointNC%20(3).pdf.

The above information reflects the hit rate, which is the best evidence of efficacy
most agencies provided but is imperfect because hits are not always accurate or even
generated based upon the suspicion that someone is violating the law. A more helpful
statistic is provided by the Minnesota State Patrol. Of the 1,691,031 plates scanned
between 2009-2011, just 852 citations were issued and 131 arrests were made. 47 That
is 0.05 percent of plate reads.
Again, there is no problem with the use of license plate readers to identify individuals
suspected of violating the law. But the above data provide a striking illustration of the
wide dragnet that license plate readers often cast. Because they snap pictures of every
passing vehicle, they generate millions of data points on the movements of individuals
whom no one suspects of violating any law.
46
According to government training materials, placement on its “violent gang or terrorist” list is “based on investigative
information not previously subject to independent judicial review,” and indicates that someone is of interest, not that they are
wanted for a crime. Violent Gang and Terrorist Organization File, Operator’s Lesson Plan (Feb. 2005), http://www.in.gov/isp/files/
Violent_Gang_Terrorist_Organization_File.pdf
47
Minnesota State Patrol, License Plate Reader Data Totals, Public Records Responses, p. 753, http://www.aclu.org/files/
FilesPDFs/ALPR/minnesota/alprpra_minnesotastatepatrol_stpaulmn_1%20(6).pdf.

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Many agencies retain data on innocent
Americans for long periods of time
There is no reason for law enforcement agencies to retain data on the comings and
goings of innocent Americans. While holding onto “hit” data while an investigation or
case is ongoing is legitimate, law enforcement agencies should not be storing data about
people who have done nothing wrong.
Some law enforcement agencies delete non-hit data rapidly, proving that such privacyprotective practices are workable:
• The Ohio State Highway Patrol’s license plate reader policy states that “all
‘non-hit’ [license plate reader] captures shall be deleted immediately.” It further
specifies that license plate reader “captures shall not be collected, stored, or
shared with the intent of data mining.”48
• The Minnesota State Patrol keeps license plate data for 48 hours before deleting
it, keeping data longer only when there are “extenuating circumstances.”49
Some other police departments, while not as quick to delete as the departments above,
also keep data for relatively short periods of time:
• Brookline, Mass., retains data for 14 days.50
• Police in Tiburon, Calif., delete all license plate reader data after 30 days or less.51
Deleting data quickly prevents license plate reader systems from compiling huge
storehouses of our location information. The Minnesota State Patrol, for example, scans
tens of thousands of license plates per month — a total of almost 1.7 million plates over
three years.52 However, in the absence of “extenuating circumstances,” the agency has

48
Ohio State Highway Patrol, Policy on Mobile and Stationary License Plate Recognition (Dec. 23, 2008), Public Records Responses,
p. 14851, http://www.aclu.org/files/FilesPDFs/ALPR/ohio/14749-14851%20Department%20of%20Public%20Safety.pdf.
49
Minnesota State Patrol, General Order on License Plate Readers (Sept. 28, 2009), Public Records Responses, p. 730, http://
www.aclu.org/files/FilesPDFs/ALPR/minnesota/alprpra_minnesotastatepatrol_stpaulmn_1%20(3).pdf; Email from Minnesota State
Patrol to ACLU of Minnesota (Aug. 9, 2012), Public Records Responses, p. 733, http://www.aclu.org/files/FilesPDFs/ALPR/minnesota/
alprpra_minnesotastatepatrol_stpaulmn_1%20(4).pdf.
50
Shawn Musgrave, License Plate-Reading Devices Fuel Privacy Debate, Boston Globe (Apr. 9, 2013), http://www.
bostonglobe.com/metro/2013/04/08/big-brother-better-police-work-new-technology-automatically-runs-license-plateseveryone/1qoAoFfgp31UnXZT2CsFSK/story.html
51
Tiburon Town Council Minutes (Mar. 4, 2009), Public Records Responses, p. 7201, http://www.aclu.org/files/FilesPDFs/ALPR/
california/alprpra_tiburonpd_tiburonca%20(1).pdf; Tiburon Town Council Minutes (Nov. 18, 2009), Public Records Responses, pp.
7234-35, http://www.aclu.org/files/FilesPDFs/ALPR/california/alprpra_tiburonpd_tiburonca%20(1).pdf.
52
Minnesota State Patrol, License Plate Reader Data Totals, Public Records Responses, pp. 750-53, http://www.aclu.org/files/
FilesPDFs/ALPR/minnesota/alprpra_minnesotastatepatrol_stpaulmn_1%20(7).pdf.

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Retention policies: All over the map
MILPITAS, CA

MINNESOTA STATE PATROL

Population: 67,000
Data policy: None
Stored plate reads: 4.7 million

Population: 5.3 million
Data policy: Delete after 48 hours
Stored plate reads: Less than 20,000

(as of 8/2/12)

GRAPEVINE, TX

JERSEY CITY, NJ

Population: 47,000
Data policy: None
Stored plate reads: 2 million

Population: 250,000
Data policy: Delete after 5 years
Stored plate reads: 10 million (estimated)

(as of 8/29/12)

(as of 8/2/12)

a policy of deleting all license plate data 48 hours after it is collected.53 As a result,
the amount of data in the agency’s possession, according to a document we obtained,
“depends on the day.”54 Given that records show the daily number of plate scans rarely
53
Minnesota State Patrol, General Order on License Plate Readers (Sept. 28, 2009), Public Records Responses, p. 730, http://
www.aclu.org/files/FilesPDFs/ALPR/minnesota/alprpra_minnesotastatepatrol_stpaulmn_1%20(3).pdf.
54
Email from Minnesota State Patrol to ACLU of Minnesota (Aug. 9, 2012), Public Records Responses, p. 733, http://www.aclu.
org/files/FilesPDFs/ALPR/minnesota/alprpra_minnesotastatepatrol_stpaulmn_1%20(4).pdf.

