These are screening portals rather than surveillance cameras. People walk through and sensors combined with machine learning attempt to distinguish weapons from ordinary metal objects, with an alert raised to staff or officers running the screening point. The proposition is throughput: screening large numbers of people faster than a metal detector and manual bag search would allow.

The distinction from ShotSpotter, also on this site, is that gunshot detection is acoustic and reactive, identifying that a firearm has already been discharged. Weapons screening is preventive and operates at an entry point.

The New York Police Department ran a month-long pilot across 20 subway stations, beginning at Fulton Street on 26 July, reporting 2,749 scans. The pilot found zero firearms, produced false positives and detected some knives. The department did not disclose how many passengers opted out or how many officers were required to operate the devices, and no agreement with Evolv had been finalised while outcomes were being assessed. Commuters and civil rights groups argued that mass subway scanning is impractical and unconstitutional. LA Metro has run a comparable pilot at Union Station.

Evolv has faced federal investigations into its marketing by both the Federal Trade Commission and the Securities and Exchange Commission, which is relevant context for any efficacy claim made about the technology.