License plate scanners read thousands of plates an hour in Charlotte. How it all works

As drivers travel throughout Charlotte and much of North Carolina, systems of cameras are scanning thousands of license plates per hour.

Automatic license plate reader systems, primarily used by local police departments, are useful, law enforcement says.

In addition to helping solve crimes, license plate readers can also help police locate missing persons, such as an 80-year-old man eventually found safe in early December after his vehicle had “several license plate reader hits.”

But the system isn’t perfect, and there are legal protections in place under state law to help prevent license plate readers from being misused or abused.

Here’s what to know about license plate readers and how they’re used in and around Charlotte:

How do automatic license plate reader systems work?

Automatic license plate reader systems are defined by North Carolina law as a “system of one or more mobile or fixed automated high-speed cameras used in combination with computer algorithms to convert images of license plates into computer-readable data.”

Agencies, such as local police departments, who use these systems can then use the data to see where certain cars were at different times.

Are automatic license plate reader systems legal in NC?

Automatic license plate reader systems are allowed in North Carolina, but state law does put some regulations on them.

The law dictates that any agency that uses them, including local police departments, must have a policy that touches on a number of issues, including data retention and security and how data is shared with other law enforcement agencies.

And any data law enforcement gets from license plate readers can be “obtained, accessed, preserved, or disclosed only for law enforcement or criminal justice purposes.”

Any license plate data captured “by or on behalf of a law enforcement agency for law enforcement purposes” can’t be “preserved” for more than 90 days, state law says, unless certain search warrants have been issued.

License plate data is “confidential” and can’t “be disclosed except to a federal, state, or local law enforcement agency for a legitimate law enforcement or public safety purpose.”

Automatic license plate reader systems in Charlotte

The Charlotte-Mecklenburg Police Department is one of multiple law enforcement agencies in North Carolina that uses automatic license plate reader systems, the American Civil Liberties Union found.

A 2019 report by WCNC found CMPD has more than 100 cameras scanning plates throughout the city, each capable of reading up to 3,000 license plates per hour.

But the system doesn’t always work perfectly.

In October, The Charlotte Observer reported previously, CMPD said it would begin providing officers with more training on license plate readers, verify entries more frequently and invite an outside consultant to review its practices after a June 2021 incident in which a mistake with a plate reader led to a local teacher being handcuffed by police at gunpoint.