California ALPR FAQs
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How do Automated License Plate Recognition (ALPR) Systems work?
Automated License Plate Recognition (ALPR) systems function to automatically capture an image
of a vehicle and the vehicle’s license plate, transform the plate image into alphanumeric
characters using optical character recognition, compare the plate number acquired to one or
more databases (also known as “hot lists”) of vehicles of interest to law enforcement, and then
alert law enforcement officers when a vehicle of interest has been observed.
The stored license plate data also provides law enforcement investigators with a pointer system
that may help them identify vehicles associated with suspects, witnesses, or victims, and to
develop exculpatory information that assists them with focusing their investigative resources.
The data also allows law enforcement to connect serial criminal activities that may have occurred
in disconnected law enforcement jurisdictions.
https://www.theiacp.org/projects/automated-license-plate-recognition
How do California Law Enforcement Agencies use ALPR?
Law enforcement agencies use ALPR systems for the authorized law enforcement purpose of
rapidly identifying and locating vehicles of legitimate interest to law enforcement.
In one common use of ALPR technology, license plate encounters are compared against law
enforcement databases, also known as “hot lists”. The lists contain the license plate numbers
and letters of vehicles associated with active investigations, such as those related to Amber Alerts
or other missing persons, stolen vehicles, or stolen license plates. The information is also retained
for a fixed retention period, though it is only re-accessible by law enforcement given a legitimate
law enforcement purpose.
A second common use of ALPR technology is to canvas license plates around any crime scene to
assist in the identification of suspects, victims, and witnesses. ALPR technology only acts as a
pointer system that allows law enforcement to conduct searches with limited information,
including partial license plate information.
Where is ALPR data stored?
ALPR data resides in a secure facility with 24/7 security measures in place.
Who has access to the ALPR database?
Only law enforcement personnel that have:
1. An official and legitimate law enforcement purpose for accessing the system.
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2. A criminal case or incident number/name.
3. A lawful purpose with a need to know and right to know the information.
What is a lawful purpose?
The lawful purposes required for users to access the system are
1. Locate Stolen, Wanted, or Suspect Vehicles.
2. Locate Suspect(s) of Criminal Investigation or Arrest Warrant.
3. Locate Witnesses or Victims of Violent Crime.
4. Locate Missing Children and Elderly individuals (Amber / Silver Alerts).
5. Protect the Public during Special Events / Situational Awareness.
6. Protect Critical Infrastructure.
What is a need to know?
This standard is established when the requested information is pertinent and necessary to the
requesting agency in initiating, furthering, or completing the performance of a law enforcement
activity.
What is a right to know?
This standard is established when the requester is acting in an official capacity and has statutory
authority to obtain the information being sought.
How are personnel vetted to have access to the system?
Law enforcement agency personnel must be approved to have access to the system by their
agency.
Once a law enforcement or public safety agency employee is approved to use the system how
do they access the data?
Approved law enforcement agency employees access the system with a unique username and
login.
Does the ALPR system collect my personal identifying information?
The ALPR system does not contain personal identifying information associated with data
collected through ALPR devices. The system only contains the data sets of license plate numbers,
photos of the vehicles, and geospatial locations from where the images were captured. There is
no connectivity in the ALPR system to the vehicle’s registration information or the driver's license
information of the owner.
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How accurate is the ALPR technology?
As ALPR technology is translating optical characters to digital data there is a small error rate in
translation of alphanumeric characters that are similar in shape. ALPR operators must recognize
that the data collected from the ALPR device, and the content of referenced hot lists, consists of
data that may or may not be accurate, despite ongoing efforts to maximize the currency and
accuracy of such data. To the greatest extent possible, law enforcement agencies request that
vehicle and subject information be verified from separate Law Enforcement information sources
to confirm the vehicle or subject’s identity and justification for law enforcement contact. Law
enforcement users of ALPR Data must, to the fullest extent possible, visually confirm that the
plate characters generated by the ALPR readers correspond with the digital image of the license
plate in question.
Can members of the public request the images of where their vehicle has been seen by ALPR?
No, the ALPR systems are restricted to law enforcement personnel with a lawful purpose for
searching the system. If a member of the public’s vehicle or license plate is stolen, law
enforcement agencies with a case number may search the database to search for the stolen
vehicle or license plate and establish an alert to notify them if the license plate is encountered.
How many alerts occur each month for wanted vehicles?
Approximately 1 to 2 vehicles out of 1000 initiate an alert in the system.
How is the system audited?
The system logs each user’s activity by agency, name, date, time, and purpose of search.
