ALPR 101

What ALPRs Capture

Every Car. All Day. Suspected of Nothing.

An automated license plate reader (ALPR) is a camera paired with software that photographs every vehicle passing its field of view and extracts a record from each photo. A typical record includes:

• the license plate number;
• the camera's location;
• the date and time of the scan;
• a photograph of the vehicle; and
• often a "vehicle fingerprint": make, model, color, and identifying details such as roof racks, bumper stickers, or damage.

The scan happens for every car, all day, whether or not anyone is suspected of anything. The overwhelming majority of records describe vehicles that match no watch list at all - ordinary people, never accused of any crime, going about their lives.

Networks & Sharing

The Camera Is Local. The Database Is Not.

Modern ALPR products, including Flock Safety's, are sold as networks. Each scan is uploaded to a database hosted by the vendor, not kept in a filing cabinet at the local police department. Depending on contract settings, that database can be searched by:

• the agency that installed the camera;
• other agencies in the same network, sometimes across the country; and
• in some configurations, federal agencies or task forces.

This is the part most residents never hear at the council meeting: a camera approved to find stolen cars in one town can feed a nationwide, vendor-hosted search index. Who can query it, for what purpose, and with what audit trail is governed by contract language and policy - documents that are often not published until residents demand them.

Sharing settings, retention periods, and audit logging vary by jurisdiction and can change after the vote that approved the cameras. That is why our interim safeguards demand published contracts, policies, and audit logs.

The Aggregation Problem

Why the Sum Is the Danger

One scan is a moment. A network is a dossier.

A single scan is a small fact: one vehicle, at one place, at one moment. Standing alone it reveals almost nothing. The problem is what happens when thousands of scans from a networked system are combined - aggregated - and made searchable by plate number.

Query a plate across a network's history and the scans line up into a timeline. The timeline reveals patterns, and the patterns reveal a life:

• where a person works (the same block, every weekday morning);
• where they worship (the same address, every Sunday or Friday or Saturday);
• where they seek medical or mental health care (a clinic parking lot, repeatedly);
• which political events they attend, and where they assemble or protest;
• whose homes they visit, and when; and
• when and where they travel, and when their car is not at home.

Nobody decided to tell the government any of that. It falls out of the mathematics of collection. This is the same aggregation logic the Supreme Court confronted with cell-site records in Carpenter and location history in Chatrie - see Court Cases.

Glossary

Terms, Plainly Defined

ALPR (automated license plate reader)

A camera-plus-software system that photographs passing vehicles and extracts plate numbers and vehicle details into a searchable database record.

Hit

A scan that matches a watch list, such as a stolen-vehicle or wanted-person list. Hits are the tiny fraction of scans the systems are marketed on.

Non-hit data

Every other scan: records of vehicles matching no list at all - ordinary people, going about their lives. This is the bulk of every ALPR database, and its retention is the heart of the controversy.

Retention

How long scan data is stored before deletion. Every additional day of retention deepens the travel history that can be reconstructed. We ask that non-hit data be deleted within 48 hours or less.

Geofence warrant

A court order compelling a company to identify devices or accounts that were within a drawn area during a time window - searching outward from a place, rather than from a suspect. The Supreme Court's Chatrie decision (2026) held that acquiring Google Location History this way is a Fourth Amendment search.

Aggregate

To collect many small pieces of information into one larger whole. Each scan is minor on its own; aggregated, scans become a searchable record of a person's movements over weeks, months, or years.

Saying It Accurately

What the Law Does and Does Not Say

We hold ourselves to a legal accuracy rule: we never claim that "every ALPR is already unconstitutional." No court has held that. What the Supreme Court's aggregation cases establish is that assembling detailed location histories raises grave Fourth Amendment concerns and demands strict constitutional scrutiny. That is the accurate claim, it is fully sourced, and it is more than enough reason for a community to say no.

Case-by-case detail, with citations and official links: Court Cases.

The DeFlock Movement

See the Cameras. Map the Cameras.

Surveillance thrives on invisibility: most people have no idea a camera on a utility pole is logging their plate. The DeFlock movement answers that with transparency. DeFlock.org is a free, open-source, volunteer-built map of ALPR camera locations across the country, layered on OpenStreetMap data and grown by residents documenting cameras in their own towns. Locally, DeFlockOKC organizes the same work across the Oklahoma City metro.

You cannot debate a camera network you cannot see.

Use the map below: look up your own commute. Seeing how many times your plate is read on an ordinary Tuesday is the fastest way to understand the aggregation problem - and mapping is itself lawful, peaceful civic documentation: the cameras sit in plain view in public space, photographing you.

Map data: the volunteer-built DeFlock map (opens full-screen), built on OpenStreetMap. An embedded third-party map loads from deflock.org when this section is viewed; our own site still sets no cookies and runs no trackers.

Limiting your exposure, lawfully

Driving is public. You have no obligation to route your errands past surveillance cameras, and checking the map to choose streets without them is entirely lawful - like choosing not to walk through a metal detector you are free to walk around.

• Know your area. Check the map for camera placements on your regular routes; many cluster on main arterials and intersection chokepoints, and residential or secondary streets often have none.
• Add what you find. If you spot an unmapped camera, document it and submit it - the map only works because residents keep it current.
• Do not obscure your plate. Plate covers, sprays, flippers, and obstructions are illegal in Oklahoma and most states. This project does not endorse them, ever. The problem is not your plate; it is the network.

And the honest limit: individual avoidance is a stopgap, not a solution. You should not have to study a map to run errands unrecorded in a free country. The fix is not clever routing - it is removal. That is why this campaign exists.