An Oklahoma federal judge’s decision to throw out automatic license plate recognition (ALPR) evidence in a meth trafficking case last week is the most significant example to date of how a recent Supreme Court decision on geofencing will weigh on digital evidence and Fourth Amendment court proceedings moving forward, experts say.

Judge Sara Hill ruled October 1 that an arresting officer improperly used data from Flock brand ALPRs to build a case against Melisa Kyle — a decision heavily informed by the landmark June geofencing ruling, known as Chatrie, in which a majority of justices found that police searches of historical cell phone locations provided by third-party tech companies are limited by the Fourth Amendment.

Hill’s ruling that Flock searches are “approaching dragnet-type law enforcement practice” — and can be unconstitutional when conducted without a warrant — is a landmark finding on its own and, as with Chatrie, will influence judges considering future cases involving ALPR data, experts said.

The decision is one of the first times a federal judge has determined law enforcement searches for historic ALPR-collected data can violate the Fourth Amendment.

The Oklahoma decision does not set a binding precedent but is significant because it breaks from a consistent pattern of courts ruling that ALPR searches conducted without a warrant are acceptable under the Fourth Amendment since they don’t track everywhere a person goes minute by minute.  

Hill cited the June high court decision repeatedly in her opinion holding that officers need a warrant for some ALPR searches due to the fact that they capture citizens’ locations on a regular basis and are retroactively available to law enforcement.

In the Oklahoma case, a sheriff’s deputy stopped Kyle primarily because she had a California plate. He subsequently searched Flock to access an extended history of Kyle’s vehicle’s whereabouts, constituting what Hill called an “unconstitutional warrantless search” and an example of “indiscriminate mass surveillance.”

The arresting officer used Flock to quickly find 50 separate instances of Kyle’s car traveling in multiple states across a month-long period, according to Hill’s ruling. The Flock search was accessed without probable cause and violated Kyle’s constitutional rights, the opinion said, rendering the evidence found in a subsequent search of her vehicle inadmissible.

The June case, Chatrie v. United States, focused on how geofencing sweeps up cell phone location data histories for large numbers of innocent people, typically when law enforcement lacks a suspect and asks tech companies for digital location histories of everyone in the area of a crime.  

Time matters

For many years, judges have consistently ruled that scanning license plates and aggregating that location data does not require a warrant because individuals have no reasonable right to privacy if they are traveling on public roads. But citing Chatrie, Hill said that ALPR data searches are unconstitutional when used to track people over an extended period of time — even when they are on public roads.

“Cell phones also move in public places where people can see you in plain view,” Hill’s opinion said. 

ALPRs become “constitutionally problematic when law enforcement can indiscriminately and passively catalog your whereabouts over an extended period of time and then use that information for any purpose whenever convenient,” Hill wrote.

Oklahoma authorities have not yet said whether they plan to appeal the decision.

The Oklahoma case’s parallels to Chatrie are unmistakable, say legal scholars, defense lawyers and privacy advocates. They predicted many more digital surveillance decisions influenced by the Supreme Court case. 

“This case is a direct result of Chatrie and the Supreme Court signaling that it takes location data searches seriously,” Andrew Ferguson, the author of "Your Data Will Be Used Against You" and a professor at George Washington Law School, said via email about the Oklahoma ruling.

Hill “chose to view ALPRs as a tracking system that can capture the whole of one’s movements and not just a fancy camera that catches numbers and letters,” he added.

It is also the first time a court has said ALPR searches require a warrant in some circumstances, according to Ferguson.

In August, a Mississippi federal judge also cited Chatrie when he ruled that cell tower dumps are unconstitutional general warrants under the Fourth Amendment. Such warrants give law enforcement sweeping authority to search people and places without naming suspects.

