Gunfire pinpointed, then privacy debated

ShotSpotter, produced by a company that bills itself as the “world leader in gunshot detection,” added to its media credits this week with an article in The New York Times. But while many police departments are singing the praises of the acoustic monitoring technology, it continues to raise concerns about how far law enforcement can go to do its job.

The system, developed by SST Inc. of Mountain View, Calif., pinpoints the location of gunshots by triangulating the sound via sensors mounted on utility poles, buildings and other structures. It produces alerts that detail the number and exact time of the rounds fired, the position of the shooter (or shooters), and their speed and direction of travel if they are moving.

Cities can buy the equipment from SST and monitor the alerts themselves, or they can contract with the company to do it for them. Technicians at SST assess each alert to determine its accuracy, then send it to the appropriate PSAP “within seconds,” the company says. SST claims a 99 percent accuracy rate in differentiating gunfire from other loud noises like fireworks or cars backfiring.

Proponents say ShotSpotter speeds the response of police officers to the scene of a shooting, bolstering arrest rates, deterring additional crimes and saving the lives of victims who otherwise might have died. “Now when we pull up on a scene, we have 100 percent knowledge if there was actually a shot,” says a Springfield, Mass., police sergeant quoted on the company's website. “It makes your approach different.”

One problem, critics say, is that the system also can record other sounds of the city—doors slamming, cars honking, people arguing—while it records the gunshots. The Times said a ShotSpotter recording of a street argument in New Bedford, Mass., in December is likely to play a role in the case of two men charged with murder.

A defense attorney in the case said the recording could constitute a privacy violation and that the technology is “opening up a whole can of worms. If police are utilizing these conversations, then the issue is where does it stop?”

The company says that voices do not trigger ShotSpotter sensors, “which are placed in elevated locations in order to enhance their capability as well as ensure citizen privacy.” James Beldock, a company VP, told the Times that the system was not intended to record anything except gunfire and that cases like New Bedford's were extremely rare.

The issue could end up playing out in the courts, but in the meantime, it's likely that law enforcement will continue to turn to ShotSpotter and other gunfire detection systems as police budgets are trimmed and hosted subscription services become more available. It's a monitoring trend worth watching.