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Automated License Plate Recognition Systems: Policy and Operational Guidance for Law Enforcement

NCJ Number
David J. Roberts; Meghann Casanova
Date Published
128 pages

This project was designed to assess automated license plate recognition (ALPR) implementation among law enforcement agencies in the United States, and to identify emerging implementation practices to provide operational and policy guidance to the field.


Law enforcement agencies are adopting ALPR to: enhance capabilities, expand collection of relevant data, and expedite the process of comparing license plates with lists of vehicles of interest, and it is becoming a significant tool for law enforcement and public safety agencies nationwide. Within seconds ALPR systems automatically capture images of license plates, transform those images into data, compare that data to databases, and alert officers when there is a match. Maximizing the value of ALPR can only be achieved through proper planning, implementation, training, deployment, and management of the technology and the information it provides. Like all law enforcement resources, ALPR must be carefully managed to ensure quality of data, security of the system, compliance with laws and regulations, and privacy of information. A random sample of 500 State, local, and tribal law enforcement agencies was surveyed. A total of 305 agencies responded to the survey (61.0%). Three-quarters of respondents (235 agencies, 77.0%) indicated that they were not using ALPR, while 70 agencies (23.0%) responded that they were using ALPR. A longer, more detailed follow-on survey was sent to the 70 agencies who confirmed they were using ALPR with 40 agencies (57.1%) responding. Respondents typically implemented mobile ALPR systems (95%), and were using ALPR for auto theft (69%), vehicle and traffic enforcement (28%), and investigations (25%). Agencies reported increases in stolen vehicle recoveries (68%), arrests (55%), and productivity (50%). Fewer than half (48%) had developed ALPR policies. Over half (53%) updated their ALPR hot lists wirelessly, and nearly half (43%) updated these lists daily. A total of 40% of respondents retain ALPR data for six months or less. Five respondents (13%) indicated they retain ALPR data indefinitely, while two indicated that retention is based on the storage capacity of the equipment installed.

Date Published: January 1, 2012