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exceeds 10,000, it is unlikely that the number of records would be more than 20,000 in a
48-hour period.55
In the absence of tight retention time limits, police departments rapidly accumulate vast
stores of location tracking data — again, nearly all of it on innocent people. For example:
• The Piedmont Police Department in California produced records showing that it
had accumulated 1,641,841 scanned records in the time period between August
2011 and August 2012. These records were still in storage as of Aug. 8, 2012.56
• In September 2012, Grapevine, Texas (a city in the Dallas-Fort Worth metropolitan
area) reported scanning on average 14,547 plates a day and had nearly 2 million
plates in its database.57
• Jersey City, N.J., collected 2.1 million plate reads in 2012.58 Because a New
Jersey attorney general directive compels all law enforcement agencies in the
state to ensure that license plate reader data is retained for five years, assuming
that 2012 is representative, it is likely that there are approximately 10 million
plate reads stored at any given time.59
See page 20 for a selection of the retention policies we have obtained, demonstrating the
range of existing data retention periods around the country.

All the pieces are lining up for widespread
sharing of license plate reader data
The mass collection and retention of plate data about innocent Americans is alarming in
and of itself, but it is all the more worrying because these data are increasingly being fed
into larger regional databases. These databases can be in the possession and control of
other government jurisdictions. Once a law enforcement agency shares data, it can lose
any say about how these data are used, stored, and shared.

55
Minnesota State Patrol, License Plate Reader Data Totals, Public Records Responses, pp. 750-53, http://www.aclu.org/files/
FilesPDFs/ALPR/minnesota/alprpra_minnesotastatepatrol_stpaulmn_1%20(7).pdf.
56
PRA Response letter from Piedmont PD (Aug. 9, 2012), Public Records Responses, pp. 22341-43, http://www.aclu.org/files/
FilesPDFs/ALPR/california/22341-22396 Piedmont PD ALPR Response (1901-56).pdf.
57
Letter from Grapevine Police Department to ACLU of Texas (Sept. 10, 2012), Public Records Responses, p. 2424, http://www.aclu.
org/files/FilesPDFs/ALPR/texas/alprpra_grapevinePD_grapevineTX(6).pdf.
58
Jersey City, Reads Statistics, Public Records Responses, p. 17584, https://www.aclu.org/files/FilesPDFs/ALPR/newjersey/17569-17584 Jersey City Supp OPRA Response 2 of 8.pdf.
59
New Jersey Attorney General, Guidelines for the Use of Automated License Plate Readers and Data (Dec. 3, 2010), Public Records
Responses, p. 6144, http://www.aclu.org/files/FilesPDFs/ALPR/new-jersey/alprpra_divisionofcriminaljustice_trentonnj_1%20(6).pdf.

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That said, today many law enforcement agencies share license plate reader data on
a case-by-case basis in response to specific requests from other law enforcement
agencies (and a few report no sharing).60 Requiring a case-by-case demonstration of
need is preferable to wholesale sharing because it ensures that data about innocent
people isn’t needlessly spread to additional government computer systems, a step that
increases the risk of its being misused or wrongfully disclosed.
However, there are already examples of license plate reader data being systematically
pooled into large regional databases:
• Greenbelt, Md., feeds plate information into the state fusion center, the
Maryland Coordination and Analysis Center (MCAC),61 and also participates in
a regional database called the National Capital Region LPR Project (NCR),62
which collects plate information from police departments in Washington,
D.C., Virginia, and Maryland.63 Although Greenbelt’s policy is to purge data
from its local hard drive after 30 days,64 its sharing practices undercut that
policy. MCAC stores all license plate data for one year, no matter what the
Text continues on p. 22.
60
For example, Grapevine, Texas, Jacksonville, North Carolina, and Mesquite, Texas do not allow third parties to access their
license plate data, while Hutchinson, Kansas and the Minnesota State Patrol only share data when a specific request is made. The
City of El Paso, Texas shares license plate reader data for “legitimate law enforcement purposes.” Newark, Delaware complies with
requests from other law enforcement agencies for specific license plate reads “related to criminal or traffic investigations.” Lincoln,
Nebraska shares license plate reader data only in response to an inquiry made by a prosecutor or defense attorney in an active
criminal case. Letter from Grapevine Police Department to ACLU of Texas (Sept. 10, 2012), Public Records Responses, p. 2424, http://
www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_grapevinePD_grapevineTX(6).pdf; Letter from Jacksonville Police Department
to ACLU of North Carolina (Aug. 21, 2012), Public Records Responses, p. 1481, http://www.aclu.org/files/FilesPDFs/ALPR/northcarolina/alprpra_jacksonvillepd_jacksonvillenc.pdf; Mesquite Police Department, Response to ACLU of Texas Records Request,
Public Records Responses, p. 10466, http://www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_mesquitepd_mesquitetx%20(2).
pdf; Email from Hutchinson Police Department to ACLU of Kansas and Western Missouri (Aug. 3, 2012), Public Records Responses,
p. 342, http://www.aclu.org/files/FilesPDFs/ALPR/kansas/alprpra_hutchinsonpd_hutchinsonka.pdf; Email from Minnesota State
Patrol to ACLU of Minnesota (Aug. 9, 2012), Public Records Responses, p. 733, http://www.aclu.org/files/FilesPDFs/ALPR/minnesota/
alprpra_minnesotastatepatrol_stpaulmn_1%20(4).pdf; City of El Paso, License Plate Reader Policy and Guidelines, Public Records
Responses, p. 10078, http://www.aclu.org/files/FilesPDFs/ALPR//texas/alprpra_elpasoPD_elpasotx%20(5).pdf; Letter from Newark
City Solicitor to ACLU of Delaware (Oct. 1, 2012), Public Records Responses, p. 7559, https://www.aclu.org/files/FilesPDFs/ALPR/
delaware/7558-7559 City of Newark FOIA Response.pdf; Letter from Lincoln Police Department to ACLU of Nebraska (Sept. 7,
2012), Public Records Responses, p. 4683, http://www.aclu.org/files/FilesPDFs/ALPR/nebraska/alprpra_lincolnpolicedepartment_
lincolnne_1.pdf.
61
Letter from Maryland Governor’s Office of Crime Control & Prevention to Greenbelt Police Department (Mar. 21, 2011), Public
Records Responses, p. 27406, https://www.aclu.org/national-security-technology-and-liberty/response-public-records-request7-greenbelt-police; Maryland’s LPR Program and Policy Overview: How We Differ from Most Agencies and Why (2011), http://www.
theiacp.org/Portals/0/pdfs/LEIM/2011Presentations/Maryland%27s-LPR-Program-and-Policy-Overview.pdf. Approximately three
quarters of Maryland’s law enforcement agencies are networked into MCAC, and the fusion center collected more than 85 million
license plate records in 2012 alone. Governor’s Office of Homeland Security, Intelligence/Information Sharing (Dec. 2012), http://
www.gohs.maryland.gov/ii_sharing_accomplishments.html.
62
Addendum to 2008 Grant Agreement for ALPR Equipment between Arlington County, Virginia and City of Greenbelt, Maryland
(Mar. 28, 2012), Public Records Responses, pp. 27378-81, https://www.aclu.org/national-security-technology-and-liberty/responsepublic-records-request-6-greenbelt-police; Memorandum of Understanding between National Capital Region’s License Plate Reader
Information Sharing Program and Greenbelt Police (Mar. 28, 2012), Public Records Responses, pp. 27384-90, https://www.aclu.org/
national-security-technology-and-liberty/response-public-records-request-6-greenbelt-police.
63
Prince William County Government, Motion to Approve MOU for the National Capital Region’s License Plate Reader
Information Sharing Program (July 17, 2012), http://eservice.pwcgov.org/documents/bocs/agendas/2012/0717/4-h.pdf.
64
City of Greenbelt, Response to ACLU of Maryland Records Request (Sept. 5, 2012), Public Records Responses, pp. 27367-68,
https://www.aclu.org/national-security-technology-and-liberty/response-public-records-request-6-greenbelt-police.

