Flock Safety and Automated License Plate Readers: Balancing Public Safety, Privacy, and the Fourth Amendment: Part Four – Traffic Stops Based on ALPR and Flock Alerts: When Does an Alert Create Reasonable Suspicion?
In the previous two articles, we examined the constitutional framework governing automated license plate reader (ALPR) technology and the manner in which lower courts have applied that framework to determine whether accessing historical ALPR or Flock Safety databases constitutes a Fourth Amendment search. As discussed, the Supreme Court has never directly addressed ALPR technology, leaving lower federal and state courts to apply the principles established in Katz v. United States, United States v. Knotts, United States v. Jones, and Carpenter v. United States. The overwhelming consensus emerging from those decisions is that querying historical ALPR databases generally does not constitute a Fourth Amendment search because the systems capture only discrete observations of vehicles traveling on public roads rather than the pervasive, continuous surveillance that concerned the Court in Carpenter.[1]
That conclusion, however, answers only part of the constitutional analysis. Determining that officers may lawfully access an ALPR database does not necessarily answer what they may do with the information once an alert is generated.
This article addresses a different—and far more practical—question.
When an ALPR or Flock camera generates an alert, may an officer immediately stop the vehicle?
For law enforcement officers, this question arises far more frequently than the database-search issue discussed in Article III. Every day, officers receive ALPR alerts indicating that a vehicle may be stolen, that its registered owner has an outstanding warrant, that the owner has a suspended or revoked driver’s license, or that investigators have entered the vehicle into a “hot list” as part of an ongoing criminal investigation. Officers must often decide within seconds whether the alert provides sufficient legal justification to initiate a traffic stop.
Unlike the constitutional issue addressed in Article III, the answer is generally not found in Carpenter. Instead, courts analyze these cases under the familiar principles governing investigative detentions established in Terry v. Ohio and its progeny. More recently, the Supreme Court’s decision in Kansas v. Glover has become particularly significant because it addresses the extent to which officers may rely upon information obtained from computerized law enforcement databases and the reasonable inferences that may be drawn from that information.[2]
The emerging body of ALPR stop cases demonstrates that courts do not view an electronic alert as a constitutional shortcut that automatically authorizes a traffic stop. At the same time, courts have repeatedly recognized that officers are entitled to rely upon reasonably trustworthy information contained in official law enforcement databases and to draw commonsense inferences from that information. Consequently, the constitutional question is not whether an ALPR alert exists, but whether, under the totality of the circumstances, that alert provides a particularized and objective basis for suspecting that criminal activity is occurring.
As with many Fourth Amendment questions, the answer depends upon the nature of the alert, the reliability of the underlying information, the observations made by the officer, and the reasonable inferences that may be drawn from the facts known at the time of the stop.
I. The Governing Fourth Amendment Standard
Although ALPR technology represents one of the most significant technological advancements in modern policing, the constitutional standard governing vehicle stops based upon ALPR alerts is not new. Courts have consistently analyzed these cases using longstanding Fourth Amendment principles governing investigative detentions rather than creating a separate constitutional framework for emerging technology.
The starting point, of course, is Terry v. Ohio. In Terry, the Supreme Court recognized that police officers may briefly detain an individual for investigative purposes when they possess reasonable suspicion, defined as “specific and articulable facts which, taken together with rational inferences from those facts, reasonably” lead an officer to believe criminal “may be afoot.“[3] Reasonable suspicion is a considerably lower standard than probable cause, but it requires more than an officer’s unparticularized suspicion or mere hunch. The Fourth Amendment instead requires objective facts that, when viewed collectively, justify the intrusion.
Over the decades following Terry, the Supreme Court repeatedly emphasized that reasonable suspicion is not subject to rigid rules or bright-line tests. Instead, courts must evaluate the totality of the circumstances known to the officer at the time of the stop. In United States v. Cortez, the Court explained that officers are entitled to draw inferences from objective facts based upon their training and experience and that courts should evaluate those facts collectively rather than in isolation.[4]
The analysis is necessarily practical, recognizing that officers frequently must make decisions in rapidly evolving circumstances based upon probabilities rather than certainties.
