As the number of automated license plate readers (ALPRs) has skyrocketed nationwide, erroneous stops, detainments and arrests are becoming increasingly common.
This article was updated on July 10, 2026
In February of this year, a Flock camera in Sherwood, Arkansas, misread the license plate of an SUV, leading officers to detain an innocent couple at gunpoint while their six-week-old baby sat alone in a car seat in the back of the vehicle.
“Those cameras are placed everywhere, and they hit license plates,” one of the officers explained as they uncuffed the couple after realizing their error several minutes later. “I’m not gonna say they’re completely perfect, because, you know, that’s modern technology.”
As the number of automated license plate readers (ALPRs) has skyrocketed nationwide, errors like this one are becoming increasingly common. An Institute for Justice (IJ) review of media reports and court records finds there have been at least 26 such cases since 2018, with the majority of those happening since 2023.
What happens when innocent people are stopped
In recent months, stories have proliferated about innocent motorists enduring the indignity of being pulled over repeatedly until police departments figure out the root cause of the ALPR errors. But those drivers have it relatively easy: in nearly two-thirds of the cases IJ analyzed, officers did not realize their error until after they had drawn and pointed their guns at innocent people.
“Every one of those stops is a high-risk encounter where a wrong move, a misunderstanding, or a moment of fear can turn deadly,” said Michael Soyfer, an IJ attorney who is representing residents of San Jose and Norfolk in lawsuits challenging their cities’ ALPR surveillance networks. “No one should have to prove their innocence on the side of the road because a camera couldn’t tell a zero from an O.”
The recent uptick in ALPR errors owes largely to Flock Safety, which in the past several years has become the leading ALPR provider in the market. The company claims its cameras accurately capture 93 out of every 100 license plates that pass by them.
It all adds up to more than 20 billion individual license plate readings each month, according to Flock’s marketing materials. Even taking Flock’s claims at face value, a 93% accuracy rate implies well over one billion inaccurate readings per month, which is especially concerning given that the vast majority of plates scanned are not relevant to an investigation.
Those machine errors happen for a variety of reasons. Minor obstructions like dirt or license plate holders can sometimes throw off the devices’ character recognition, for instance. And the machines often have trouble distinguishing between visually similar characters, like 0 and O, or 2 and 7.
How human errors contribute
But those machine errors account for about one-third of the mistakes in the cases IJ identified. The rest involved human error, with officers entering wrong information into the system or misinterpreting what the ALPR data says.
Last year in San Diego, for instance, officers were searching for a red Alfa Romeo connected to an attempted carjacking. The officers didn’t have a plate and were instead relying on Flock’s “vehicle signature” technology, which captures detailed characteristics of individual cars like make, model, and color.
The Flock system gave them a positive hit on a superficially matching car—but it was a totally different red Alfa Romeo, located five miles away from the crime at the time it occurred. Officers nevertheless arrested all three of the car’s occupants. One passenger spent nearly a month behind bars during the holidays before officers realized their error and set him free.
In other cases, officers have entered multiple variations of the same license plate into the system, in part to account for ALPR character recognition errors.
“The Constitution requires real suspicion before the government can seize someone at gunpoint, and a computer hit that no one bothered to confirm doesn’t come close,” Soyfer said.
The list below includes only cases involving stationary ALPRs like Flock’s. Cases of mistaken identity involving vehicle-based ALPRs, traffic cameras, or toll cameras are not included. The review builds on previous efforts to tally ALPR errors, including those by CBS News and the Electronic Frontier Foundation.
These 26 cases are most likely an undercount, perhaps by a significant margin. There is no comprehensive database of ALPR errors, and IJ has identified just one jurisdiction that publishes regular reports of such errors: Oak Park, Illinois. Those show that, in a typical reporting period, one-third or more of the traffic stops prompted by a Flock alert resulted in the drivers being released due to data problems.
“There is no evidence whatsoever that Flock Safety ALPRs have played a meaningful role in any Oak Park crime investigation since their installation in 2022,” the oversight board publishing those reports concluded in 2025.
Oak Park ended its contract with Flock in August of that year.
List of known cases
machine error
Jun. 2026
Plymouth, MN
Plymouth police tracked an automobile writer for days and then detained him and his wife in a Kohl’s parking lot after Flock cameras failed to detect small characters on the plate of a Range Rover test vehicle.
Camera: Flock
human error
Apr. 2026
Cherry Hills, CO
A Colorado driver was repeatedly pulled over after officers mistakenly put his license plate number on a Flock hotlist.
Camera: Flock
Based on a Flock capture, officers mistook an innocent driver’s car for one that was at the scene of a deadly accident. The driver was jailed for 13 days.
A Flock camera misread a digit on an innocent couple’s vehicle, prompting officers to pull them over and order them out of the car at gunpoint.
Another Colorado driver was repeatedly pulled over after officers mistakenly put her license plate number on a Flock hotlist.
Based on a Flock capture, officers mistook an innocent driver’s car for one that was at the scene of an attempted carjacking. The driver was jailed for nearly one month.
An officer misinterpreted Flock captures to blame an innocent woman for a series of thefts.
Yet another Colorado driver was repeatedly pulled over after officers mistakenly put her license plate number on a Flock hotlist.
After data in the Flock system incorrectly linked a suspect’s vehicle to his innocent father, officers detained the wrong man.
Officers detained an innocent man at gunpoint after a Flock camera misread his license plate.
After a Flock camera misread an “O” as a “0”, officers detained two grandparents at gunpoint while their three-year-old granddaughter watched from the car.
Officers misidentified a vehicle based on an ALPR alert, detaining an innocent teenager at gunpoint.
After a Flock camera misread a “7” as a “2”, officers detained an innocent driver at gunpoint, sicced their dog on him, and jailed him for several hours.
machine error
Feb. 2024
York County, SC
An innocent motorist was detained at gunpoint after a Flock ALPR misread a character on his license plate, flagging the car as stolen. The sheriff’s office claimed the misread was due to a tinted license plate cover.
Camera: FLOCK
After a Flock camera failed to distinguish between temporary and permanent license plates, sheriff’s deputies detained an innocent couple at gunpoint.
Officers misinterpreted ALPR data and detained an innocent woman at gunpoint, put her autistic child in the back seat of a police car, and impounded her vehicle for several weeks.
Officers misinterpreted a Flock alert for a stolen car and detained two innocent men at gunpoint.
After a Flock camera misread a digit of their license plate, officers detained two innocent sisters at gunpoint.
After officers entered incorrect information into the ALPR system, they detained an innocent teenager at gunpoint.
Officers misinterpreted ALPR data and detained an innocent woman at gunpoint.
After officers failed to remove a license plate from a hotlist, they pulled over and detained an innocent driver.
An ALPR hit led to an innocent woman’s arrest after officers entered incorrect information into the license plate reader system.
After officers failed to remove a recovered rental vehicle from a hot list, they detained two innocent women.
After an ALPR misread a license plate that was partially obscured by dirt, officers detained the driver at gunpoint.
After an ALPR misread a minivan’s license plate, officers detained a woman and four children at gunpoint.
After officers failed to update a hotlist about a stolen rental vehicle that had been recovered, a Vigilant ALPR flagged the vehicle and the driver and his brother were detained at gunpoint.
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