Is Pasadena’s ShotSpotter System Actually Catching Criminals?
In February 2022, the City of Pasadena became the first municipality in Los Angeles County to adopt ShotSpotter, a controversial acoustic gunfire detection system. At the time, the promise was clear: real-time alerts would lead to faster police responses, reduced gun violence, and more criminals off the streets.
Fast forward to today—with the Pasadena City Council recently approving a new $661,500 three-year contract in early 2025—and a glaring question remains. For all the money spent and alerts generated, where are the prosecutions?
The High-Tech Promise vs. Hard Data
ShotSpotter (recently rebranded by its parent company as SoundThinking) utilizes a network of hidden microphones attached to lampposts and buildings, primarily deployed in Northwest Pasadena. When a loud bang occurs, the system’s algorithms and human reviewers determine if it is gunfire, dispatching police within seconds.
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The Pitch: Proponents, including Pasadena Police Chief Gene Harris, argue that the system bridges the gap of unreported shootings. Nationally, it is estimated that roughly 80% of gunfire goes without a corresponding 911 call.
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The Problem: While the technology certainly sends officers to the geographic coordinates of loud noises, the trail of evidence usually runs cold the moment they arrive.
The Glaring Lack of Prosecutions
A deep dive into the available data reveals a stark disconnect between the volume of technological alerts and tangible law enforcement outcomes, such as arrests and courtroom convictions.
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Low Local Hit Rates: In Pasadena, the system has logged hundreds of alerts since its inception (including 254 alerts between early 2022 and late 2023 alone). Yet, concrete data linking these alerts to actual prosecutions is shockingly thin. For perspective, during its first six months of operation in 2022, 63 alerts reportedly led to just two arrests.
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The False Positive Epidemic: National studies mirror Pasadena’s local friction. Research from the MacArthur Justice Center in Chicago found that nearly 89% of ShotSpotter deployments led to no gun-related crime. Microphones are easily fooled by fireworks, cars backfiring, and construction noise, leading to dead-end investigations.
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Courtroom Failures: Even when arrests are made in connection with an alert, ShotSpotter data is frequently challenged or withdrawn in court. Defense attorneys and independent researchers point out that the system’s acoustic algorithms have never been fully, independently peer-reviewed. Consequently, prosecutors are often hesitant to rely on it as primary evidence during trials, fearing it won’t hold up to judicial scrutiny.
The Cost to the Community
The lack of prosecutorial success makes the financial and social costs incredibly difficult to justify. Pasadena is spending hundreds of thousands of dollars—funded via asset forfeiture and city budgets—on a tool that critics argue functions more as an expensive placebo than a crime-fighting silver bullet.
Furthermore, these microphones are disproportionately placed in marginalized neighborhoods. Civil rights advocates argue that this leads to hyper-surveillance. When police are repeatedly dispatched to “high-alert” areas for what turn out to be false alarms, it increases the likelihood of unnecessary stops, searches, and heightened tensions with residents.
As Councilmember Rick Cole noted when voting against the 2025 renewal, the city needs “hard data” before doing business as usual, pointing to a frustrating lack of comparative response times and prosecutorial outcomes in official staff reports.
The Bottom Line
While no one denies the critical importance of getting medical aid to victims of gun violence as quickly as possible, evaluating a law enforcement tool requires looking at its ultimate efficacy in the justice system. If Pasadena’s ShotSpotter system is generating hundreds of alerts but failing to yield meaningful arrests and prosecutions, it is time to ask: are we paying for a solution, or just buying more noise?
