The United States Court of Appeals for the Fifth Circuit recently released an opinion in United States v. Porter, a case that considers whether the government’s use of historical location information from a networked license plate reader system, constitutes a search under the Fourth Amendment, and whether a traffic stop and seizure arising from data obtained from a license plate reader is lawful.
Summary of the Facts
Elijah Porter was a wanted individual in Mississippi who had an outstanding warrant for aggravated assault. In January 2024, a license plate reader “ALPR” system at a specific intersection captured a license plate of a vehicle associated with criminal activity. Charles Hoggard, a former Gautier Police Department Lieutenant, was alerted. Dispatch informed him that the vehicle was associated with Porter and informed him of the warrant. After locating the vehicle, Lieutenant Hoggard initiated a traffic stop. Once he identified Porter as the driver, Porter was detained and pat down. Lieutenant Hoggard then saw a firearm, which he believed to be an automatic Glock, sticking out from under the driver’s seat. He then asked Porter whether there were any weapons in the car, and Porter answered in the negative. Before Lieutenant Hoggard confirmed that “the warrant was valid and true,” he retrieved the Glock and a machinegun conversion switch during an inventory search of the vehicle. After securing the firearm in his patrol car, he confirmed the warrant and took Porter to the police station. Subsequently, Porter was charged with possession of a machinegun.
Before trial, Porter moved to suppress both the ALPR data that was used to locate his vehicle and the recovered firearm from the stop. He argued that the extensive collection and querying of license plate reader data amounted to a Fourth Amendment search since it allowed the government to reconstruct his movements over time without a warrant. He also argued that the stop was not supported by adequate suspicion; therefore, the firearm was the fruit of an unconstitutional search and seizure. Ultimately, the district court denied the suppression motion and held that Porter did not have a reasonable expectation of privacy in his vehicle’s license plate or its movement on public roads, and that use of ALPR data, therefore, did not constitute a search under the Fourth Amendment. The court further concluded that the officers had at least reasonable suspicion to stop the vehicle because they were acting on an outstanding warrant and used information obtained from their first-hand observations, and that the subsequent discovery of the firearm resulted from lawful investigative steps during the stop. Porter was ultimately convicted of the firearm offense and sentenced. As a result, he appealed, seeking review by the United States Court of Appeals for the Fifth Circuit.
United States Court of Appeals for the Fifth Circuit
The United States Court of Appeals for the Fifth Circuit affirmed the district court’s rulings and ultimately affirmed the conviction. The Court held that the use of the LPR system to identify Porter’s vehicle did not violate the Fourth Amendment because there was no reasonable expectation of privacy in movements on public roads or in license plate information. Using a comparator, the Court explained that the LPR data is not as comprehensive as cell-site location data. The Court further held that the traffic stop was supported by reasonable suspicion and found that the firearm recovered during the stop was lawfully seized under the plain view doctrine.
The Fifth Circuit first addressed whether the use of a license plate reader system violated a reasonable expectation of privacy, constituting a warrantless search in violation of the Fourth Amendment. On appeal, Porter alleged that the collection and querying of data allowed the government to obtain a detailed record of where he had been and when he was there, similar to the cell-site location records that required a warrant in Carpenter v. United States. The court cited past precedent from United States v. Smith, which held that when government actors intrude a place where an individual has a reasonable expectation of privacy is generally held to be a search that requires a warrant supported by probable cause. The court emphasized that Supreme Court precedent has held that while a person in public generally does not have a reasonable expectation of privacy, they “do not surrender all Fourth Amendment protection by venturing into a public sphere.” The court also cited the Supreme Court’s ruling in United States v. Knotts, which held that “a person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another.”
The court explained that in this case, Porter was required by law to display his license plate and could be seen by anyone who looked at him driving on public roads. Further, the ALPR system only scans a vehicle’s location on public streets and highways when a vehicle passes a location where a camera is stationed. Distinguishing this case from the seminal decision in Carpenter, the Fifth Circuit explained that in Carpenter, the Supreme Court held when the Government obtains access to historical cell-phone records that provide a chronicle of the user’s past movements, it constitutes a search under the Fourth Amendment. The Fifth Circuit explained that cell-site location information involves continuous, involuntary signaling through a private device, distinguishable from ALPR data because license plate readers capture sporadic images of a vehicle’s publicly displayed plate as it travels on public roads. Therefore, the court concluded that the historical, collected ALPR data used by Lieutenant Hoggard did not reveal the sort of comprehensive, intimate view of a person’s life that Carpenter found to be constitutionally relevant. As a result, the querying of the ALPR database for hits on Porter’s vehicle did not constitute a Fourth Amendment search.
Additionally, the Court considered Porter’s argument that the traffic stop was not supported by reasonable suspicion or probable cause and that evidence from the subsequent stop should be suppressed. Beginning with its analysis on the validity of the stop, the Court emphasized that under United States v. Hensley, the Supreme Court held, “If police have reasonable suspicion, grounded in specific and articulable facts, that a person they encounter was involved in or is wanted in connection with a completed felony, then a Terry stop may be made to investigate that suspicion.” Applying that principle to the facts of this case, the Circuit explained that Lieutenant Hoggard had an outstanding warrant and used the license plate reader system to identify likely locations where the Porter’s associated vehicle would appear. He then later observed a car that matched the plate and description. When Lieutenant Hoggard confirmed the plate through an in-car computer check, he realized that it was associated with a wanted individual. As such, the Circuit found that the officer had reasonable suspicion to conduct a Terry stop at minimum and probable cause to arrest Porter based on the warrant itself.
The Court then turned to analyzing the search that led to the discovery of the firearm. In doing so, the Court relied on the Plain View Doctrine, which allows officers to seize evidence in plain view, provided that they have not violated the Fourth Amendment in arriving at the spot from which the observation of the evidence is made and have probable cause to believe that the item is contraband or evidence of a crime. Here, Lieutenant Hoggard testified “that the barrel was sticking out from under the seat” in plain view. Relying on evidence obtained from the officer’s body-worn camera footage, the Court explained that the footage shows Lieutenant Hoggard physically removing the firearm from under the driver’s seat in seamless, “quick darting motion.” The court found that this suggested that he knew precisely where the Glock and the switch were after previously seeing them in plain view. Thus, the Fifth Circuit found that the firearm and switch were lawfully seized under the plain view doctrine.
Key Takeaways
In Porter, the Fifth Circuit ultimately issued the following holdings: (1) Officer’s use of location data obtained from license plate reader (LPR) system to identify vehicle associated with criminal activity did not violate Fourth Amendment; (2) officer had reasonable suspicion to stop defendant’s vehicle; and (3) gun and automatic conversion switch came within “plain view” exception to warrant requirement.
Porter emphasizes that LPR data may be used to help locate a vehicle associated with a wanted suspect when the data captures a vehicle’s license plate on a public road. The Fifth Circuit held that the LPR query in this case was not a Fourth Amendment search because it captured intermittent public-road location information, not continues tracking comparable to cell-site location data. As illustrated in this case, LPR data may be used as an investigative lead to help officers identify and locate a vehicle associated with criminal activity. However, law enforcement must not treat an LPR hit as a shortcut around the Fourth Amendment, ensuring that officers establish specific facts supporting a lawful stop.
United States v. Porter, 170 F.4th 381 (5th Cir. 2026)