The Court reaffirmed that approach in United States v. Arvizu, cautioning lower courts against engaging in a “divide-and-conquer” analysis that examines each individual fact separately.[5] Conduct that appears entirely innocent when viewed in isolation may nevertheless contribute to reasonable suspicion when considered together with other circumstances. The Fourth Amendment therefore requires courts to examine the entire picture confronting the officer rather than discounting each fact one at a time.
Likewise, in Navarette v. California, the Court recognized that reasonable suspicion may be based upon information supplied by third parties, provided that the information bears sufficient indicia of reliability.[6] Although Navarette involved a 911 caller rather than an automated license plate reader, the decision underscores an important principle that frequently arises in ALPR cases: officers may rely upon information generated by sources other than their own personal observations if the information is sufficiently reliable to justify further investigation.
Perhaps the most significant Supreme Court decision for modern ALPR cases is Kansas v. Glover. Although Glover did not involve an automated license plate reader, its reasoning has become the analytical foundation for many ALPR-based traffic stops.
II. Kansas v. Glover and the Registered Owner Inference
Although Kansas v. Glover did not involve an automated license plate reader, it has quickly become the Supreme Court decision that most directly governs many ALPR- and Flock-based vehicle stops. Indeed, while Carpenter supplies much of the constitutional framework for determining whether accessing an ALPR database constitutes a Fourth Amendment search, Glover answers a different question: When may an officer rely upon information obtained from a law enforcement database to stop a vehicle? That distinction is critical because the constitutionality of most ALPR traffic stops turns not on the technology used to identify the vehicle, but on whether the information generated by the technology provides reasonable suspicion under Terry.
The facts of Glover were straightforward. A Kansas deputy sheriff ran the license plate of a pickup truck and learned through the state’s motor vehicle database that the registered owner’s driver’s license had been revoked. The deputy observed no traffic violation and possessed no information identifying the driver. Relying upon the commonsense inference that the registered owner was likely operating the vehicle, the deputy initiated a traffic stop. The Supreme Court held the following: absent information dispelling that inference, the stop was supported by reasonable suspicion and therefore complied with the Fourth Amendment.[7]
The Court emphasized several principles that have become central to ALPR litigation. First, reasonable suspicion is a practical, commonsense standard rather than a mathematical formula. Courts evaluate the probabilities confronting an officer in the field, recognizing that officers are permitted to draw reasonable inferences from objective facts.[8] Second, officers are not required to eliminate every innocent explanation before conducting an investigative stop. The Fourth Amendment requires only a particularized and objective basis for suspecting criminal activity, not proof beyond a reasonable doubt or even probable cause.[9]
Perhaps most importantly, Glover reaffirmed that officers may rely upon ordinary human experience when making investigative decisions. The Court concluded that it was entirely reasonable to infer that the registered owner of a vehicle was also its driver, even though that inference would not be correct in every case. The Fourth Amendment tolerates reasonable probabilities, not absolute certainty.[10]
That reasoning has proven especially significant in cases involving ALPR and Flock alerts. In many instances, the alert itself does not identify the driver. Instead, it identifies a vehicle associated with a registered owner who has an outstanding warrant, a suspended or revoked driver’s license, or another law enforcement database entry. Under Glover, the officer is ordinarily entitled to rely upon the commonsense inference that the registered owner is driving the vehicle unless other information dispels that inference.
Importantly, however, Glover does not stand for the proposition that officers may blindly rely upon every computerized database hit. The Court repeatedly emphasized that its holding was limited to situations in which officers possess no information that dispels the reasonable inference supporting the stop. If the officer observes facts indicating that the registered owner could not be the driver, for example, a significant difference in age or sex, the inference supporting reasonable suspicion may disappear.[11]
This distinction is particularly important in the ALPR context. An electronic alert is not itself the constitutional justification for the stop. Rather, it is one fact within the totality of the circumstances confronting the officer. The constitutional inquiry therefore remains the same one articulated in Terry, Cortez, Arvizu, Navarette, and Glover: considering everything the officer knew at the time, did the officer possess a particularized and objective basis for suspecting that the vehicle or its occupants were engaged in criminal activity?
