Evolv Express weapons detection

Released: 2020

Evolv Express is an 'AI-based weapons screening system' that detects guns, knives, bombs and other concealed offensive weaponry at schools, hospitals, sports and entertainment venues, and public events.

Massachusetts-based Evolv Technology, which manufactures Evolv Express, says it uses 'proven' AI and machine learning to enable scanners to create unique 'signatures' of weapons that differentiate them from items such as computers or keys, thereby reducing manual checks and preventing long queues.


In January 2022, video research company IPVM discovered that Evolv Express mistakes certain Chromebooks as weapons 60 to 70% of the time.

In October 2022, 18 year-old student Ehni Ler Htoo was stabbed multiple times by a fellow student at Proctor High School in Utica, New York, armed with a nine-inch hunting knife, despite the school having installed Evolv Express

In November 2022, BBC News reported that an assessment by the US National Center for Spectator Sports Safety and Security (NCS4) had found that whilst Evolv Express detected many types of guns 100% of the time, it failed to detect large knives 42% of the time. The test also found the product fails to detect certain types of bombs and their components.


Civil rights advocates are also concerned that Evolv Express and similar systems could easily be combined with other surveillance technologies, such as facial recognition.


Marketing claims made by Evolv have repeatedly been questioned by independent security experts and others. 

The company markets Evolv Express as being 'effective at preventing shootings.' But it has offered little evidence supporting this claim, and has refused IPVM permission to test its product. And, as a number of commentators have pointed out, many school shootings are carried out by gunmen openly carrying their weapons.

Evolv Express is promoted as a 'line-free' system that requires 'no stopping,' emptying of pockets, or removing the contents of bags, and that fewer security staff are needed than with traditional metal detectors. 

However, an August 2022 VICE News report suggests that many organisations using Express are causing 'chaos' by failing to detect common handguns, mistaking everyday school items for deadly weapons, and failing to deliver on the company’s promise of frictionless school security. 

An Freedom of Information request made by IPVM and shared with BBC News shows Evolv had made multiple 'tracked changes' to the NCS4 test report, including deleting sections critical of Express, resulting in a partial 25-page public report. 

Evolv’s full, private report is only available upon request with the company 'under non-disclosure to qualified security professionals with direct responsibility for deployment of Evolv Express.'

NCS4 evaluators said they 'Recommend full-transparency to potential customers based on data collected.' 

Operator: Charlotte-Mecklenburg Schools; Six Flags; Spartanburg School District Six; Manchester Arena; Metropolitan Museum of Art; Lincoln Center; Dollywood; Kennywood; Utica Schools Board; Proctor High School
Developer: Evolv Technology

Country: UK; USA

Sector: Govt - education; Media/entertainment/sports/arts

Purpose: Detect weapons

Technology: Computer vision; Object recognition
Issue: Accuracy/reliability; Dual/multi-use; Surveillance

Transparency: Governance; Black box; Marketing


Research, advocacy

Investigations, assessments, audits

News, commentary, analysis

Page info
Type: System
Published: December 2022
Last updated: June 2023