Cambridge votes to end ShotSpotter contract

The city of Cambridge voted Monday to end its contract with ShotSpotter, a gunshot detection system used by police to identify possible shootings in real time.

The technology deploys a network of acoustic sensors mounted above streets to detect gunfire-like sounds and automatically alert law enforcement when a suspected shot is heard.

The City Council’s decision follows criticism from opponents who argue the system is unreliable and can contribute to over-policing. They have also raised concerns about potential links to federal immigration enforcement.

Cambridge’s move comes after Chicago announced in February 2024 that it would not renew its own contract for the technology.

Five councilors voted to terminate the contract, while two opposed the measure and two voted present during this week’s council meeting, according to Boston.com.

Under the decision, the city manager and police department must discontinue use of ShotSpotter within 90 days, and the devices will be removed from locations around Cambridge.

The system is operated by SoundThinking, which says the technology is designed to save lives, expedite police response and help investigators recover more evidence, with alerts relayed to law enforcement within 60 seconds.

During Monday’s meeting, City Manager Yi-An Huang and acting Police Commissioner Pauline Wells supported keeping ShotSpotter in place. Police cited 11 incidents when the system detected gunfire but did not receive 911 calls.

Critics say the technology lacks sufficient independent scientific validation, pointing to reported false positives and arguing it can be triggered by other loud noises such as car backfires.

They also noted that SoundThinking operates a law enforcement database that is allegedly related to Immigration and Customs Enforcement, an agenda considered deeply unpopular in Cambridge.

Councilor Ayah Al-Zubi, a co-sponsor of the resolution calling to decommission ShotSpotter, said the arrangement raises broader concerns about data sharing.

"It does pose a privacy and safety risk for residents, especially when the federal government has a relationship with the company and it’s not reliable," Al-Zubi said. "There was once a time, over a decade ago, where there was an interest in this technology, but now we know more about its effectiveness and its consequences."

The company responded to the accusations in a statement to the Boston Globe, defending the effectiveness of its technology.

"SoundThinking is proud to have successfully served the Cambridge Police Department and the citizens of Cambridge with gunshot detection services since 2014," the company said.