Understanding Gunshot Detection Technology

High-tech police tool coming to more U.S. cities

Regardless of accuracy rates, the high-tech nature of ShotSpotter may dazzle juries. "It's the gee-whiz effect: It seems so scientific, it must be true, right?" says Jack King, a spokesman for the National Association of Criminal Defense Lawyers. If he was defending a client, he would move to keep gunshot acoustic evidence out. "If a district attorney wanted it in, I would make him put on some $1,000-an-hour experts to convince the court that it's scientifically reliable."

Data security will be one of the first questions. The entire system uses encryption, from sensor to server to dispatcher, says James Beldock, president of ShotSpotter. The server stores a record of each gunshot report that includes the time, the sensor readings, and calibration data.

"You can take data out of the system, and with graph paper and a little physics, you can come to the same answer," says Mr. Beldock. "It's going to go to court eventually, and I'm looking forward to it."

In the future, Boston and Minneapolis hope to pair ShotSpotter with surveillance cameras already in place in both cities. In a demonstration Saturday in Boston, a camera was able to automatically swivel and focus on the location of a fired gun within seconds.

"A technology that is installed for one purpose which is legitimate, could, down the road, be used for other purposes," says Carol Rose, head of the Massachusetts ACLU chapter. She says that gunshot detection systems are not inherently problematic - and may be useful - if used as advertised. "[But] the city council needs to take steps to make sure that listening devices used to triangulate gunshots aren't used to listen to private conversations."

The company says the sensors don't pick up voices.

The system would cover 5.6 square miles of Boston, in places where gun violence is highest, say city officials.

"[Over four years,] $375,000 a year is nothing to ensure public safety," says Ron Consalvo, a Boston city councilor who pushed for the system. "It does take more police on the street, and we're doing that.... But it also takes the police department doing everything they can to seize the latest technology to do their job better."

(c) Copyright 2007. The Christian Science Monitor