License plate readers are in use across most U.S. states, but the rules about how they work and what happens to the data vary widely

License plate readers (also called automatic license plate recognition or ALPR systems) are cameras that photograph vehicle plates and run them against databases to flag stolen cars, missing persons, or vehicles tied to crimes. They are mounted on police vehicles, fixed at intersections, or installed on highway overpasses. Most states have deployed them in at least some jurisdictions, but the states differ sharply in what police can do with the data, how long they keep it, and whether the public can see records of scans.

There is no single national registry of which states have readers or how many. Police departments and highway patrol agencies buy and operate them independently, so coverage within a state can be spotty — a major city might have extensive networks while rural areas have none. What matters more than whether your state "has" readers is what your state law says about retention, access, and oversight.

Key Takeaways

  • License plate readers operate in most states, but state law determines whether police can keep scan data for months or must delete it within days.
  • Some states require a warrant or reasonable suspicion before police can search the database; others allow searches with no legal threshold.
  • A handful of states have passed laws limiting how long data can be stored or requiring public disclosure of reader locations; most have not.
  • You can contact your state legislature or local police department to ask what rules govern readers in your area, since many departments do not publish this information.

States with strict data retention and access rules

A small number of states have passed laws that limit how long police can keep scan records and who can search them. New Hampshire requires deletion of plate data within 30 days unless the plate is flagged as stolen or connected to a crime. Vermont deletes data after 30 days and requires a warrant before police can search the database. Maine requires deletion within 30 days and restricts searches to active investigations.

California requires deletion of data within 60 days unless the plate matches a wanted vehicle or suspect, and the state's attorney general publishes an annual report on reader use. Colorado requires deletion within 90 days and mandates that police document the reason for each search. Connecticut requires deletion within 30 days and restricts access to law enforcement only.

These states are the exception. Most states have no statewide law governing retention or access, which means individual police departments set their own policies — or keep data indefinitely with no written policy at all.

States with minimal or no data protection rules

The majority of states have not passed laws limiting how long police can store plate scan data or who can search it. In these states, police departments may keep records for years, and access rules vary by department. Texas, Florida, Georgia, New York, Pennsylvania, Ohio, Illinois, Michigan, North Carolina, and Virginia all have widespread reader deployment but no statewide law restricting retention or search authority.

In states without statewide rules, a large police department might keep data for six months or longer, while a smaller agency might delete it after 30 days — or never delete it at all. Some departments share data with federal agencies or private companies; others keep it internal. Without a state law, there is no requirement to disclose these practices to the public.

How to find out what rules explore in your state

Your state legislature's website usually has a searchable bill database. Search for terms like "license plate reader," "ALPR," or "automatic license plate recognition." If you find a law, read the section on "data retention" or "retention period" to see how long records are kept, and look for sections on "warrant" or "reasonable suspicion" to see what legal standard police must meet before searching.

If your state has no statewide law, contact your local police department's public information officer and ask: How long does your department keep plate scan data? What legal standard must be met before an officer can search the database? Is the data shared with other agencies or companies? Many departments will not have a written answer, which itself is useful information — it means there is no formal policy.

You can also contact your state representative or senator and ask whether they have introduced or would support a bill setting retention limits and access rules for readers in your state. Several states have passed new laws in the past five years as public awareness has grown.

Federal law and interstate data sharing

There is no federal law that sets a national standard for license plate reader data. The FBI and Department of Homeland Security can access some state and local reader networks, but the rules governing that access vary. Some states have agreements that allow data to be shared across state lines; others do not.

If you travel across state lines, your plate may be scanned in multiple states, and the data may be retained under different rules in each one. A scan in Vermont might be deleted in 30 days, but the same plate scanned in a neighboring state with no retention law might be kept indefinitely.

What readers are used for and what they are not

License plate readers are designed to flag vehicles that match specific criteria: stolen cars, vehicles tied to Amber Alerts, or plates on a wanted-persons list. They are not supposed to be used for general surveillance or to track a person's movements over time. However, without strong state law or oversight, nothing prevents a department from using them that way.

Some police departments have used readers to track protesters, monitor specific neighborhoods, or build location profiles on individuals without a warrant. These uses have sparked lawsuits and legislative pushback in states like California and New York. Whether such use is legal depends on your state's law and, increasingly, on local court rulings.

Recent state law changes

New York passed a law in 2020 requiring police to delete plate data within 30 days and restricting searches to active investigations. Massachusetts passed a law in 2021 requiring deletion within 90 days and mandating annual reports to the legislature. Illinois passed a law in 2022 requiring deletion within 90 days and restricting access to law enforcement.

These changes reflect growing concern about mass surveillance and data retention. If your state has not passed a law yet, it may be considering one. Check your state legislature's website or contact a civil liberties organization in your state — groups like the ACLU often track reader legislation.

Frequently Asked Questions

Can I learn about my license plate has been scanned?

In most states, no. Scan records are not public, and police are not required to tell you that your plate was photographed. A few states, like California, allow you to request records under public records law, but the process can take weeks and police may redact information. Your best option is to contact your local police department and ask about their public records request process.

Do I have a right to know where license plate readers are located?

It depends on your state. California requires police to publish reader locations. Most other states do not. You can file a public records request asking your local police department where readers are installed, but they may refuse on the grounds that the information could help criminals. Some departments publish this information voluntarily.

Can police use license plate readers to track someone without a warrant?

State law varies. In states like Vermont and California, police generally need a warrant or reasonable suspicion. In most other states, there is no legal requirement. Federal courts have not yet ruled that warrantless tracking via readers violates the Constitution, so state law is the main protection.

What should I do if I think my plate was scanned improperly?

File a complaint with your local police department's internal affairs division or civilian review board. You can also contact your state attorney general's office or a civil liberties organization. If you believe your rights were violated, you may have grounds for a lawsuit, but you will need to consult an attorney in your state.

Are there states with no license plate readers at all?

No state has banned readers entirely. However, some rural areas and smaller jurisdictions may not have them because of cost. If you live in a small town, your local police may not operate readers, even if neighboring departments do.