Skip Repetitive Navigation Links

Automated License Plate Readers
To Better Protect Individuals’ Privacy, Law Enforcement Must Increase Its Safeguards for the Data It Collects

Report Number: 2019-118

February 13, 2020

The Governor of California
President pro Tempore of the Senate
Speaker of the Assembly
State Capitol
Sacramento, California 95814

Dear Governor and Legislative Leaders:

As directed by the Joint Legislative Audit Committee, my office conducted an audit of local law enforcement agencies’ use of automated license plate readers (ALPR); the following report details the audit’s findings and conclusions. In general, we determined that the law enforcement agencies we reviewed must better protect individuals’ privacy through ensuring that their policies reflect state law. In addition, we found that these agencies must improve their ALPR data security, make more informed decisions about sharing their ALPR data, and expand their oversight of ALPR users.

We reviewed four agencies in detail that operate ALPR systems—Fresno Police Department, Los Angeles Police Department, Marin County Sheriff’s Office, and Sacramento County Sheriff’s Office. An ALPR system collects and stores license plate images of vehicles passing in its view and enables law enforcement to track a vehicle’s movements over time; such a system raises privacy concerns. State law helps address these concerns by requiring agencies to have policies and safeguards in place to protect their ALPR systems from misuse. However, the agencies we reviewed either did not have ALPR policies or their policies were deficient, and they had not implemented sufficient safeguards. For example, none had audited searches of the ALPR images by their staff and thus had no assurance that the searches were appropriate. Furthermore, three of the four agencies have shared their ALPR images widely, without considering whether the entities receiving them have a right to and need for the images. The statewide survey of law enforcement agencies we conducted found that 70 percent operate or plan to operate an ALPR system, and this raises concerns that these agencies may share the deficiencies we identified at the four agencies we reviewed. Because many of the issues we identified link to the agencies’ deficient ALPR policies we recommend that the Legislature direct the California Department of Justice to develop a policy template that local law enforcement agencies can use as a model for their ALPR policies.

Our statewide survey also showed that the period of time law enforcement agencies retain ALPR images varies widely. However, among the four agencies we reviewed none had considered the usefulness of the ALPR images to investigators over time when determining their retention periods. We recommend that the Legislature amend state law to specify a maximum retention period for ALPR images.

Respectfully submitted,

California State Auditor

Back to top