Short answer
ALPR records usually come through discovery from the prosecution. In federal court, Rule 16 requires the government, on request, to allow inspection of data material to the defense or that it plans to use at trial, and Brady requires disclosure of favorable material evidence. Because ALPR data can be deleted within days, preservation requests should come early.
How the defense gets records
Discovery rules differ by jurisdiction. The federal rules show the main routes:
- Rule 16 discovery. On request, the government must permit the defense to inspect and copy “books, papers, documents, data, photographs” and other items in its possession, custody or control if they are material to preparing the defense, the government intends to use them in its case-in-chief at trial, or they were obtained from or belong to the defendant (Rule 16(a)(1)(E)).
- Brady disclosure. Suppressing evidence favorable to the accused that is material to guilt or punishment violates due process, “irrespective of the good faith or bad faith of the prosecution” (Brady v. Maryland, 1963).
- Subpoenas. Rule 17(c) allows a subpoena for “books, papers, documents, data, or other objects,” which the court can quash or modify if compliance would be “unreasonable or oppressive.”
State courts have their own discovery statutes and rules, which can be broader or narrower.
What to ask for
A request is more useful when it names specific records. Depending on the case, that can include:
| Record | Why it can matter |
|---|---|
| Full-resolution plate and vehicle images | Check the recorded plate text against what the camera actually captured |
| Read records: plate text, state, time, camera ID and location | Establish exactly when and where; check for clock or location errors |
| Alert record and hotlist entry | Source, entry date and status of the list entry on the day of the alert |
| Search and audit logs | Who searched, when, why and how broadly. See audit logs |
| Confirmation records | Dispatch audio, NCIC or database checks, and video showing whether the alert was verified |
| Agency ALPR policy and retention and sharing settings | The rules in force at the time; what was kept and who had access |
| Preservation records | Which reads were preserved, when, and by whom |
| Warrants and affidavits | How the ALPR data was described to a judge |
For what each record contains, see what data ALPR cameras collect.
Preservation: the first request
ALPR data is deleted automatically when the agency’s retention period ends. Flock’s recommended default is now seven days, and many agency policies written before that change set 30. Records not preserved as evidence may be gone. See data retention and sharing.
The law gives limited help after the fact. Under California v. Trombetta (1984), the constitutional duty to preserve covers evidence whose exculpatory value was “apparent before it was destroyed” and that the defendant couldn’t obtain by other reasonably available means. Under Arizona v. Youngblood (1988), losing merely “potentially useful evidence” violates due process only with bad faith. A prompt, specific preservation request makes it harder for records to disappear on a routine schedule.
Records held by others
ALPR data may be held by the investigating agency, another agency that shared it, or a vendor. Flock’s policy says customer data is owned by the customer and that Flock may disclose it “if legally required to do so” or to comply with legal process. Whether to seek records from the prosecution, another agency or a vendor, and by which procedure, depends on who has them and on local rules.
Limits and disputes
- Prosecutors may argue some records aren’t material or aren’t in their possession. Courts resolve these disputes, sometimes after a motion to compel.
- Requests that are too broad can be narrowed or quashed.
- Some states make ALPR data confidential for the public, which is a separate question from what a defendant can get in discovery. See public records requests for ALPR.
Discovery requests are made by your attorney. Questions to ask your attorney includes questions about records and preservation.
Law varies by state. State constitutions, statutes and courts may treat this issue differently from federal law. A licensed attorney in your jurisdiction can tell you how it applies.
Sources
- StatuteFederal Rules of Criminal Procedure, Rule 16, “Discovery and Inspection”Rule 16(a)(1)(E) · accessed 2026-11-05
- OpinionBrady v. Maryland373 U.S. 83 (1963)
- StatuteFederal Rules of Criminal Procedure, Rule 17, “Subpoena”Rule 17(c) · accessed 2026-11-05
- OpinionCalifornia v. Trombetta467 U.S. 479 (1984)
- OpinionArizona v. Youngblood488 U.S. 51 (1988)
- VendorFlock Safety, License Plate Reader Usage and Privacy Policy (audit logging, ownership and sharing sections)Last updated June 30, 2026 · accessed 2026-11-05
- VendorFlock Safety, “How Flock Protects” (data privacy and trust page)Accessed 2026-11-05
Related
- ALPR Audit Logs and Search RecordsWhat ALPR search and audit logs record (user, time, stated purpose, query terms), how agencies audit them, and why they can matter in a criminal case.
- ALPR Data Retention and SharingHow long license plate reader data is kept, who decides, how records are preserved, and how widely agencies share ALPR data, with Flock, Tennessee and California examples.
- Questions to Ask a Defense Attorney About ALPR EvidenceA printable checklist of 22 questions to ask a criminal defense attorney about Flock and license plate reader evidence: records, accuracy, the stop, identity and deadlines.
- What Data License Plate Readers CollectThe records an ALPR system like Flock creates: plate images and reads, vehicle characteristics, timestamps, locations, hotlist alerts, search logs, and how long they're kept.