Month: August 2026

Automated License Plate Readers and the Fourth Amendment

WRITTEN BY: Lieutenant Brian Tully (ret)

In January 2024, an officer in Gautier, Mississippi got an alert on his phone. A license plate reader at an intersection had captured a plate tied to Elijah Porter, who was wanted on an aggravated assault warrant. The officer ran the plate, located the vehicle, made the stop, and saw a Glock with a machinegun conversion switch protruding from under the driver’s seat. Porter moved to suppress all of it, arguing that using the LPR system to find his car was a violation of the Fourth Amendment and a warrantless search of his movements.

The Fifth Circuit disagreed in United States v. Porter, holding that the use of an LPR did not invade any reasonable expectation of privacy and therefore was not a search at all.

Seven weeks earlier, the City of Norfolk, Virginia won the same argument in a civil action where two Norfolk residents sued the city over its Flock ALPR program.  In this case, 176 cameras were the issue, not the ten in Gautier. But the judge who handed Norfolk that victory wrote a line every agency running ALPRs should read twice. Asked at what point ALPR surveillance becomes too intrusive to survive the Fourth Amendment, he answered “not today.”

A potentially ominous prediction by the court.

The Technology: What an ALPR System Actually Does

A fixed ALPR is a camera paired with software. It photographs passing vehicles, uses optical character recognition and machine learning to read the plate, and logs the plate number, date, time, and location to an encrypted, searchable database.

Three functions matter constitutionally.

• Real-time alerting: Each read is compared against hot lists for stolen vehicles, wanted persons, missing persons, and AMBER alerts. A match pushes an immediate notification with the date, time, and location of the hit, which is what happened in Porter.
• Retrospective query: Stored reads are searchable by full or partial plate. Some systems index make, type, color, and features such as roof racks and bumper stickers, so a vehicle can be searched without a plate number at all.
• Network sharing: Data can flow between agencies, and often well beyond the collecting department. This is the fastest growing piece of the technology and the least settled legally.

A fixed ALPR sees a vehicle only when that vehicle passes that camera. Norfolk deployed 176 cameras in 75 clusters across 66 square miles containing more than nine million feet of roadway. The district court described the system as having many thousands more blind spots than cameras. The reasoning behind the location of the cameras and the amount of uncovered road was important.

The Law

A person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another. A plate must be displayed where it sits in plain view from outside the vehicle, so there is no reasonable expectation of privacy in it.

RELATED ARTICLE BY BRIAN: Plain View in the Digital World

Carpenter v. United States was a major change to how law enforcement can obtain location information. Historical cell site location information was a search because it exposed the whole of the defendant’s physical movements. But the Court called the decision a narrow one and said it was not questioning conventional surveillance tools such as security cameras. 

Porter applied the distinction directly. The Gautier system provided only periodic information about a vehicle’s location as it passed one of ten fixed points. Unlike a cell phone, an LPR does not faithfully follow a person beyond public thoroughfares into residences, doctor’s offices, and other revealing locales.

Schmidt v. City of Norfolk stress tested the same principle. The plaintiffs’ vehicles were photographed roughly 475 and 325 times over four and a half months, placing them among the five percent of vehicles captured most often. The full plate matches averaged two to three per day, typically 2.5 to 3.5 miles apart with 45 to 50 minute gaps. The CSLI in Carpenter produced about 101 data points per day, thirty to fifty times that rate. The court granted summary judgment for the city, describing the fixed cameras as capturing images of locations rather than individuals.

Where This Is Heading: Density, Chatrie, and the Tipping Point

Schmidt is on appeal. It is pending in the Fourth Circuit as Schmidt v. City of Norfolk, No. 26-1227, fully briefed and drawing amicus filings from privacy organizations urging reversal and from a multistate brief supporting the city.

The Supreme Court decided Chatrie v. United States on June 29, 2026. The Court held that police conducted a Fourth Amendment search when they obtained a suspect’s Google Location History through a geofence request, because an individual has “a reasonable expectation of privacy in records about his cell phone’s location.” The Court declined to decide how narrowly a geofence warrant must be drawn and did not reach the exclusionary rule, remanding the case to the Fourth Circuit Court of Appeals for further arguments. 

Chatrie is not an ALPR case and the opinion does not mention license plate readers, but there are two important takeaways. Private custody of the data did not defeat the expectation of privacy. And the government could not escape the Fourth Amendment by noting it had pulled only a narrow, time-limited slice of a much larger database.

Each court upholding ALPR use has done so on the record in front of it, but as camera counts climb, retention lengthens, and networks interconnect across jurisdictions, the same analysis will eventually produce the opposite answer.  Judges are signaling that with the right facts an ALPR query could be a search requiring a Search Warrant. 

Practical Takeaways for Investigators

• Treat the hit as a lead, not as the conclusion: Porter survived because the officer corroborated. He ran the plate independently, confirmed the vehicle description and location, and connected it to an active warrant. Get your specific and articulable facts.
• Write the corroboration into the report, in sequence: The suppression hearing will be about what you knew before you activated the lights. Write it in your report.
• Log the query purpose: The audit report will be your friend in a suppression hearing.
• Watch cumulative query volume on a single vehicle: One query in one investigation is easy to defend. Repeated queries assembling weeks of movement on one plate is the fact pattern most likely to produce the first suppression ruling in this area.
• When in doubt, get the warrant: An application costs an hour. The courts could be moving the goal posts in the area of the law. 