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Automatic license plate reader retention periods around
the country
JURISDICTION

PLATE DATA RETENTION PERIOD
1 to 30 days

Minnesota State Patrol

31 days to 1 yr

1 to 5 years

Indefinite

48 hours i

Burbank, IL

21 days ii

Deerpark, NY

30 days iii

Jacksonville, NC

30 days iv

Schenectady, NY

35 days v

New Paltz, NY

50 days vi

Boston, MA

90 days vii

Fishkill, NY

90 days viii

Franklin County, OH

90 days ix

Sugar Land, TX

90 days x

Raleigh, NC

6 months xi

New Castle County, DE

360 days xii

Dutchess County, NY

1 year xiii

High Point, NC

1 year xiv

Highland Village, TX

1 year xv

Charlotte-Mecklenburg, NC

18 months xvi

Aurora, CO

2 years xvii

Commerce City, CO

2 years xviii

Los Angeles County, CA

2 years xix

Plano, TX

2 years xx

Delaware Dept of Homeland Security

5 years xxi

New Jersey

5 years xxii

Grapevine, TX

Presumed indefinite

Mesquite, TX

Indefinite retention xxiv

Yonkers, NY

Indefinite retention xxv

xxiii

NOTE: Retention periods generally refer to non-hit data that has not been flagged as part of an investigation or incident.
Exact policies vary but usually cover the vast majority of automatic license plate reader reads.

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i.	
Minnesota State Patrol, General Order on License Plate Readers (Sept. 28, 2009), Public Records Responses, p. 730, http://
www.aclu.org/files/FilesPDFs/ALPR/minnesota/alprpra_minnesotastatepatrol_stpaulmn_1%20(3).pdf.
ii.	
Burbank Police Department, General Order on Automated License Plate Recognition Systems (Nov. 1, 2011), Public Records
Responses, p. 10702, http://www.aclu.org/files/FilesPDFs/ALPR/illinois/alprpra_burbankpd_burbankil.PDF.
iii.	
Deerpark Police Department, Special Order on License Plate Readers (Dec. 10, 2010), Public Records Responses, p. 12171,
http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_townofdeerparkpolicedepartment_deerparkny_1.pdf.
iv.	
Letter from Jacksonville Police Department to ACLU of North Carolina (Aug. 21, 2012), Public Records Responses, p. 1480,
http://www.aclu.org/files/FilesPDFs/ALPR/north-carolina/alprpra_jacksonvillepd_jacksonvillenc.pdf.
v.	
Schenectady Police Department, Response to New York Civil Liberties Union Records Request (Oct. 31, 2012), Public
Records Responses, p. 15558, http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_schenectadypolicedepartment_
schnectadyny_1.PDF.
vi.	
Letter from New Paltz Police Department to New York Civil Liberties Union (Aug. 8, 2012), Public Records Responses, p.
12393, http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_newpaltzpolicedepartment_newpaltzny_1.pdf.
vii.	 Boston Police, Special Order on License Plate Recognition System (Sept. 14, 2011), Public Records Responses, p. 4793,
http://www.aclu.org/files/FilesPDFs/ALPR/massachusetts/4790-4793 Boston_Special Order 11_026.pdf.
viii.	 Letter from Fishkill Police Department to New York Civil Liberties Union (Sept. 17, 2012), Public Records Responses, p.
12225, http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_fishskillpolicedepartment_fishskillny_1.pdf.
ix.	
Revised Memorandum of Understanding between Franklin County Sheriff’s Office and Agency Police Department
Outside Region #4, Public Records Responses, p. 14856, http://www.aclu.org/files/FilesPDFs/ALPR/ohio/14852%20-14894%20
Franklin%20County.pdf.
x.	
Sugar Land Police Department, General Order on Use of LPR Technology (Aug. 26, 2011), Public Records Responses, p.
14595, http://www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_sugarlandpd_sugarlandtx%20(2).pdf.
xi.	
Raleigh Police Department, Directive on Automated License Plate Recognition and Internet Protocol Camera System
(Sept. 5, 2012), Public Records Responses, p. 4033, http://www.aclu.org/files/FilesPDFs/ALPR/north-carolina/alprpra_raleighpd_
raleighnc.pdf.
xii.	 Letter from New Castle County Attorney to ACLU of Delaware (Aug. 31, 2012), Public Records Responses, p. 9284, http://
www.aclu.org/files/FilesPDFs/ALPR/delaware/alprpra_ncc_newcastlecountyde%20(2).pdf.
xiii.	 Dutchess County Sheriff’s Office, Response to New York Civil Liberties Union Records Request (Dec. 7, 2012), Public
Records Responses, p. 14943, http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_duchesscountysheriffsoffice_
poughkeepsieny_1.pdf.
xiv.	 High Point Police Department, General Order on Automated License Plate Readers (June 1, 2011), Public Records
Responses, p. 811, http://www.aclu.org/files/FilesPDFs/ALPR/north-carolina/alprpra_HighPointPD_HighPointNC%20(3).pdf.
xv.	
Highland Village Police Department, General Order on Automated License Plate Readers (Sept. 23, 2011), Public Records
Responses, p. 2824, http://www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_highlandpd_highlandvillagetx%20(7).pdf.
xvi.	 Charlotte-Mecklenburg Police Department, Standard Operating Procedure on License Plate Readers (Apr. 29, 2011), Public
Records Responses, p. 1250, http://www.aclu.org/files/FilesPDFs/ALPR/north-carolina/alprpra_charlotte-mecklenburgpd_
charlotte-mecklenburgnc%20(1).pdf.
xvii.	 Aurora Police Department, Special Order on Automated License Plate Readers (Dec. 14, 2011), Public Records Responses,
p. 7708, http://www.aclu.org/files/FilesPDFs/ALPR/colorado/alprpra_aurorapd_auroraca%20(2).pdf.
xviii.	 Commerce City Police, Policy and Procedures Manual (Feb. 1, 2011), Public Records Responses, p. 7916, http://www.aclu.
org/files/FilesPDFs/ALPR/colorado/alprpra_commercecitypd_commercecityca%20(13).pdf.
xix.	 Los Angeles County Sheriff’s Department, Field Operations Directive on Automated License Plate Recognition (ALPR)
System (Aug. 17, 2009), Public Records Responses, p. 4886, http://www.aclu.org/files/FilesPDFs/ALPR/missouri/alprpra_
professionaldevelopmentandresearchbureau_kansascitymo_1.pdf.
xx.	 Email between Plano Police Department and PlateScan (May 11, 2010), Public Records Responses, p. 13906, http://www.
aclu.org/files/FilesPDFs/ALPR/texas/alprpra_planopd_planotx%20(16).pdf.
xxi.	 Delaware State Police, Automated License Plate Reader Policy (Sept. 2010), Public Records Responses, p. 4743, http://www.
aclu.org/files/FilesPDFs/ALPR/delaware/alprpra_delawarestatepolice_de.pdf.
xxii.	 New Jersey Attorney General, Guidelines for the Use of Automated License Plate Readers and Data (Dec. 3, 2010),
Public Records Responses, p. 6144, http://www.aclu.org/files/FilesPDFs/ALPR/new-jersey/alprpra_divisionofcriminaljustice_
trentonnj_1%20(6).pdf.
xxiii.	 Letter from Grapevine Police Department to ACLU of Texas (Sept. 10, 2012), Public Records Responses, pp. 2423-24, http://
www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_grapevinePD_grapevineTX(6).pdf.
xxiv.	 Mesquite Police Department, Response to ACLU of Texas Records Request, Public Records Responses, pp. 10465-66, http://
www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_mesquitepd_mesquitetx%20(2).pdf.
xxv.	 See generally Documents from Yonkers Department of Law in Response to New York Civil Liberties Union Records
Request, Public Records Responses, pp. 15894-15943, http://www.aclu.org/files/FilesPDFs/ALPR/new-york/alprpra_
yonkerspolicedepartment_yonkersny_1.pdf.