As the cases discussed throughout this article demonstrate, courts have consistently answered that question by evaluating the reliability of the alert, the nature of the underlying database information, the officer’s corroborating observations, and any facts tending to confirm—or dispel—the reasonable inference of criminal activity. The presence of an ALPR or Flock alert is often an important part of that analysis, but it is rarely the entire analysis.
III. Alerts Based Upon Active Warrants, Stolen Vehicles, and Criminal Databases
One of the most common uses of Flock Safety cameras and traditional automated license plate reader (ALPR) systems is identifying vehicles associated with active arrest warrants, stolen vehicle reports, wanted persons, or other criminal justice databases. Unlike the constitutional issue discussed in the previous article—whether querying an ALPR database constitutes a Fourth Amendment search—these cases address a much more practical question: When an ALPR or Flock alert indicates that a vehicle is associated with criminal activity, does that alert provide reasonable suspicion to conduct an investigative stop?
The answer emerging from the cases is overwhelmingly yes.
Courts have consistently held that an ALPR alert tied to a reliable criminal justice database may provide reasonable suspicion to stop a vehicle, particularly where the officer verifies the license plate or vehicle and possesses no information dispelling the inference that the registered owner or wanted person is associated with the vehicle. Rather than treating ALPR technology as constitutionally unique, courts have viewed these alerts much like information received from dispatch, NCIC, GCIC, or other official law enforcement databases.[12]
Hernandez-Lopez v. State
One of the earliest appellate decisions addressing this issue is the Georgia Court of Appeals’ decision in Hernandez-Lopez v. State. A Gwinnett County deputy received an LPR alert indicating that the registered owner of a passing vehicle was wanted for failure to appear in court. After confirming that the vehicle matched the alert and observing that it was being driven by an adult male consistent with the available information, the deputy conducted a traffic stop.[13]
The court held that the stop was supported by reasonable suspicion. In doing so, it rejected the argument that ALPR technology required a special evidentiary foundation, explaining that the system merely automated what officers had long done manually—checking license plates against criminal justice databases. The court further likened the LPR hit to information obtained through GCIC, concluding that officers may reasonably rely upon official database information when initiating an investigative stop.[14]
Although Hernandez-Lopez predates the Supreme Court’s ruling in Kansas v. Glover, the analytical similarity is striking. In both cases, officers relied upon an official law enforcement database, matched the vehicle encountered on the roadway with the database information, and acted in the absence of facts suggesting the driver was someone other than the registered owner. Glover later confirmed that this type of commonsense inference ordinarily satisfies the reasonable suspicion standard.
United States v. Lurry
A federal district court reached the same conclusion in United States v. Lurry. A Memphis officer received an ALPR alert identifying a vehicle associated with an outstanding warrant, confirmed that the driver matched the limited description available, and conducted a traffic stop that ultimately resulted in the recovery of a firearm. The court upheld the stop, finding that the officer reasonably relied upon the warrant information while corroborating the alert through his own observations before taking enforcement action.[15]
United States v. Porter
The Fifth Circuit likewise upheld a stop based upon an LPR alert in United States v. Porter. After receiving an alert that a vehicle was associated with an outstanding aggravated assault warrant, the officer contacted dispatch and was told the vehicle was associated with “Elijah Porter, and confirmed the vehicle information through the department’s computer system, which showed the vehicle was associated with “James Stewart” or “E.L. Porter.” The officer did not have a physical description of Porter. The officer initiated a stop. The court held that the alert provided reasonable suspicion even though the officer lacked a physical description of the driver, emphasizing that officers may rely upon official criminal justice databases and the collective knowledge doctrine in making investigative decisions.[16] The Fifth Circuit specifically stated that the stop was valid based on the following:
First, Officer Hoggard, had reasonable suspicion to initiate the traffic stop based solely on the automatic license plate reader, or the ALPR, hit that revealed an outstanding arrest warrant for Mr. Porter; Number 2, the [“be on the lookout”] BOLO [report], or ALPR, hit does not need to include a physical description of the driver to provide an officer reasonable suspicion to initiate a traffic stop; and number 3, under the collective knowledge doctrine, the ALPR was reliable and provided Officer Hoggard with reasonable suspicion to initiate the traffic stop.[17]
Significantly, the Fifth Circuit also emphasized that officers are entitled to rely upon information communicated through official law enforcement systems under the collective knowledge doctrine and need not independently verify every fact contained within those databases before acting.[18]
Traft v. Commonwealth
The Kentucky Supreme Court reached the same practical conclusion in Traft v. Commonwealth.[19] In Traft, an officer received an LPR alert that Traft, the registered owner of a vehicle that had just passed the officer, was wanted under an active warrant for failure to appear. The officer conducted a traffic stop on the vehicle. It was discovered upon approaching the vehicle Traft was driving the vehicle and he was under the influence of alcohol. He was arrested after an investigation.