Data provided to police ‘on demand’

In May 2026, Freddie Alaniz, a Tulsa County deputy sheriff, saw Kyle’s car change lanes without signaling. Because she had a California plate, Alaniz searched Flock’s national database, finding Kyle had traveled extensively over the past month. He then pulled Kyle over, further searched Flock, asked Kyle probing questions about her location history based on the ALPR sightings and then tossed her car, finding a large quantity of methamphetamine.

Alaniz’s decision to physically search Kyle’s car — primarily based on the detailed Flock information drawn from the surveillance firm’s network-connected camera system and vast national database — was improper, Hill said.

ALPR searches are “not targeted on a single individual,” Hill’s decision said. “It is a tool that collects information about all vehicles that pass by any network-connected camera at all times, and it serves up the information to law enforcement on demand.”

While Hill acknowledged that Flock cameras do not reveal individuals’ location histories as granularly as cell phones do, she nonetheless called Alaniz’s search unconstitutional and said that ALPR data collection is“persistent, dragnet-style surveillance.”

‘A major decision’

Many other ALPR cases are currently pending in courts. Should other judges rely on Chatrie as Hill did, it could change how law enforcement uses Flock and other ALPR systems. If officers need a warrant to search Flock vehicle location histories over an extended period of time, the technology will be significantly less valuable to police, experts said.

"Chatrie is a major decision that weighs heavily on ALPRs because the whole point of Chatrie is that the court is saying 'we're going to give you guideposts to distinguish between traditional policing, which you don't need a warrant for, and modern tools,’” Robert Frommer, the director of the Institute for Justice’s Project on the Fourth Amendment, said in an interview. 

“When you apply all those same factors that the [justices] laid out in Chatrie to ALPRs, it fits to a T,” he added. “We expect last week’s decision in Oklahoma to be the first of many to come.”

The Institute for Justice is suing the city of Norfolk, Virginia, for Fourth Amendment violations due to Flock searches. The judge in the Norfolk case ruled that because ALPRs only record fixed locations on public roads and do not track drivers on a constant basis, they do not meet the “whole of movements” standard. The case is under appeal.

A spokesperson for Flock said in a statement that Hill’s ruling “goes against the overwhelming weight of authority in similar cases across the country, including multiple recent decisions in Oklahoma, and we expect it will be appealed and ultimately overturned.”

“This ruling is limited to the specific facts of this case. It does not set controlling precedent and does not affect law enforcement agencies’ continued use of these important public safety technologies.”

Retrospective tracking

Prior to the Chatrie decision, the high court hadn’t heard a case involving modern-era police technologies and the Fourth Amendment since 2018, when the justices ruled in Carpenter v. United States that police using cell site location data to pinpoint a specific suspect’s whereabouts must obtain a warrant.

Hill is correct that ALPRs can capture enough historical location information to require a warrant for database searches, according to Sidney Thaxter, who serves as a senior litigator for the Fourth Amendment Center at the National Association of Criminal Defense Lawyers.

"ALPR networks run against us all even if we have not committed a crime and allow police to retroactively track our whereabouts with the press of a few buttons,” Thaxter said via email.

"This case correctly recognized that Chatrie holds that our location history is constitutionally protected and a warrant is required to track our physical movements,” he added. “The similarities between cellphone location records and ALPR records 'practically leap off the page.'

Thaxter also noted that Hill’s decision echoes the Chatrie opinion specifically because she ruled that how much location data police seek to use is irrelevant as long as surveillance technology provides law enforcement with what the justices called “a virtual panopticon with which to scrutinize its citizens’ activities.”

ALPRs are fundamentally unconstitutional when used without a warrant, Tom Bowman, policy counsel for the Security and Surveillance Project at the Center for Democracy and Technology, said via email.

“We expect to see similar challenges raised throughout the country,” he said. “The core product companies like Flock sell is a searchable nationwide record of where everyone has driven, and that is exactly what this court said police cannot reach without a warrant.”

“The [ALPR] business model is built on exactly the kind of retrospective tracking the Supreme Court has said requires a warrant,” Bowman said.