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retention policies are of the police department that collected it.65 It is unclear
what NCR’s retention policy is, or whether it even has one, but when license plate
information is shared via NCR’s system, the receiving agency may store and use
that data “in compliance with [its own] data retention policy.”66 Accordingly, any
law enforcement agencies obtaining Greenbelt’s data through NCR may retain it
indefinitely.
• License plate data are widely shared in California’s Bay Area through the
Northern California Regional Intelligence Center (NCRIC), although the full
extent of sharing is not publicly known.67 According to a May 2012 document, this
fusion center’s goal is to collect license plate information from approximately 22
police departments, and grant access to several more.68 NCRIC maintains a broad
mandate for its use of license plate information — in addition to law enforcement,
NCRIC maintains that it may use license plate information for the “protection of
special events; protection of critical infrastructure; and responding and mapping
the license plate landscape of critical events.”69
• Very little was known about the use of automatic license plate readers in
Vermont before the ACLU of Vermont joined with other ACLU affiliates across the
country in public records requests for information. The ACLU of Vermont learned
that police departments in all parts of the state were using them, data was being
uploaded to a centralized computer database and retained for four years, and
no statutes or rules were in place to govern their use. A new law sets statewide
regulations. 70 The law shortens to 18 months the length of time data may be
retained (with longer preservation of data allowed with a court order), clearly
defines who can have access to the data and under what circumstances, and
requires annual reporting on the use of automatic license plate readers and data
requests.

65
Maryland Coordination and Analysis Center, Automatic License Plate Recognition Program Standard Operating Procedure, p.
3 (2012), http://www.mcac.maryland.gov/resources/LPR/20120809_MCAC_LPR_SOP.pdf; City of Greenbelt, Presentation on ELSAG
Automated License Plate Reader & Mobile Plate Hunter 900, Public Records Responses, p. 27451, https://www.aclu.org/nationalsecurity-technology-and-liberty/response-public-records-request-3-greenbelt-police.
66
National Capital Region’s License Plate Reader Information Sharing Program, Program Requirements, Public Records
Responses, p. 27380, https://www.aclu.org/national-security-technology-and-liberty/response-public-records-request-6-greenbeltpolice.
67
County of San Mateo, NCRIC Answers to Questions Submitted from Potential Vendors, p. 2 (May 22, 2012), http://www.
co.sanmateo.ca.us/Attachments/sharedservices/PDFs/RFP/2012/NCRIC%20RFP1266%20Answers%20To%20Vendor%20Qs.pdf.
68
Id.
69
Id. at pp. 22737-40.
70
23 V.S.A. § 1607, http://www.leg.state.vt.us/docs/2014/Acts/ACT069.pdf.

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PUSHING BACK ON INVASIVE LICENSE
PLATE READER USE
A Success Story

W

ith a little bit of organizing effort and access to the right information, local
communities can act to ensure that police departments implement sensible,
privacy-protective license plate reader policies.
That’s what happened in Brookline, Mass., where the ACLU of Massachusetts and local
activists came together to work with the city government to implement a data policy
that both enables law enforcement to use the tool to great public safety benefit and
mitigates the serious privacy harms that result from its unregulated deployment.
Kade Crockford, director of the Technology for Liberty Project at the ACLU of
Massachusetts, tells the story:
Massachusetts has a fairly unique town government structure, but people who live
in states with strong town or county powers can follow the Brookline model to great
effect. Our organizing followed some basic principles.

