In the Chicago lawsuit filed by Michael Williams, a Chicago resident who served 9 months in jail before charges against him were dismissed, gunshot detection manufacturer Shotspotter released a 19-page operational document to the plaintiffs. The document was the only response made available for a discovery request for all guidelines, manuals and scientific materials.
The document, which you can read in its entirety below, sets out criteria for the company’s technicians to overrule machine judgments about what is, and is not, gunfire. According to the company’s sworn testimony in 2021, such reversals occur approximately 10% of time.
Among the factors to be considered are: a sideways Xmas tree shape to the sound waves, 100% certainty in the mind of the human reviewer that gunshots did or did not occur, proximate incidents, and the location and time when the incident occurred. Human reviewers are given a brief interval of a minute to overrule the machine’s judgment.
In Williams’ case, the then 65 year old Black grandfather was accused of shooting Safarian Herring inside a car on Chicago’s South Shore with the primary evidence being a Shotspotter report that had been modified by a human technician to relocate the location of the sound from where the sensor had picked it up.
In a similar case a few years earlier and across the country, Silvon Simmons, a Black air-conditioning repairman in his 30’s, was charged with four felonies and jailed for a year and a half after being shot four times by police. In Rochester, the Shotspotter report was adjusted several times after the fact including being reclassified from helicopter noise, to three shots, and then four shots and then five shots to account for police claims that Simmons had fired one shot at them prior to the four shots fired by the police. Simmons was acquitted of all 4 felonies, and is now suing the City of Rochester and Shotspotter for false imprisonment.
The operations document provided below was released to the Associated Press after being unsealed in the Williams case. Shotspotter lost an attempt to keep the document sealed as a proprietary trade secret.
The document’s inclusion of factors like “certainty of mind” indicate that subjective accounts from law enforcement customers may result in some reversals. The inclusion of factors like “proximal incidents” and the “time and location of the incident” also point to predictive indicators and profiling being used to overrule the algorithm. Considering the “location” suggests that incidents in perceived to be “bad neighborhoods” are probably more likely to be tagged for human reversal.
Online news site Vice was sued by Shotspotter for defamation after they wrote an article alleging that the company changed gunshot reports at the request of their police department customers. The defamation claim was dismissed. The release of this document supports the allegations made by Williams and Simmons in their lawsuits and in the Vice article.