Traft later argued that the stop of his vehicle was unlawful because it based solely on an LPR alert that he was wanted for failure to appear. Traft noted that the officer took no investigative steps to determine who was driving the vehicle prior to conduct the traffic stop. The Supreme Court of Kentucky held:
While it is true that Schepis did not know the identity of the driver when he initiated the stop, we hold that the fact that the owner of the vehicle was subject to seizure for violation of law creates an articulable and reasonable suspicion for an officer to initiate a traffic stop.[20]
Thus, the court held that the LPR alert provided reasonable suspicion of criminal activity based upon the alert of the active warrant and as such, the stop was lawful.
What These Cases Mean for ALPR Alerts
Although the facts differ, these decisions reflect a remarkably consistent approach. None of the courts viewed an ALPR or Flock alert as creating a new constitutional rule. Instead, they treated the technology as another method of delivering information already contained in official criminal justice databases.
Three common principles emerge.
First, an alert tied to an active warrant, stolen vehicle, or other criminal justice database generally provides reasonable suspicion to justify an investigative stop.
Second, officers strengthen the constitutional basis for the stop by confirming readily available information, such as the license plate, vehicle description, or other identifying characteristics, before activating their emergency equipment.
Third, the constitutional analysis remains governed by the totality of the circumstances. Courts evaluate the alert together with the officer’s observations, the reliability of the underlying database, and the absence of facts suggesting that the information is inaccurate or that the reasonable inference of criminal activity has been dispelled.
For agencies using Flock Safety cameras, the lesson is straightforward. Courts overwhelmingly treat properly generated alerts tied to active criminal justice databases as sufficient to establish reasonable suspicion, as long as there is no information indicating that the alert is erroneous.
Viewed together, these decisions demonstrate the practical significance of Glover. Whether the information originates from a dispatcher, a routine computer inquiry, an NCIC or GCIC database, or an ALPR or Flock alert, the constitutional analysis remains the same. Courts ask whether the officer possessed objective facts that would lead a reasonable officer to suspect that the driver or occupant was connected to criminal activity. When an ALPR alert identifies a vehicle associated with an outstanding warrant or other valid criminal database entry, and the officer possesses no information negating the reasonable inference that the registered owner is driving, Glover strongly supports the constitutionality of the ensuing stop.
At the same time, Glover also establishes important limits. The Court repeatedly emphasized that its holding applies only when the officer lacks information negating the inference that the registered owner is operating the vehicle. For example, if the officer observes that the driver is plainly of a different sex, substantially different age, or otherwise inconsistent with the registered owner’s description, the reasonable inference supporting the stop may disappear.[21]
Accordingly, Glover should not be read as authorizing traffic stops based upon every automated alert. Rather, it confirms that officers may rely upon reasonable, commonsense inferences drawn from reliable law enforcement databases while continuing to evaluate the totality of the circumstances confronting them. That balance between technological efficiency and individualized suspicion has become the governing framework for modern ALPR and Flock stop cases.
IV. Garbage In, Garbage Out: What if a database is known to be unreliable?
In contrast to principle in Glover, if an officer possesses information suggesting that the underlying database entry is inaccurate or stale, reasonable suspicion to justify the stop may not be present.