First, find out what’s going on. In order to do that, we did a cursory web search to see
what kind of information existed in the public sphere. We found that the state had
recently received funding from the federal government that it planned to use to purchase
license plate readers for city and state law enforcement. Alarmingly, the state website
describing the grant said that all police departments that received funds would be
required to submit all captured license plate data to the state criminal justice database.
That alerted us to a serious threat: the possibility that the state would amass detailed
records of our driving habits, all without warrants or any probable cause whatsoever.
Next we filed a public records request to find out which cities and towns had received
funding from the state. Upon receiving those records, we learned that Brookline — an
affluent Boston suburb with a higher-than-average ratio of privacy advocates to
residents — was on the list.
We then began the next phase of our organizing: getting the word out.
Working with activists in Brookline, we penned op-eds in the local newspapers,
warning residents and town government officials that if the police accepted the state

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grant money, all of their motoring movements would be shared with the state, and
the city would lose control over the data forever. It made for a convincing argument,
and the local government held a hearing about the matter.
The last step was turning out like-minded people to join us in raising concerns. We
asked interested residents to come to the hearing to deliver testimony arguing that
the local government should reject the license plate reader grant.
After much back and forth with the town government and lots of discussion in the
local media, Brookline’s Board of Selectmen eventually agreed with us and the
town’s privacy advocates: The plan’s risks outweighed its benefits. The grant was
voted down. Ultimately, our arguments had been so winning that even the chief of
police — a major advocate of license plate reader technology — agreed that it was
probably best to skip the state’s grant, since it was tied to data sharing requirements
that put Brookline residents at risk for privacy violations.
But the fight still wasn’t over.
The police really wanted a license plate reader, and were willing to purchase
it without the help of the state grant. So we continued to work with the police
department, the town government, and local activists, submitting comments on a
proposed license plate reader policy that required the police to delete data after
14 days unless it was evidence of a crime or infraction, or the police were required
to retain it by law. The ACLU doesn’t agree with everything in the Brookline policy,
but it nonetheless stands out as one of the best we’ve seen nationwide, with a
data retention period of 14 days.
After we successfully raised the issue throughout the town, the government knew
that it had to consider the public’s input before approving any license plate reader
or policy. We found that the democratic process worked, as long as ordinary people
were willing to put the work in. Our organizing effort showed that active, alert
residents can affect major policy decisions on the local level.
If you have the time and energy to invest in holding your police department
accountable, you can do it, too. If you aren’t sure about whether or not your
department uses license plate readers or has a good data policy, go to your next
local government meeting and raise the issue.
A little effort goes a long way towards making sure we are both safe and free, no
matter what technologies come down the road.

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THE FEDERAL GOVERNMENT IS
FUELING STATE AND LOCAL USE
OF LICENSE PLATE READERS
Federal funding has fueled the spread of license plate readers among state and local
law enforcement agencies. The Wall Street Journal reported in 2012 that, over the past
five years, the Department of Homeland Security distributed over $50 million in grants
to fund the acquisition of license plate readers.71 Company materials corroborate the
major role that federal funding plays. According to a government “grant guide” on the
website of license plate reader manufacturer ELSAG North America, the Department of
Homeland Security has distributed “billions of dollars in grants” through the Homeland
Security Grant Program and the Infrastructure Protection Program.72 ELSAG’s website
also states that the Justice Department is the “lead Federal funding agency.”73 Federal
money plays such a critical role in supporting the purchase of license plate readers that
PIPS Technology, another major manufacturer, maintains Grant Assistance Coordinators
on staff to work directly with police departments applying for government funds.74
Documents obtained by the ACLU are replete with examples of local and state agencies
building license plate reader networks with federal grant money. Police departments
that would otherwise be limited by local budgets have received tens of thousands or
hundreds of thousands of dollars from the federal government to establish or expand
license plate reader programs. To provide just a few examples:
• Many police departments received grants from the Department of Homeland
Security. For example, San Rafael, Calif., purchased four license plate reader
cameras with a grant of $19,040.75 El Paso County, Texas, purchased license plate
readers with $90,000 out of a $2.5 million grant to improve security at the U.S.
border.76
• The Department of Justice was also a key source of funding. For example, New
Castle County, Del., purchased a system that included eight license plate readers

71
Angwin & Valentino-Devries, supra note 10.
72
ELSAG North America, Grant Guide, http://elsag.com/grant_guide.htm.
73
Id.
74
PIPS Technology, Police Grants Help, http://pipstechnology.com/contact/grants/.
75
San Rafael City Council, Resolution No. 13309 (Mar. 19, 2012), Public Records Responses, pp. 3-4, http://www.aclu.org/files/
FilesPDFs/ALPR/california/alprpra_sanrafaelpd_sanrafaelca%20(1).pdf.
76
CBP, Revised Operations Order Report FY 2011, Operation Stonegarden El Paso (July 16, 2012), Public Records Responses, p.
2371, http://www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_elpasosheriffsoffice_elpasotx%20(3).pdf.

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with a grant of $200,000.77 Hutchinson, Kan., purchased a system that included
four license plate readers with a grant of $24,000.78 The Maryland Transportation
Authority Police purchased a system that included 14 license plate readers with a
grant of $161,000.79 Edison, N.J., purchased one license plate reader with $20,223
out of a $22,076 grant.80 Cheyenne, Wyo., purchased a system that included two
license plate readers with $19,017.63 out of a $48,472 grant.81

