Flock cameras are automated license plate readers. They photograph passing vehicles, read the plate, and store the time and place of each read in a database that police can search later. Police departments in mid-Missouri use them, and plate reads now show up in the reports for ordinary state criminal cases.
The short answer to the question in the title: yes, in most situations police in Missouri can use these cameras without a warrant today. But the law is unsettled, Missouri put new limits on the technology in September 2026, and plate reader evidence has weak points that matter in a criminal case. Here is where things stand.
The technology
What do Flock cameras record, and how do police use them?
Police use plate readers in two different ways, and the difference matters legally.
Real-time alerts
A plate is placed on a “hot list” because it is tied to a stolen vehicle, a warrant, or an investigation. When a camera reads that plate, officers nearby get an alert with the location. The alert is often the reason for a traffic stop.
Searching past reads
An officer types in a plate, or a vehicle description, and gets back the places and times that vehicle passed a camera during the period the data was kept. Police use this to put a vehicle near a crime scene or to map where it has been.
Jefferson City and Columbia both operate Flock cameras, and agencies can share access with one another. A plate read in one city can end up in a case filed in Cole, Boone, or Callaway County.
The Fourth Amendment
Do police need a warrant to search Flock data?
Most courts so far have said no. One federal court recently said yes, and the question is on appeal in several places.
The starting point is an older rule. In United States v. Knotts (1983), the U.S. Supreme Court said a person driving on public roads has no reasonable expectation of privacy in the movements anyone could watch. A license plate is displayed to the public on purpose.
The Supreme Court has also said that rule has limits. In Carpenter v. United States (2018), it held that police conducted a search when they obtained a week of a person’s historical cell phone location records, because long-term location records reveal far more about a life than a single observation does.
Plate readers sit between those two cases, and courts are sorting out which one they resemble:
- Not a search. In United States v. Porter (March 17, 2026), the federal appeals court for the Fifth Circuit held that using a plate reader alert to find and stop a vehicle was not a search and required no warrant. The court reasoned that the system gave only periodic information about a vehicle on public roads.
- A search. On October 1, 2026, a federal trial judge in Oklahoma suppressed evidence in United States v. Kyle after an officer searched plate reader databases and pulled more than 50 sightings of one vehicle over about a month. The judge treated that as closer to the long-term tracking in Carpenter.
- Still pending. Other federal appeals courts have plate reader cases in front of them now.
None of those decisions binds a Missouri court. As of October 2026, we are not aware of a decision from the Missouri appellate courts or the federal Eighth Circuit that squarely answers the question. The pattern in the cases so far: a single alert leading to a stop is hard to challenge, and a search that reconstructs weeks of travel is where the argument is strongest.
Missouri rules
What limits does Missouri put on license plate readers?
The legislature has not passed a plate reader law. The current limits come from Executive Order 26-18, signed September 16, 2026.
- Who it covers. State agencies and local law enforcement agencies that receive state funding and use plate readers.
- 30-day deletion. Plate and vehicle images must be permanently deleted within 30 days of collection, unless the data is tied to a specific active criminal investigation or an active life-safety emergency, or a court orders it kept.
- Limited purposes. The systems may be used only for the administration of criminal justice and for lifesaving efforts.
- Every search is logged. Each search must record who ran it and either an active case number or a specific law enforcement reason.
- No facial recognition, and vendors may not sell or share data generated in Missouri.
- Misuse. Personal use or unauthorized sharing triggers discipline and, where appropriate, a criminal referral.
The order says its standards apply until the General Assembly passes permanent legislation, so expect this to change. The order is directed at agencies. It does not say that evidence is thrown out when an agency breaks its rules. Separately, the Missouri Constitution, Article I, Section 15, protects people in their “electronic communications and data” as well as their persons, papers, homes, and effects.
In a criminal case
How does plate reader evidence get challenged?
The constitutional question gets the attention. The practical questions are often more useful.
Was the alert right?
Cameras misread plates, and hot lists can be out of date. If a stop rested on an alert, the questions are what the alert said, whether the officer confirmed it before the stop, and whether the entry behind it was still valid.
Who was driving?
A plate read shows where a vehicle was. It does not show who was behind the wheel. In many cases the State needs other evidence to put a particular person in the car.
Who searched, and why?
Because searches are supposed to be logged with a user and a reason, the log itself is evidence. It can show when police first focused on a vehicle and what they knew at that point.
How much did they pull?
One sighting near a scene is different from a month of travel history. The more a search reconstructs a person’s movements, the stronger the argument that it needed a warrant.
In a Missouri state case, an unlawful search is raised by a written motion to suppress, filed before trial. Under RSMo 542.296, once the motion is filed the State has the burden of showing, by a preponderance of the evidence, that the motion should be overruled. The motion can rest on the Fourth Amendment and on Article I, Section 15 of the Missouri Constitution.
Answers
Plate reader questions we hear
Can police pull me over because a Flock camera flagged my plate?
Often, yes. An alert tied to a warrant, a stolen vehicle, or an investigation is commonly used as the reason for a stop. Whether a particular stop was lawful depends on what the alert said and whether it was accurate.
How long is Flock data kept in Missouri?
Executive Order 26-18 requires covered agencies to delete plate and vehicle images within 30 days, unless the data is tied to an active criminal investigation or life-safety emergency or a court orders it kept. Data that becomes evidence in a case is kept longer.
Does a plate read prove I was driving?
No. It shows a vehicle passed a camera at a certain time. Who was driving is a separate question the State has to prove with other evidence.
Can my lawyer find out who searched for my plate?
That is something to request in the criminal case. Missouri’s executive order requires each search to record the user and a case number or reason, so a record of the search should exist.
Police asked me where I was driving that night. Should I answer?
Talk to a lawyer first. Officers may already have plate reads and be comparing your answers against them. What you say can fill the gap the camera leaves, including who was driving.
Related: three things people say to police that prove the State’s case, how long police video lasts in Missouri, how a Missouri felony case works, and our constitutional rights page. We defend criminal cases in Cole, Boone, and Callaway Counties.
Talk to us
Find out how police found the car.
If you have been charged and a plate reader is part of the story, the records behind it have short retention periods. Raise it with your lawyer early.
Attorney advertising. The choice of a lawyer is an important decision and should not be based solely upon advertisements. This article is general information about Missouri law as of October 2026, not legal advice, and it does not create an attorney-client relationship. The law on license plate readers is changing, and whether evidence can be challenged depends on the specific facts.
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