Law enforcement agencies say license plate recognition systems increase public safety, but American Civil Liberties Union affiliates from 35 states, including Virginia and Maryland, are raising questions about what the devices mean for privacy.
The ACLU is asking police and state agencies to better explain how they use automatic license plate readers.
"The concern is that tracking peoples' location may reveal private things about their lives, such as what friends, doctors, protests, political events or churches they visit," says Rebecca Glenberg, the legal director of the ACLU of Virginia. Glenberg says another concern is that the data may be stored indefinitely.
"We recognize that this technology can be legitimately used for narrowly tailored law enforcement purposes like identifying vehicles that are stolen or involved in a crime," she adds.
The ACLU also sent information requests to the departments of Justice, Homeland Security and Transportation for information on how the federal government funds and uses information collected by the license plate readers.
Law enforcement agencies say the devices are a useful tool in enhancing public safety.