77
DOJ Memo to New Castle County Police Department and Invoices (Aug. 21, 2009), Public Records Responses, p. 9287-93, http://
www.aclu.org/files/FilesPDFs/ALPR/delaware/alprpra_ncc_newcastlecountyde (2).pdf.
78
Letter from Kansas Criminal Justice Coordinating Council to Hutchinson Police Department (June 8, 2011), Public Records
Responses, p. 351, https://www.aclu.org/files/FilesPDFs/ALPR/kansas/alprpra_hutchinsonpd_hutchinsonka (4).pdf; Invoices
from PIPS Technology (Apr. 28, 2011), Public Records Responses, p. 349, https://www.aclu.org/files/FilesPDFs/ALPR/kansas/
alprpra_hutchinsonpd_hutchinsonka (3).pdf.
79
Letter to Maryland Transportation Authority Police (July 31, 2009), Public Records Responses, p. 534, http://www.aclu.org/
files/FilesPDFs/ALPR/maryland/alprpra_MarylandTransportationAuthorityandPolicy_md.pdf; Maryland Transportation Authority
Special Report (Aug. 11, 2009), Public Records Responses, p. 535, http://www.aclu.org/files/FilesPDFs/ALPR/maryland/alprpra_
MarylandTransportationAuthorityandPolicy_md.pdf.
80
Letter from Edison Police Department to New Brunswick Police Department (Apr. 17, 2012), Public Records Responses, p. 16804,
http://www.aclu.org/files/FilesPDFs/ALPR/new-jersey/16802-16810 Edison 2nd Supp Response.pdf.
81
DOJ Grant Award Letter and Invoice (Aug. 19, 2011), pp. 3976-78, http://www.aclu.org/files/FilesPDFs/ALPR/wyoming/
alprpra_cheyennepolicedepartment_cheyennewy_1.pdf.

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TOO LITTLE IS KNOWN ABOUT
THE FEDERAL GOVERNMENT’S
OWN USE OF LICENSE PLATE
READERS
In addition to funding state and local purchases of license plate readers, some federal
agencies maintain their own networks of license plate readers across the United States,
and engage in data-sharing on a national level. Unfortunately, too little is known about
how the federal government uses license plate data. As part of our public records
initiative we filed Freedom of Information Act requests with the Departments of Justice,
Homeland Security, and Transportation, but received few voluntary responses and have
had to file a federal lawsuit to force the departments to respond. As of this writing, that
litigation is ongoing (we will update this report once we obtain responsive documents).
For now, here is what we do know:
• Customs and Border Protection uses license plate readers to scan the license
plates of almost every car entering the United States, as well as many cars
leaving the country.82
• Immigration and Customs Enforcement has experimented with operating license
plate readers as well.83 It has also looked into purchasing access to private
repositories of plate data.84
• The Drug Enforcement Administration had deployed cameras in Arizona, Texas,
New Mexico, and California as of 2012,85 and was working to expand its network
of license plate readers throughout the northern and southern borders, as well
as in “hub cities and the high-traffic corridors.”86

82
DHS reports indicate that since 2009, CBP’s license plate readers have logged “nearly 100 percent of land border traffic.”
Department of Homeland Security, Northern Border Strategy, p. 17 (June 2012), http://www.dhs.gov/xlibrary/assets/policy/dhsnorthern-border-strategy.pdf.
83
ICE National Bulk Cash Smuggling Center, internal email (Sept. 13, 2011), Public Records Responses, p. 16167, http://www.aclu.
org/files/FilesPDFs/ALPR/federal/ICE/16147-16228%20r_Pages%20from%20Bulk%20Cash%20Combined-1.pdf.
84
ICE, internal emails (Jan. 2011), Public Records Responses, pp. 21223-24, https://www.aclu.org/files/FilesPDFs/ALPR/federal/
ICE/21201-21224 r_ALPR Privacy Documents.pdf.
85
G.W. Schultz, DEA installs license-plate recognition devices near Southwest border, Ars Technica (July 11, 2012), http://arstechnica.
com/tech-policy/2012/07/dea-installs-license-plate-recognition-devices-near-southwest-border/.
86
Jay Stanley, DEA Recording Americans’ Movements on Highways, Creating Central Repository of Plate Data, ACLU Free Future (May
18, 2012), http://www.aclu.org/blog/technology-and-liberty-criminal-law-reform/dea-recording-americans-movements-highwayscreating.

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PRIVATE COMPANIES COLLECT
LICENSE PLATE DATA WITH NO
OVERSIGHT
License plate readers are used not only by law enforcement agencies but also by private
companies. This has led to the emergence of numerous privately owned databases
containing the location information of vast numbers of Americans.
License plate readers are used in a variety of non-law enforcement roles. Private
companies use license plate readers to monitor airports, control access to gated
communities, enforce payment in parking garages, and even help customers find
their cars in shopping mall parking lots.87 While these uses in and of themselves are
not objectionable, private companies can scan thousands of plates each day and store
information indefinitely, creating huge databases of Americans’ movements.
Perhaps the largest private users of license plate readers are repossession agents who
have recognized the value of license plate location information and built enormous private
databases with data from all over the country. MVTrac, one of the biggest companies in this
industry, claims to have photographs and location data on “a large majority” of registered
vehicles in the United States,88 while the Digital Recognition Network (DRN) boasts of
“a national network of more than 550 affiliates.”89 These affiliates, most of whom are
repossession agents, are located in every major metropolitan area of the United States.
DRN fuels rapid growth of its database by offering to fully finance up to five automatic
license plate readers for affiliates located in major metropolitan areas, such as New York,
Los Angeles, Orlando, Boston, and Washington, D.C., which guarantee they will provide
DRN with a minimum of 50,000 aggregate plate scans per month.90 DRN affiliates feed
location data on up to 50 million vehicles each month (nearly all of which are not wanted
for repossession) into DRN’s national database.91 This database now contains over 700
million data points on where American drivers have been.92
Private companies have partnerships with law enforcement. Police departments
87
Michael Harlow, License Plate Recognition: It’s Grown Far Beyond Airports, Parking Today (July 2009), http://www.parkingtoday.
com/articledetails.php?id=788; Martha Groves, Servant or Snoop in the Parking Garage?, L.A. Times (Jan. 23, 2011), http://articles.
latimes.com/2011/jan/23/local/la-me-santa-monica-parking-20110123.
88
Angwin & Valentino-Devries, supra note 10.
89
Digital Recognition Network, http://www.drndata.com/index.html.
90
MVConnect, LLC et al v. Recovery Database Network, Inc. et al, No. 3:10-cv-01948 (N.D. Tex. Jan. 20, 2011), Amended Complaint,
Exhibit 8, ECF No. 31-8. Title to the ALPRs is not transferred from DRN to the affiliates until they have contributed a total of 1,000,000
plate scans.
91
Digital Recognition Network, http://www.drndata.com/index.html.
92
Id.

