What Data License Plate Readers Collect

A license plate reader doesn’t produce a single piece of evidence. It produces several kinds of records, created at different times by different parts of the system. Knowing which records exist is the first step in knowing which ones to ask for.

Data stored for every vehicle

The California State Auditor described the core record this way: software extracts the plate number from the image and stores it “with the date, time, and location of the scan and sometimes a partial image of the vehicle, in a searchable database.” Flock lists the data its cameras capture as:

The system stores this for every vehicle it reads, not just vehicles on a hotlist. The California State Auditor found that 99.9 percent of the 320 million images stored by the Los Angeles Police Department were of vehicles that were not on a hotlist when the image was taken.

Vehicle characteristics

Flock says its system can recognize “thousands of unique vehicle characteristics” and search full, partial and temporary plates. This means a vehicle can be found by its description, not only its plate number. It also means the system’s classification of a vehicle is a separate record that may be worth checking against the image itself.

Hotlist and alert records

When a plate read matches an entry on a hotlist, the system issues an alert. Flock says alerts can come from customer-defined hotlists or the FBI’s NCIC hotlist. The hotlist entry, the alert, and what happened after it (who received it, and whether anyone confirmed the match) are all separate pieces of information. See ALPR hotlists and alerts.

Search and audit logs

Stored ALPR data can be searched after the fact. Flock says every search is tied to a specific user and recorded in a log that supervisors can review, and that the stated reason for a search is recorded with it. Flock announced in August 2026 that officers will be required to enter a case code for every search by the end of 2026, and that an audit-assistance feature flagging unusual searches will become mandatory for law enforcement customers.

Audit practices haven’t always been strong. In its 2020 review of four California agencies, the State Auditor found the agencies had done little to no auditing or monitoring of ALPR use. See ALPR audit logs and search records.

How long the data is kept

Retention is set by the customer agency, and may also be limited by state law. Flock says data is permanently deleted at the end of the customer’s retention period unless it has been preserved as evidence. In August 2026, Flock lowered its recommended default from 30 days to seven. Agencies that already had an approved period kept it. Many agency policies published before that change describe a 30-day period.

The practical point: records that weren’t preserved may be gone within days or weeks. Whether and when records were preserved, and under what policy, can itself be relevant.

What vendors say isn’t collected

Flock states that its ALPR system doesn’t collect biometric data, driver information or facial recognition data, and that facial recognition is “Not included. Not planned.” Some agencies, however, add their own information. The California State Auditor found that two of the four agencies it reviewed added names, addresses, dates of birth and criminal charges to their ALPR systems.

What a record contains depends on the vendor, the system configuration and the agency’s practices. That’s why a defense attorney will usually want to see the records themselves. See requesting ALPR records in discovery.