An example of this principle is found in the Tenth Circuit’s decision in United States v. Esquivel-Rios. Judge Gorsuch began the opinion with a memorable observation that resonates well beyond the facts of that particular case: “Garbage in, garbage out.”[22] In Esquivel-Rios, a Kansas trooper stopped a driver because the Colorado temporary registration tag displayed on his vehicle returned “not on file” when the trooper conducted a tag check through dispatch. The dispatcher also told the trooper, “Colorado temp tags usually don’t return.”[23] The trooper conducted a traffic stop believing the tag may be fraudulent and subsequently received consent to search. The trooper located a pound of methamphetamine. On appeal, Esquivel-Rios argued that the stop of his vehicle was unlawful because he, in fact, had a valid temporary tag displayed on his vehicle. The Tenth Circuit Court of Appeals noted that the reasonable suspicion required to stop a vehicle is “’considerably less’ than a preponderance of the evidence and ‘obviously less’ than that required for probable cause to effect an arrest.”[24] The court also noted that the officer is not required to rule out possible innocent conduct to obtain reasonable suspicion.[25] The court then noted that there was insufficient evidence in the record to determine if Colorado’s temporary tag database was sufficiently reliable for a “not on file” response to amount to reasonable suspicion of criminal activity, therefore the case was remanded back to the district court for such determination.
Whether reliance is reasonable depends upon the circumstances confronting the officer. If an ALPR alert identifies a vehicle associated with an active arrest warrant, a stolen vehicle report, or another reliable criminal justice database, and the officer observes nothing suggesting the information is inaccurate, courts have generally upheld the resulting stop. Conversely, when readily available information casts doubt upon the accuracy of the alert, or when the database itself appears unreliable, courts have been unwilling to allow technology to substitute for individualized constitutional judgment.
The lesson for law enforcement officers is straightforward. ALPR and Flock systems are extraordinarily valuable investigative tools, but they remain investigative tools—not constitutional decision makers. Officers should trust reliable database information, but they should also verify what they reasonably can before initiating a stop. Confirm the license plate. Confirm the vehicle description if available. Review the reason for the alert. If possible, consider whether the driver appears consistent with the available information. Be cognizant of facts that either strengthen or weaken the inference that criminal activity is occurring. Those few additional observations often make the difference between reasonable reliance upon technology and unconstitutional reliance upon an erroneous computer alert.
As courts continue to evaluate ALPR technology, one principle has emerged with remarkable consistency: the Fourth Amendment does not require perfection from police officers, but it does require reasonableness. That standard applies just as forcefully to computerized information as it does to every other aspect of a criminal investigation.
V. When an Alert Alone May Not Be Enough
Although the overwhelming majority of reported decisions have upheld vehicle stops based upon ALPR alerts tied to active warrants, stolen vehicles, or other reliable law enforcement databases, those decisions should not be interpreted as establishing a bright-line rule that every electronic alert automatically creates reasonable suspicion. To the contrary, courts have consistently recognized that an ALPR alert is only one fact, albeit a substantial fact, within the totality of the circumstances. Like any other source of information, its constitutional significance depends upon its reliability, the officer’s ability to corroborate the information, and whether other known facts strengthen—or undermine—the inference that criminal activity is occurring.
Courts have expressed concern about stale or inaccurate database information, unreliable data sources, and circumstances in which officers possess information that contradicts the inference generated by the computerized alert. These cases serve as an important reminder that while technology has become an indispensable investigative tool, it has not displaced the officer’s constitutional obligation to exercise independent judgment.
Perhaps the most instructive decision is the Tenth Circuit’s opinion in United States v. Esquivel-Rios. Although the case did not involve an ALPR alert, its reasoning applies with equal force to every computerized law enforcement database. Judge Gorsuch framed the issue in practical terms by observing that computers merely process the information they are given—”garbage in, garbage out.”[26] If inaccurate information is entered into a database, or if no information is entered into the database, the resulting alert will be equally inaccurate. Consequently, the constitutional question is not whether a computer generated an alert, but whether the underlying information was sufficiently reliable to support reasonable suspicion.
The court recognized that modern policing increasingly depends upon computerized records. Patrol officers routinely rely upon information generated by NCIC, state motor vehicle databases, warrant files, criminal history repositories, and ALPR systems. Generally, an officer may rely upon such computer databases, unless there is a known reason that calls that reliability into question. But that reliance presupposes that the information itself is reasonably trustworthy. As the court recognized, the Fourth Amendment does not permit the government to substitute an unreliable computer record for individualized suspicion.
