The ShotSpotter system and the value of diverse juror perspectives

Erik Loomis points to this AP story on ShotSpotter, a system that police and prosecutors use to identify gunshots, react to potential crimes, and prosecute suspects. The AP story raises serious questions about the accuracy and integrity of the system. You can click through for their story, which is gripping and definitely worth a read.

The ShotSpotter story reminded me of an experience I had as a juror several years ago. The charges in the case were pretty straightforward. Four college kids were walking home from a bus terminal when they were approached from behind by three men. There was a loud bang that the victims interpreted as a gunshot. They turned around, their assailants said they were armed and robbed them. The cops quickly found the suspects, including the one who was on trial.

The evidence was fairly compelling, and we eventually convicted the defendant, but there were also problems with the evidence and we took three or four days to reach a verdict. One problem was that the most important charge was armed robbery, but no gun was found. The victims thought they had heard a gunshot and a ShotSpotter system had recorded a gunshot. But the incident had happened at a bus depot, and there was some chance the “gunshot” had been the sound of a bus backfiring. There was some testimony about the ShotSpotter system; I don’t remember the details, but it amounted to little more than “trust me”.

We were having a not-so-interesting and not-so-well-informed discussion of the chance that the noise the victims heard could have been a bus rather than a gun, when a young black guy on the jury spoke up. He said, more or less, the following: “My friends and I were standing in front of a bus at xxxx (another bus depot) and the bus backfired. We thought it was a gunshot, so we ran. There were some cops across the street. They thought it was a gunshot and that we had fired it, so they started chasing us.”

Now, if I remember correctly, he (the young black guy) still thought it was likely they had heard a gunshot. Still, it was a remarkable example of the value of diverse perspectives. It would have been easy for a jury of middle class white folks who don’t take the bus, don’t worry much about gunshots, and don’t get chased by cops to just assume that it’s easy to distinguish a bus backfiring from a gunshot, or to assume that buses don’t backfire that often, etc.