A recent study on how Flock cameras influence crime rates has limitations that prevent firm conclusions from being drawn.
A recent working paper by scholars at the University of South Carolina examined the impact of Flock Safety’s automated license plate readers (ALPRs) on car theft and car theft clearance rates. The study—the first of its kind—purports to show a reduction in car thefts and an increase in the clearance rate after Flock deployment. Flock issued a statement latching on to these findings as a validation of the technology at a time of massive public backlash.
A closer look, however, reveals limitations in the study that suggest those claims are too strong. To add context and further inform public debate on the issue, the Institute for Justice (IJ) is releasing a new explainer on why the results should not be interpreted as showing that Flock ALPRs caused a decline in car thefts and increase in arrests.
Clearance rates for car theft were increasing and car thefts were decreasing before ALPR deployment
The working paper compares car theft and clearance rates in cities that deployed Flock ALPRs (the “treatment group”) with those that did not (the “control group”). It finds that ALPR deployment is associated with an 11% reduction in car theft and a 16% increase in car theft clearance rates.
The problem is that trends in the treatment group were already heading in the right direction for both thefts and clearance rates before Flock deployment, when compared to the control group. The study uses a design that can show causal effects, but only if trends are similar in both groups. In this case, the trends differed significantly. That makes it hard to tell if changes after deployment resulted from Flock or something else.
“Because there were already differences in arrests and theft trends before ALPR deployment, we don’t know if the differences after ALPR deployment were caused by ALPR deployment,” said IJ Senior Research Analyst Matthew West. The study’s authors acknowledge that the clearance rate result may be due to a “broader anti-theft initiative that included camera purchase”, among other possibilities. They note that the rise in clearance rates before ALPR deployment “prevents precise attribution to the cameras.”
The headline result on car theft depends heavily on how the data are weighted
The study only achieves its topline finding of an 11% reduction in car theft by weighting the results to favor agencies that had higher amounts of car theft before they installed ALPRs. If the data are instead averaged across all agencies (or weighted by population), the study finds no statistically significant change. This suggests, as the authors put it, that “the decline is concentrated in the jurisdictions” with more car thefts “rather than representing a uniform effect across adopting agencies”.
Further muddying the picture, any effects are not even uniform among agencies that had high levels of car theft before Flock deployment—as most agencies that adopted Flock ALPRs did. On average, this group actually saw a statistically significant increase in thefts after Flock deployment.
The upshot is that the topline 11% figure, even if causal, does not describe what happened in many if not most agencies that deployed Flock ALPRs.
Social factors further complicate the analysis
The study period included both the COVID-19 pandemic and the viral trend of Kia and Hyundai thefts. Both phenomena affected crime at different times, in different places, and in different ways, so it is difficult to isolate the effects of any given factor on car theft at a local level. If agencies adopted Flock when car theft was peaking locally, then a decline in cart theft could in part reflect things returning to normal instead of a drop in car theft from the installation of Flock ALPRs.
“Flock and its supporters are trying to exploit fear of crime to convince people to give up their rights,” said IJ Attorney Michael Soyfer. “Notably absent from the conversation is the cost to civil liberties through mass surveillance, wrongful detentions, and widespread abuse. Only by reaffirming our commitment to Fourth Amendment principles like a warrant requirement can we ensure that we are not giving up more than we are getting in return.”
The lack of those protections means ALPR technology can be easily abused, as IJ has documented hundreds of times. Our Plate Privacy Project is challenging the government’s arbitrary power to use ALPRs to surveil the entire driving public in court, with federal lawsuits filed against Norfolk and San Jose. We’ve drafted model legislation for policymakers aiming to reign in ALPR abuse and are tracking the hundreds of communities that have canceled their ALPR contracts in recent months.
To dig deeper into the limitations of the data on ALPR deployment and crime, read the full explainer prepared by IJ’s Strategic Research team.
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Facts Only
* A working paper from the University of South Carolina examined the impact of Flock Safety's ALPRs on car theft and clearance rates.
* The study found an 11% reduction in car theft and a 16% increase in car theft clearance rates in cities that deployed ALPRs compared to control groups.
* Trends in car theft and clearance rates were already changing before ALPR deployment in the treatment group relative to the control group.
* The finding of an 11% reduction in car theft relied on weighting results to favor agencies with higher pre-deployment theft amounts.
* Averaging results across all agencies showed no statistically significant change in car theft.
* Effects were not uniform among agencies that adopted Flock ALPRs; some saw a statistical increase in thefts after deployment.
* The study period included the COVID-19 pandemic and viral Kia/Hyundai thefts, which affected crime at different times and places.
* Advocates contend that ALPR technology can be used for mass surveillance without warrant requirements.
Executive Summary
A study examining the impact of Flock Safety's Automated License Plate Readers (ALPRs) on car theft and clearance rates presents mixed findings, highlighting significant limitations in attributing causality to the technology itself. The research compared cities that deployed ALPRs (treatment group) with those that did not (control group). The study found an 11% reduction in car theft and a 16% increase in car theft clearance rates in the treatment group. However, these trends were already moving in the right direction before the ALPR deployment when compared to control cities, complicating the determination of whether the technology caused the changes.
The findings are further complicated by data weighting; achieving the primary finding required weighting results toward agencies with higher pre-deployment theft rates. When averaging across all agencies, no statistically significant change was found. Furthermore, effects were not uniform across agencies that adopted the technology, with some observing an increase in thefts after deployment. Social factors, including concurrent events like the COVID-19 pandemic and viral vehicle thefts, introduced confounding variables, making it difficult to isolate the effect of ALPRs alone.
The analysis also shifts to civil liberties concerns, noting that advocates argue the technology is used to exploit fear of crime, raising serious questions about mass surveillance, wrongful detention, and Fourth Amendment rights without warrant requirements. Legal challenges are ongoing regarding the scope of government tracking enabled by ALPRs.
Full Take
The structure of this research demonstrates how statistical methodology can obscure critical real-world dynamics, particularly when dealing with complex social phenomena like public safety. The core limitation lies in the inability to establish a clear causal link because pre-existing trends were divergent between groups, leading to uncertainty about whether the observed post-deployment changes were attributable to the cameras or external factors. This mirrors broader problems where correlation is mistaken for causation; the narrative presented by Flock supporters relies on isolating a variable while ignoring the system's inherent complexity and confounding variables.
The reliance on specific weighting techniques to arrive at a "topline finding" reveals an underlying tension between statistical purity and practical relevance. When results are selectively weighted, the reported effect shifts from a generalized measure of technology impact to a measure tailored for specific institutional interests, failing to represent a uniform experience across the deploying agencies. Furthermore, framing the issue solely around crime statistics ignores the fundamental concerns raised by civil liberties advocates regarding pervasive surveillance.
This scenario reveals a pattern where technological deployment is often validated not by objective causal proof, but by aligning with pre-existing narratives of concern (fear of crime), which then justifies expansion of power. The failure to properly account for dynamic social environments and legal constraints means that the conclusion about crime reduction remains provisional and highly susceptible to narrative framing rather than pure empirical deduction.
Bridge Questions: If research methodology is insufficient to isolate effects in this context, what alternative, non-statistical frameworks exist for evaluating public safety interventions? How can policy be constructed when empirical evidence is inherently ambiguous regarding causality? What mechanisms must be established to ensure that the pursuit of security does not inadvertently erode constitutional protections?
Sentinel — Human
The article is a structured analysis that critically evaluates a study on surveillance technology by emphasizing methodological limitations and framing the issue within broader civil liberties debates, characteristic of investigative journalism.