The same concern arises when database information becomes stale. A warrant may have been recalled but not removed from the database. A vehicle may have been recovered after being reported stolen. A registration record may not reflect a recent transfer of ownership. An investigative “hot list” entry may remain active long after investigators have lost interest in the vehicle. In each of these situations, the computer faithfully reports information that may no longer be accurate.
Courts therefore continue to evaluate not simply whether an alert existed, but whether the officer’s reliance upon that alert remained objectively reasonable under the circumstances. If officers possess information suggesting that a database entry is outdated or inaccurate—or if readily available facts call the alert into question—additional corroboration may be necessary before initiating a stop.
Likewise, reasonable suspicion may disappear when the officer observes facts that negate the very inference supporting the stop. This principle is not unique to ALPR technology; it follows directly from the Supreme Court’s decision in Kansas v. Glover. There, the Court emphasized that officers may rely upon the commonsense inference that the registered owner is driving the vehicle only so long as nothing dispels that inference. If an officer knows that the registered owner is a seventy-year-old male but observes that the driver is a young female, the inference underlying the stop no longer exists. The same principle applies when other objective facts contradict the information supplied by an ALPR alert.[27]
The same reasoning applies when officers are unable to corroborate information that is reasonably capable of confirmation. An ALPR alert indicating that a wanted individual is associated with a particular vehicle may justify further observation, but if the officer quickly determines that the driver plainly does not match the wanted person’s age, sex, or other readily observable characteristics, the justification for the stop may evaporate. Likewise, if the vehicle’s license plate, make, or model does not match the information contained in the alert, the officer should pause before relying exclusively upon the computerized information.
If the alert is generated from a reliable database, the information is current, the officer confirms the readily observable facts, and nothing contradicts the inference of criminal activity, courts have generally upheld the stop. Conversely, when the underlying information is stale, the database appears unreliable, the officer cannot corroborate readily available information, or objective facts negate the inference supporting the alert, reasonable suspicion may no longer be present.
VI. Not All ALPR Alerts Provide the Same Legal Authority
Some ALPRs allow officers to create “hot-lists” for investigatory purposes. For example, an officer may have developed a person of interest in a series of thefts, even though there is insufficient evidence to support a stop or arrest. This list would alert officers if the person of interested passed an ALPR camera in that area so that the officer can be on the lookout to determine if the person is or is not the person committing the thefts. This type of alert typically does not provide sufficient reasonable suspicion to justify a stop. A stop would be justified on this type of alert only if the officer that entered the alert had sufficient reasonable suspicion and the information was not stale; this is the collective knowledge doctrine. Otherwise, an officer would need some other information or the observation of a traffic violation to establish justification for a stop.[28]
In contrast, an alert generated from an active arrest warrant, a stolen vehicle report, or some other crime carries considerably greater constitutional weight than an informational alert entered merely to locate a vehicle as part of an ongoing investigation. This distinction is particularly important because officers sometimes refer to all ALPR notifications as “hits,” when in reality the legal significance of the alert depends upon the reason the vehicle appears in the database. A stolen vehicle alert, an active warrant, or a suspended-license notification generally carries with it an objective basis for suspecting criminal activity. A “locate vehicle” entry, standing alone, may not.
VII. Conclusion
The legal principles governing vehicle stops based upon ALPR alerts are becoming increasingly clear. Courts have consistently recognized that ALPR and Flock systems are powerful investigative tools, but they are not constitutional shortcuts. An electronic alert does not, by itself, replace the Fourth Amendment’s requirement of reasonable suspicion. Rather, it represents one fact, which is very substantial, within the totality of the circumstances confronting the officer.
