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by Peter Moskos

December 12, 2015


Anybody know if ShotSpotter is good? From an NYPD press release:
This is one of more than 30 firearms that have been recovered since the inception of the ShotSpotter program, back in March of this year.
Three guns a month doesn't seem like so many. But then to get 30 guns off the streets, back in the old stop-and-frisk would have meant stopping 26,370 people!

How does ShotSpotter work in practice? Is a response mandatory or discretionary? What about false positives?


Boomhauer said...

In D.C., someone in the Command Information Center calls out ShotSpotter and the dispatcher sends someone. A response is required unless there's sufficient reason (i.e. witnessed fireworks or construction going on where the shots were detected). A report for "Sounds of Gunshots" is also required.

There were a lot of false positives in the beginning, however the system has slowly been improving. But frequently units get sent on wild goose chases with no casings or other evidence found. Sensors in high crime areas often go down and aren't replaced for months which negates the intent of Shotpotter.

On the investigations side, it's useful for sussing out if there was likely one shooter or multiple shooters, if it was a mutual gun battle, and where shots started and ended. I can't, however, recall the last time in my district it was make or brake on a felony case.

Moskos said...


An actual written report required for each call?! Or just an oral code? (Or whatever it's called in DC)

Unknown said...

The way I've seen it work in brooklyn so far has led to a lot more reckless endangerment reports with a bunch of recovered shell casings. We haven't had all that many false positives given the noise in the neighborhood. The operations center at 1pp comes over the division radio and then a unit must respond and do a canvass. Here the sgt has to do a report at the end of each tour In regards to each shot spotter. I haven't seen it doing much in regards to recovering any firearms however.

Adrian said...

In Rochester, it's very useful for investigations, for the reasons Boomhauer said. How many shots were fired vs how many casings/strikes do you find? Also getting the exact time of the shots fired, and whether there were multiple guns, etc. Also it's useful to corroborate intel. Bob says in his interview that he was carrying a gun because he was shot at two weeks ago at Hudson/Alphonse by Bill. You check shotspotter and it shows 3 shots fired at Hudson/Alphonse two weeks ago. That helps confirm Bob's credibility and a lot of those get zero 911 calls, so otherwise it'd be lost.

In terms of patrol response, it's as good as what you put into it. The system learns what a gunshot sounds like versus what a firecracker sounds like. But if, in the beginning, you don't bother entering in the outcome of each activation, then the system doesn't learn and you get lots of false positives.

Boomhauer said...

An actual written report required for each call?! Or just an oral code? (Or whatever it's called in DC)

Unless an officer can definitely say that it was fireworks, construction noise, etc. then a written report is required. It's usually a few sentences. Depending on the district a daywork official may send people out to look for casings during daylight hours.

Like Michael Santoro said, there hasn't been much done with regards to actually recovering firearms for ShotSpotter. Most guys are smart enough to shoot and then roll out before MPD gets there.