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can purchase license plate reader data from private corporations. For example, law
enforcement agencies can access MVTrac’s database and search through data collected
by private repossession agencies.93 DRN contributes its affiliate-generated data to the
National Vehicle Location Service (NVLS), which is run by Vigilant Solutions, a partner of
DRN. NVLS aggregates DRN’s data with data received from other private sources, such as
access control and parking systems, and from law enforcement agencies.94 According to
Vigilant, NVLS “is the largest [license plate] data sharing initiative in the United States.”95
The database holds over 800 million license plate reader records,96 and is used by over
2,200 law enforcement agencies and 25,000 United States law enforcement investigators.97
Each month, the system adds roughly 1,000 new users98 and grows by 35 to 50 million
license plate reader records.99 Law enforcement agencies that use or have used NVLS
include the Milpitas Police Department in California,100 police in Port Arthur, Texas,101 and
Immigration and Customs Enforcement.102
These private databases raise serious privacy concerns. Their massive size suggests that
they contain a great deal of information about our movements. These huge databases of
plate information are not subject to any data security or privacy regulations governing
license plate reader data. These companies decide who can access license plate data and
for what purposes.
Last year, California considered a bill103 that would have required private companies to
delete license plate records after 60 days and regulated the sale and sharing of privately
held plate data. Due in part to the companies’ vigorous opposition, as well as that of law
enforcement agencies, the bill died on the Senate floor.104 Today, these companies continue
to operate with no regulation of how they use the data they are rapidly collecting.

93
Angwin & Valentino-Devries, supra note 10; MVTRAC, Law Enforcement, http://mvtrac.com/law-enforcement/; MVTRAC,
MVENFORCE, http://mvtrac.com/law-enforcement/mvenforce/.
94
Vigilant Solutions, National Vehicle Location Service FAQs, http://nvls-lpr.com/nvls/nvls_faq.html?pp=1#ans9.
95
Vigilant Solutions, National Vehicle Location Service (NVLS), http://vigilantsolutions.com/products/nvls.
96
Vigilant Video, National Vehicle Location Service, p. 2 (2012), http://vigilantsolutions.com/wp-content/uploads/2012/09/VigilantNVLS-Datasheet-092012.pdf.
97
Id.
98
Supra note 24.
99
Vigilant Solutions, National Vehicle Location Service (NVLS), http://vigilantsolutions.com/products/nvls.
100 Letter from Milpitas Police Department to ACLU of Northern California (Aug. 8, 2012), Public Records Responses, p. 128, http://
www.aclu.org/files/FilesPDFs/ALPR/california/alprpra_milpitaspd_milpitasca.pdf.
101 Port Arthur Police Department, Invoice from Vigilant Video for Annual Subscription Renewal, Public Records Responses, p. 2062,
http://www.aclu.org/files/FilesPDFs/ALPR/texas/alprpra_portharthurPD_portarthurtx (6).pdf.
102 ICE, internal emails (Jan. 2011), Public Records Responses, pp. 21223-24, https://www.aclu.org/files/FilesPDFs/ALPR/federal/
ICE/21201-21224 r_ALPR Privacy Documents.pdf.
103 S.B. 1330 (introduced on Feb. 23, 2012), http://www.leginfo.ca.gov/pub/11-12/bill/sen/sb_1301-1350/sb_1330_bill_20120529_
amended_sen_v96.pdf. For further discussion, see Farivar, supra note 24.
104 Press Release, Digital Recognition Network, Digital Recognition Network Defeats California SB1330 (June 5, 2012), http://web.
archive.org/web/20121209024203/http://drndata.com/pdf/CASB1330Releasev2.060512.pdf; Angwin & Valentino-Devries, supra note 10.

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DATA MINING LICENSE PLATE RECORDS
If privacy protections aren’t instituted, we can expect license plate readers to be
used in many new ways and new places. In particular, we can expect all kinds of
cross-referencing and data mining techniques to be applied to the information
streams generated by license plate reader scanners.

We could easily see scenarios such as:
A DEA risk-analysis system alerts the police in Utah that the same car is
traveling between Salt Lake City and Nogales, Ariz., on a monthly basis.
The next night, a divorced father visiting his child in Arizona receives
a knock on the door from federal agents to interrogate him about his
travel. Drug dealer or dedicated dad? Data-mining systems can’t tell the
difference.
An affluent suburbanite has a friend who lives in a poor neighborhood where
drugs are often sold. The police get an alert that he is a regular visitor to
this neighborhood, and he gets pulled over on a pretext (“driving erratically”)
several times so they can search his car, and a police “intelligence squad”
opens a file on him.
A student working nights as a bartender gets stopped
frequently on suspicion of DUI because the police know
that she is driving home from a bar.
The FBI begins investigating a man because he visited a series of places
— a mosque, a hardware store, and a money-transfer service — that
the government’s computers have flagged as “suspicious.” But he’s a
perfectly law-abiding Home Depot employee and practicing Muslim who
helps out his extended family in Somalia.
The FBI opens a probe into the background of a kindergarten teacher because
her car was parked at an apartment building — and then coincidentally again
later at a store — at the same time as a man who is on a terrorist watch list.
Agents appear at her workplace to interview her co-workers.

