Automatic License Plate Readers (ALPRs) are becoming increasingly common tools used by law enforcement. Mounted on police cars or fixed in strategic locations, these devices automatically scan license plates of passing vehicles. But what exactly are ALPRs, and what are the implications for drivers and their privacy? This article delves into the technology behind police cars that automatically scan license plates, exploring how they work and the growing concerns surrounding their use.
Understanding Automatic License Plate Reader Technology
Automatic license plate readers are sophisticated surveillance systems that utilize high-speed cameras and computer processing to capture and interpret vehicle license plates. These systems, often deployed on police vehicles, can scan thousands of license plates per hour, significantly enhancing law enforcement’s ability to monitor vehicle movements. At a minimum, an ALPR system records the license plate number, along with the date, time, and geographical coordinates of each scan.
Modern ALPR technology employs specialized digital cameras and powerful computer algorithms to rapidly process vast quantities of license plate images. These images are instantly converted into text and cross-referenced against extensive databases, commonly known as “hot lists.” These hot lists may include vehicles associated with various categories, ranging from stolen vehicles and wanted individuals to vehicles linked to parking violations or even broader watch lists. When a scanned license plate matches an entry on a hot list, the system immediately alerts law enforcement personnel.
Privacy Concerns and the Broad Net of ALPRs
A critical issue with automatic license plate readers is that they record every license plate they scan, regardless of whether the vehicle is of interest to law enforcement. This indiscriminate data collection means that vast amounts of information about law-abiding citizens are being captured and stored. As technology advances, the sheer volume of data ALPRs can collect is only limited by the number of vehicles passing within camera range.
Consider the example of the Rhinebeck Police Department, which scanned 164,043 license plates in just three months, yet only eight of those were flagged as being of interest. This represents a staggering 99.99 percent “failure rate,” highlighting the massive collection of data on innocent individuals. The privacy implications of such widespread location data collection are profound.
The International Association of Chiefs of Police has acknowledged these concerns, cautioning that “mobile LPR units could read and collect the license plate numbers of vehicles parked at addiction counseling meetings, doctors’ offices, health clinics, or even staging areas for political protests.” This capability can have a chilling effect on fundamental rights, such as freedom of association and political expression. Furthermore, without robust privacy safeguards, the data collected by ALPRs can be stored indefinitely and potentially shared between various government agencies and even private entities, creating a comprehensive record of individuals’ movements and habits.
To illustrate the depth of information that can be gathered, consider a case study where the City of Beacon Police Department provided ALPR records for one week. Analysis of just one vehicle’s data revealed its location was recorded 24 times in that single week. By using mapping tools, it was possible to pinpoint the car’s presence on Beacon’s Main Street multiple times, even indicating overnight parking. This limited dataset already provides a surprisingly detailed picture of the vehicle owner’s routine.
Extended over longer periods, across multiple ALPR units, and combined with advanced data analytics, the information gathered by police cars automatically scanning license plates can create an incredibly detailed and intrusive portrait of an individual’s life, even without any suspicion of wrongdoing.
The Proliferation of Automatic License Plate Readers
Automatic license plate readers are not limited to major cities; they are becoming increasingly prevalent even in smaller municipalities. As of 2013, New York State had funded over 422 ALPR systems across every county. Moreover, state-level law enforcement agencies like the New York State Police and Department of Motor Vehicles also operate these systems.
Density of Automatic License Plate Readers per 100,000 Residents in New York State
Darker areas on the map indicate a higher concentration of automatic license plate readers relative to population.
Even small villages with populations under 3,000 residents have adopted ALPR technology. In larger urban centers like New York City, the NYPD operates hundreds of ALPRs as part of its Domain Awareness System, integrated with a network of security cameras and other surveillance tools. The widespread deployment of ALPRs means that vehicle movements are being tracked across a broad geographical area, regardless of location size or population density.
Data Access and Sharing: Expanding the Surveillance Network
The reach of ALPR data extends beyond the individual agencies that operate the systems. Data sharing among law enforcement entities is common practice. For instance, in Westchester County, various federal, state, and local agencies collaborate through the Westchester Intelligence Center, pooling and sharing ALPR data. Similar data-sharing initiatives exist in other regions, such as the Albany Crime Analysis Center.
Furthermore, some law enforcement agencies are partnering with private companies that maintain vast commercial databases of license plate information. Vigilant Solutions, for example, offers access to a nationwide database containing billions of license plate records collected from both private and law enforcement ALPRs. This database is continually growing, capturing tens of millions of new data points each month. Agreements like the one between the NYPD and Vigilant Solutions illustrate how law enforcement can tap into an even broader surveillance network, extending their reach beyond their own ALPR deployments. This access allows agencies to monitor vehicle locations across a wider geographical area, track vehicle history, conduct virtual stakeouts, and identify associations between vehicles, raising significant privacy implications.
The Need for Clear Policies and Regulations
The lack of consistent statewide or national policies governing the use of automatic license plate readers is a major concern. Current policies and procedures vary significantly across different localities, and many jurisdictions lack adequate safeguards for the collection, use, retention, and sharing of ALPR data.
Westchester County, despite having a high concentration of ALPRs, serves as an example of this policy gap. The Westchester County Department of Public Safety, operating multiple ALPR units, lacked a written policy regarding ALPR use, data storage, access, or sharing. The department planned to retain location data for a year, even though the vast majority of scans yielded no actionable intelligence. Similarly, Yonkers, another jurisdiction within Westchester County, indefinitely retained all ALPR data collected, also without a clear written policy.
Implementing robust privacy protections is crucial to mitigate the potential chilling effects of ALPR technology and foster trust between communities and law enforcement. Local governments and law enforcement agencies should prioritize the adoption of clear and comprehensive policies that address public privacy concerns before deploying and utilizing automatic license plate readers. These policies should include limitations on data retention, strict rules on data access and sharing, and mechanisms for transparency and accountability to ensure that the use of these powerful surveillance tools is appropriately governed and respects individual privacy rights.
Further Reading: For a broader overview of ALPR use across the United States, see the ACLU report “You Are Being Tracked: How License Plate Readers Are Being Used to Record Americans’ Movements.”
References:
- New York State Division of Criminal Justice Services, License Plate Reader Suggested Guidelines, Jan. 2011.
- Rhinebeck Police Department FOIL Response: Quarterly License Plate Reader Progress Report Apr.-Jun 2011.
- International Association of Chiefs of Police, Privacy Impact Assessment Report for Utilization of License Plate Readers (Sept. 2009).
- New York State Division of Criminal Justice Services (DCJS) FOIL Response (Aug. 27, 2013).
- 2010 Census of Population and Housing, U.S. Census Bureau.
- Testimony of Deputy Commissioner of Intelligence and Counterterrorism John J. Miller, NYPD, Nov. 12, 2014.
- Ardsley Village FOIL Response.
- Bedford Town FOIL Response.
- Colonie PD FOIL Response.
- Vigilant Solutions Scope of Work.
- DCJS FOIL Response.
- Westchester County Department of Public Safety FOIL Response.
- City of Yonkers FOIL Response.