When an alert is generated from a reliable criminal justice database, identifies criminal activity such as an active warrant or stolen vehicle, the officer verifies the available information, and no objective facts dispel the reasonable inference of wrongdoing, courts have generally upheld the resulting stop. Decisions such as Kansas v. Glover, Hernandez-Lopez, Traft, Porter, and Lurry collectively demonstrate that officers may rely upon official law enforcement databases and commonsense inferences when making investigative decisions.[29]
The converse is equally true. When officers rely upon stale, inaccurate, or inadequately verified database information—or when objective facts undermine the inference supporting the alert—the constitutional analysis changes. Cases such as Esquivel-Rios remind us that computers are extraordinarily efficient, but they are not infallible. Bad information entered into a database remains bad information no matter how sophisticated the technology used to retrieve it.[30]
For law enforcement officers, the practical lesson is straightforward. Trust the technology—but verify it as well. Confirm the information that is reasonably capable of confirmation. Understand why the alert was generated. Consider facts that either strengthen or weaken the inference of criminal activity. Document what the system displayed and what you personally observed. Those simple steps not only produce better investigations, but they also produce stronger constitutional cases. Additionally, if an officer observes a traffic violation prior to conducting a traffic stop based on an ALPR alert, he or she should document that violation as an independent basis for the stop.[31]
As courts continue to evaluate ALPR and Flock technology, one principle appears firmly established: the Constitution welcomes technological innovation, but it continues to require individualized, objective, and reasonable police judgment.
______________________________________________
[1] Katz v. United States, 389 U.S. 347 (1967); United States v. Knotts, 460 U.S. 276 (1983); United States v. Jones, 565 U.S. 400 (2012); Carpenter v. United States, 585 U.S. 296, 138 S. Ct. 2206 (2018); see also United States v. Martin, 753 F. Supp. 3d 454 (E.D. Va. 2024); Robinson v. Commonwealth, 87 Va. App. 262, 927 S.E.2d 822 (2026); United States v. Porter, 170 F.4th 381 (5th Cir. 2026).
[2] Kansas v. Glover, 589 U.S. 376 (2020)
[3] Terry v. Ohio, 392 U.S. 1, 21, 30 (1968)
[4] United States v. Cortez, 449 U.S. 411, 417–419 (1981)
[5] United States v. Arvizu, 534 U.S. 266, 274–275 (2002)
[6] Navarette v. California, 572 U.S. 393 (2014)
[7] Kansas v. Glover, 589 U.S. 376, 378 (2020)
[8] Id. at 381–84
[9] Id.
[10] Id. at 384-386
[11] Id. at 385–86
[12] Kansas v. Glover, 589 U.S. 376 (2020)
[13] Hernandez-Lopez v. State, 319 Ga. App. 662 (2013)
[14] Id. at 664-665
[15] United States v. Lurry, No. 2:09-cr-20312, 2010 U.S. Dist. LEXIS 118494 (W.D. Tenn. Nov. 8, 2010)
[16] United States v. Porter, 170 F.4th 381 (5th Cir. 2026)
[17] Id. at 385
[18] Id.
[19] Traft v. Commonwealth, 539 S.W.3d 647 (Ky. 2018)
[20] Id. at 651
[21] Glover, 589 U.S. at 385–86
[22] United States v. Esquivel-Rios, 725 F.3d 1231, 1237 (10th Cir. 2013)
[23] Id. at 1235
[24] Id. at 1236
[25] Id.
[26] United States v. Esquivel-Rios, 725 F.3d 1231, 1237 (10th Cir. 2013)
[27] Kansas v. Glover, 589 U.S. 376, 385–86 (2020).
[28] Whren v. United States, 517 U.S. 806 (1996) (traffic stop lawful if the officer observes a traffic violation even if there is an ulterior motive for the stop).
[29] Kansas v. Glover, 589 U.S. 376 (2020); Hernandez-Lopez v. State, 319 Ga. App. 662, 738 S.E.2d 116 (2013); Traft v. Commonwealth, 539 S.W.3d 647 (Ky. 2018); United States v. Porter, 170 F.4th 381 (5th Cir. 2026); United States v. Lurry, No. 2:09-cr-20312, 2010 U.S. Dist. LEXIS 118494 (W.D. Tenn. Nov. 8, 2010)
[30] United States v. Esquivel-Rios, 725 F.3d 1231 (10th Cir. 2013)
[31] Whren v. United States, 517 U.S. 806 (1996) (traffic stop lawful if the officer observes a traffic violation even if there is an ulterior motive for the stop).