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THERE ARE TOO FEW RULES IN
PLACE TO PROTECT PRIVACY
Given that license plate readers facilitate the mass collection of information on
Americans’ movements, that too many jurisdictions are retaining data on innocent
Americans for long periods of time, and the inevitable trend towards greater sharing of
this data, it is apparent that there are too few rules in place to ensure that license plate
reader technology is not abused.
In a small 2009 survey, over half of responding agencies that used license plate readers
had no policy addressing license plate reader use.105 Among the agencies that did have
or were developing license plate reader policies, most policies did not address data
retention (52 percent) or data sharing (56 percent).106
Only five states have laws on the books governing license plate readers, and the laws
have different approaches as well as strengths and weaknesses.107 New Hampshire
all but bans license plate readers with narrow exceptions for EZ-Pass and for use by
government agencies at public buildings and three named bridges in Portsmouth.108
Maine prohibits all private use of license plate readers (except as part of an EZ-Pass
system) and requires law enforcement to delete captured plate data that is not part of
a criminal or intelligence investigation within 21 days.109 Arkansas strictly limits private
use of license plate readers, requires captured plate data that is not part of an ongoing
investigation to be deleted within 150 days and prohibits all sharing unless it is evidence
of an offense.110
105 David J. Roberts & Meghann Casanova, International Association of Chiefs of Police, Automated License Plate Reader Systems:
Policy and Operational Guidance for Law Enforcement, p. 25 (2012), http://www.theiacp.org/portals/0/pdfs/IACP_ALPR_Policy_
Operational_Guidance.pdf.
106 Id.
107 These states are New Hampshire, Maine, Arkansas, Vermont, and Utah. N.H. Rev. Stat. Ann. § 261:75-b (2007), http://www.
gencourt.state.nh.us/rsa/html/xxi/261/261-75-b.htm; Me. Rev. Stat. tit. 29-A, § 2117-A (2010), http://www.mainelegislature.org/
legis/statutes/29-a/title29-Asec2117-A.html; H.B. 1996, 89th Gen. Assemb., Reg. Sess. (Ark. 2013), http://www.arkleg.state.ar.us/
assembly/2013/2013R/Acts/Act1491.pdf; Sec. 1. 23 V.S.A. § 1607, http://www.leg.state.vt.us/DOCS/2014/ACTS/ACT069.PDF; 2013
Utah Laws Ch. 447 (S.B. 196), http://le.utah.gov/~2013/bills/sbillenr/SB0196.htm. In addition, Virginia’s Attorney General has issued
an advisory opinion concluding that the state’s Government Data Collection and Dissemination Practices Act prohibits state law
enforcement’s use of license plate readers for passive data collection — that is, collecting and pooling the license plate information of
every car that passes them by. Instead, license plate readers can only be used “actively” — that is, in pursuit of particularly identified
license plates “evaluated and determined to be relevant to criminal activity.” Attorney General Opinion 12-073, p. 1 (Feb. 12, 2013),
http://www.oag.state.va.us/Opinions%20and%20Legal%20Resources/OPINIONS/2013opns/12-073%20Flaherty.pdf. Also, New Jersey’s
Attorney General has issued a directive regarding license plate reader use. The directive requires all New Jersey law enforcement
agencies to retain license plate reader data for five years and contemplates data-mining and pattern analysis of the captured plate data
“to detect suspicious activities that are consistent with the modus operandi of criminals.” Attorney General Directive No. 2010-05, p. 2
(Dec. 3, 2010), http://www.state.nj.us/oag/dcj/agguide/directives/Dir-2010-5-LicensePlateReadersl-120310.pdf.
108 N.H. Rev. Stat. Ann. § 261:75-b (2007), http://www.gencourt.state.nh.us/rsa/html/xxi/261/261-75-b.htm.
109 29-A M.R.S.A. § 2117-A (available on Westlaw)
110 H.B. 1996, 89th Gen. Assemb., Reg. Sess. (Ark. 2013), http://www.arkleg.state.ar.us/assembly/2013/2013R/Acts/Act1491.pdf.

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RECOMMENDATIONS
To ensure that license plate readers can be used by law enforcement agents for
legitimate purposes without infringing on Americans’ privacy and other civil liberties, the
ACLU calls for the adoption of legislation and law enforcement agency policies adhering
to the following principles:
• License plate readers may be used by law enforcement agencies only to
investigate hits and in other circumstances in which law enforcement agents
reasonably believe that the plate data are relevant to an ongoing criminal
investigation. The police must have reasonable suspicion that a crime has
occurred before examining collected license plate reader data; they must not
examine license plate reader data in order to generate reasonable suspicion.
• Law enforcement agencies must not store data about innocent people for any
lengthy period. Unless plate data has been flagged, retention periods should be
measured in days or weeks, not months, and certainly not years.
• It is legitimate to flag plate data (1) whenever a plate generates a hit that is
confirmed by an agent and is being investigated, (2) in other circumstances in
which law enforcement agents reasonably believe that the plate data are relevant
to a specific criminal investigation or adjudication, (3) when preservation is
requested by the registered vehicle owner, or (4) when preservation is requested
for criminal defense purposes.
• Once plate data has been flagged, a longer retention period commensurate with
the reason for flagging is appropriate.
• Law enforcement agencies must place access controls on license plate reader
databases. Only agents who have been trained in the departments’ policies
governing such databases should be permitted access, and departments should
log access records pertaining to the databases.
• People should be able to find out if plate data of vehicles registered to them are
contained in a law enforcement agency’s database. They should also be able to
access the data. This policy should also apply to disclosure to a third party if the
registered vehicle owner consents, or for criminal defendants seeking relevant
evidence.
• Law enforcement agencies should not share license plate reader data with third
parties that do not conform to the above retention and access principles, and
should be transparent regarding with whom license plate reader data are shared.

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• Hot lists should be updated as often as practicable and, at a minimum, at the
beginning of each shift. Whenever a license plate reader alerts on a plate, law
enforcement, before taking any action, should be required to confirm visually that
a plate matches the number and state identified in the alert, confirm that the
alert is still active by calling dispatch and, if the alert pertains to the registrant
of the car and not the car itself, for example in a warrant situation, develop a
reasonable belief that the vehicle’s occupant(s) match any individual(s) identified
in the alert.
• Any entity that uses license plate readers should be required to report its usage
publicly on at least an annual basis.

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ACKNOWLEDGMENTS
This report has been a project of the American Civil Liberties Union. The primary
author is Catherine Crump, staff attorney, Speech, Privacy & Technology Project. The
ACLU would also like to acknowledge the following individuals who made substantial
contributions to this report: Ibrahim Alsaygh, Christina Argueta, Josh Bell, David
Benhamou, Tess Bloom, Allie Bohm, Stevaughn Bush, Matt Cagle, Kade Crockford,
Sandra Fulton, Naomi Gilens, Katherine Haas, Brian Hauss, Mike Katz-Lacabe, Doug
Klunder, Mica Moore, Sejal Singh, Jay Stanley, Bennett Stein, Nathan Freed Wessler,
Ben Wizner, and Noa Yachot. Thanks also to the participants in the NYU Technology Law
and Policy Clinic, and professor Jason Schultz, for their valuable feedback.
The ACLU would like to thank the following affiliates for participating in this multi-state
coordinated public records request: Alaska, Arizona, Northern California, Colorado,
Connecticut, Delaware, Florida, Georgia, Hawaii, Illinois, Iowa, Kansas/W. Missouri,
Kentucky, Louisiana, Maryland, Massachusetts, Minnesota, Nebraska, Nevada, New
Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania,
Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington,
D.C., and Wyoming.

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