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Research Questions

  1. How is license plate reader (LPR) technology presently used?
  2. Are there additional uses for LPR?
  3. What factors or issues constrain its use?
  4. How can the technology be enhanced?

Law enforcement agencies across the country have quickly been adopting a new technology to combat auto theft and other crimes: automated license plate reader (LPR) systems. These systems can capture the image of the license plate of a passing vehicle and compare the plate number against official "hotlists" that show an array of infractions or reasons why it may be of interest to authorities. But because LPR technology is relatively new in the United States, opportunities and obstacles in its use in law enforcement are still under exploration. To examine issues about this technology, RAND conducted interviews with law enforcement officers and others responsible for procuring, maintaining, and operating the systems. Champions of LPR technology exist at many levels, from tech-savvy officers who use it every day, to chiefs who promote it, to other officials and policymakers who believe LPR technology is a significant force multiplier for police departments. Challenges exist, however, to realizing more widespread acceptance and use of the technology. Chief among these are privacy concerns related to the retention and potential misuse of LPR data, technical and bureaucratic impediments to sharing data among law enforcement agencies, and constraints on the availability of staffing and training needed to support LPR systems.

Key Findings

License plate reader (LPR) systems, while initially used to detect stolen vehicles and plates, are increasingly being tapped for a variety of investigations.

  • Authorities can retrieve LPR data to determine vehicles in the vicinity of a crime scene.
  • The system can provide photos of those vehicles to confirm suspect alibis.
  • LPR data can be used to analyze crime patterns.

Many privacy advocates have challenged the practice of storing LPR data not associated with a specific crime.

  • Some police departments lack clear guidance on storing plate data, leaving privacy advocates to fear it can be kept and retrieved indefinitely.
  • Some privacy advocates, departments, and lawmakers have moved to codify police procedures on recording these data; some have banned the technology's use outright.

LPR systems can be beneficial in providing assistance in any type of investigation, provided the necessary data are available to support the systems.

  • Systems with the most database access and longest retention policies are the most beneficial because they can provide the greatest number of alerts and the ability to retrieve LPR data over time across law enforcement activities.
  • System maintenance and data storage can increase cost. If an agency's database can be made part of existing information technology infrastructure, its maintenance costs can be lessened.


  • Estimate and secure necessary funding for the entire lifecycle of LPR technology.
  • Ensure that sufficient infrastructure is in place to handle different types of data promptly and frequently.
  • Develop policies for system data use, access, and storage.
  • Integrate LPR systems into daily agency operations and learn from other agencies how to expand their use to more analytical operations.
  • Develop model memoranda of understanding for agencies to share LPR data.
  • Identify tradeoffs between privacy rights and law-enforcement uses.

The research described in this report was sponsored by the National Institute of Justice and was conducted in the Safety and Justice Program within RAND Justice, Infrastructure, and Environment.

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