Bottom Line

I don’t want your case to be the one that changes the precedent.  The judges in these cases are sending the law enforcement community signals.  They have told us exactly what will change the Fourth Amendment analysis: longer retention, broader sharing, and deeper integration with other data. Chatrie handed defense counsel a Supreme Court opinion holding that when it comes to location information neither third-party custody nor a narrow slice of a large database keeps the Fourth Amendment out of the analysis.

Be mindful of how you get and use ALPR data.

Plain View in a Digital World

“When can the police use evidence they stumble upon during a lawful search of a digital device?”

WRITTEN BY: Lieutenant Brian Tully (ret)

All police officers know the plain view doctrine. You are lawfully in a place, you see contraband, its criminal nature is obvious, and you can seize it. It’s the bag of pills on a passenger seat seen during a traffic stop.

What about plain view in a digital world? You have a warrant for drug evidence. The examiner is scrolling through a media folder. A video appears to have nothing to do with narcotics and everything to do with a felony nobody knew about. Is that plain view? Can you keep it? Can you start working the new case right then?

The US First Circuit Court of Appeals took up a version of that problem on May 18, 2026, in United States v. Deschambault. The ruling and the older Tenth Circuit case mentioned in the opinion together provide a practical guidance on how to handle the unexpected evidence in a digital world.

Plain View Defined

Plain view has three requirements:

First, lawful vantage point. The officer must be somewhere he is entitled to be. In a digital search, that means executing a valid warrant and looking in places the warrant allows.

Second, immediately apparent incriminating character. The evidentiary value must be obvious on its face, without further searching to establish it.

Third, lawful right of access. Seeing it is not enough. The officer must be able to get to it without another intrusion.

The Case

In August 2019, Maine drug agents arrested Rayevon Deschambault after a controlled buy. In the car they recovered two phones, a loaded handgun, a scale with cocaine residue, and packaging consistent with distribution. A state judge issued a warrant to search Deschambault’s iPhone for records tied to the trafficking, and for material showing who owned and used the device.

While executing that warrant, the agent found three videos. Two involved Deschambault and a female who looked young to the agent. The third had no sexual content and showed the same female standing in Deschambault’s bedroom, the identical room where officers had already recovered cash and drugs, with Deschambault panning the camera around and describing the room as a “dirty ass trap house room”.

The agent did not recognize the female. He circulated a clothed picture to other officers, one of whom identified her as a fourteen-year-old known from prior drug activity.  Investigators located her, interviewed her, and learned she knew Deschambault by his street alias, knew he and his girlfriend sold cocaine, and had been asked to help.

Then, and very importantly, they went back to a federal magistrate and obtained a second warrant authorizing a search of the phone for evidence of child exploitation. Deschambault was convicted on two counts of Sexual Exploitation of a Minor and sentenced to 216 months.

The Plain View Argument

Deschambault argued that once the agent noticed the female looked underage and began working to identify her, he had left the drug warrant behind and was investigating a different crime without authority.

The First Circuit disagreed, and the reasoning is important. The court did not need to rely on plain view because it found the videos fell inside the original warrant. The bedding, the wall paneling, and the background matched the room where drugs and cash were seized. Deschambault’s own recorded statements tied that room to distribution. The videos helped establish who had custody of the phone and connected him to the stash location.

The vantage point was lawful. The right of access was lawful. And the incriminating character was apparent without any further searching. All three tenets satisfied.

The court then addressed the juvenile’s identification effort separately and rejected the idea that following the lead was improper. Evidence lawfully seized under a warrant for one crime can be used to investigate another. Identifying the female was not abandoning the drug case, it was advancing it, and it produced a witness who could place Deschambault in the room with the narcotics. As a different federal case stated decades ago, when an investigation of one crime uncovers a trail to another, following that trail is the investigator’s job.

Where Digital Plain View Can Go Wrong

Deschambault leaned on US v. Carey, and the contrast between the two cases is the training point.

In Carey, a Tenth Circuit case from 1999, an officer had a warrant to search a computer for evidence of drug sales. He opened a file and found child pornography. At that moment he was squarely within plain view. Had he stopped, documented it, and applied for a second warrant, the analysis would have been straightforward.

He did not stop. He testified that he then spent roughly five hours opening additional image files, one after another, looking for more of the same. He was no longer searching for drug evidence. He was conducting a warrantless search for child pornography using a drug warrant as the entry ticket. Every file after the first one failed the lawful access requirement, because the warrant did not authorize a hunt for that material.

The First Circuit separated Deschambault from Carey on two grounds. The videos here were directly relevant to the drug investigation, which was not true in Carey. And the agent here did not convert his search into a child exploitation search without authority. He got the federal warrant first.

Takeaways

• Draft the affidavit so the categories requested are justified in your own words, based on your training and experience, and tied to the crime you are investigating.

• Putting the device under the control of your target is critical.  Like the investigators in Deschambault, add a category requesting evidence of care, custody, and control of the device.

• When something unexpected surfaces, document the moment. Note what you saw, when you saw it, and whether it connects to the crime in your warrant. If it does connect, say how.

• Do not exceed the scope of the warrant. The line between Deschambault and Carey is not what the investigator found. It is what he did in the ten minutes after he found it. One went back to a judge. One kept clicking.  Get the second warrant.

Register now for “Digital Evidence: Where to Find It and How to Use It” to learn how to avoid mistakes when dealing with digital evidence.