Designated law enforcement personnel may perform sample audits to the system to confirm that
it is functioning properly, and that required data is being appropriately submitted.
Is vehicle information shared with private sector companies?
No, the law enforcement ALPR systems are restricted to law enforcement personnel with a lawful
purpose for using the system.
Where are ALPR cameras located?
ALPR units are attached to law enforcement vehicles or deployed at fixed locations, where they
collect license plate information from vehicles on public roadways, public property and vehicles
that are within public view. As the ALPR devices are a law enforcement investigative tool we do
not provide the locations of the cameras. If subjects engaged in violent and/or serial criminal
activities are made aware of the location of the devices, they could take measures to avoid
detection.
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How long are ALPR records maintained?
Most ALPR records are maintained for a set period within California that ranges by jurisdiction
from sixty (60) days to five (5) years with records purged unless the data has become, or it is
reasonable to believed that it will become, evidence in a criminal or civil action or is subject to a
lawful action to produce records. The Northern California Regional Intelligence Center/High
Intensity Drug Trafficking Area (NCRIC/HIDTA) has a one (1) year retention period for ALPR
records, unless the information is collected from a local agency ALPR in an area wherein the local
government has requested a shorter retention period for their agency’s ALPRs.
Why are records maintained for any specific time?
The retention of records allow time for witnesses and victims of crime to report incidents to law
enforcement. It also allows law enforcement to connect serial criminal activities that occur in
disconnected law enforcement jurisdictions. The greatest potential value of an ALPR system is in
identifying vehicles associated with the investigation of violent and serial criminal events. In this
capacity the ALPR system aids law enforcement investigators by providing a pointer system that
may help them identify vehicles associated with suspects, witnesses, victims and to develop
exculpatory information that assists them with focusing their investigative resources.
Do ALPR systems provide constant surveillance of the location of members of the public?
No, ALPR systems only provide authorized law enforcement personnel with a pointer for one
moment in time and location where a vehicle was located to provide potential leads to support
criminal investigations.
Can ALPR devices see into my vehicle?
Unlike red light cameras, ALPR devices do not have illumination to aid in identifying the driver of
the vehicle. The purpose of the ALPR is to identify the vehicle, not the occupants. If ambient
lighting is sufficient or a subject is outside and near the vehicle their image may be captured.
Is every ALPR image reviewed?
No, images are only reviewed by law enforcement personnel when required and based upon the
need to:
1. Locate stolen, wanted, and subject of investigation vehicles.
2. Locate and apprehend individuals subject to arrest warrants or otherwise lawfully sought
by law enforcement.
3. Locate witnesses and victims of violent crime.
4. Locate missing children and elderly individuals, including responding to Amber and Silver
Alerts.
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5. Support local, state, federal, and tribal public safety departments in the identification of
vehicles associated with targets of criminal investigations, including investigations of
serial crimes.
6. Protect participants at special events.
7. Protect critical infrastructure sites.
What laws are there regarding the use ALPR devices?
After California Senate Bill 34 became law, it required transparency of ALPR implementation,
policies, security, and notifications of any data breach. The law also requires law enforcement
agency ALPR system operators to have and post ALPR usage and privacy policies to ensure that
the collection, use, maintenance, sharing, and dissemination of the information is consistent with
respect for individuals’ privacy and civil liberties.
(https://leginfo.legislature.ca.gov/faces/billCompareClient.xhtml?bill_id=201520160SB34&showamends
=false in SEC. 3. Title 1.81.23 (commencing with Section 1798.90.5) Part 4 of Division 3 of the Civil
Code)
Is ALPR data shared for the purpose of immigration enforcement?
No authorized law enforcement user or agency may access California ALPR databases for the
sole purpose of immigration enforcement. In gathering, sharing, and storing information,
California law enforcement agencies comply with all applicable laws, rules, and regulations,
including but not limited to, to the extent applicable, the California Values Act (Government
Code Section 7284 et seq.). Each California law enforcement agency, consistent with California
Government Code Sections 7282, 7282.5, and 7284.8 (b), works to ensure that databases are
governed in a manner that limits the availability of information therein to the fullest extent
practicable and consistent with federal and state law, to anyone or any entity for the purpose
of immigration enforcement.
What is the privacy impact of ALPR?
To learn more about the privacy impact of ALPR please read the NCRIC privacy impact assessment
at https://ncric.org/html/NCRIC%20ALPR%20PIA.PDF. Comments or questions regarding the
ALPR impact assessment may be directed to [email protected].
