The Washington PostDemocracy Dies in Darkness

AI may be searching you for guns the next time you go out in public

A Massachusetts company says it could help stop shootings like the Tops massacre in Buffalo and the Robb Elementary attack in Uvalde, Tex. Its surveillance product is increasingly popular.

Fans entering a Columbus Crew soccer match pass through Evolv's AI readers. The system has become increasingly popular as gun violence in the United States has risen, even as critics issue warnings. (Evolv Technology)
8 min

When Peter George saw news of the racially motivated mass-shooting at the Tops supermarket in Buffalo May 14, he had a thought he’s often had after such tragedies.

“Could our system have stopped it?” he said. “I don’t know. But I think we could democratize security so that someone planning on hurting people can’t easily go into an unsuspecting place.”

George is chief executive of Evolv Technology, an AI-based system meant to flag weapons, “democratizing security” so that weapons can be kept out of public places without elaborate checkpoints.

As U.S. gun violence like the kind seen in Buffalo and now Uvalde, Tex., increases — firearms sales reached record heights in 2020 and 2021 while the Gun Violence Archive reports at least 198 mass shootings since January — Evolv has become increasingly popular, used at schools, stadiums, stores and other gathering spots.

Its growing use at schools was thrown into relief Tuesday with the Robb Elementary School shooting, which claimed the lives of at least 21 people, including 19 children.

To its supporters, the system is a more effective and less obtrusive alternative to the age-old metal detector, making events both safer and more pleasant to attend. To its critics, however, Evolv’s effectiveness has hardly been proved. And it opens up a Pandora’s box of ethical issues in which convenience is paid for with RoboCop surveillance.

“The idea of a kinder, gentler metal detector is a nice solution in theory to these terrible shootings,” said Jay Stanley, senior policy analyst for the American Civil Liberties Union’s project on speech, privacy, and technology. “But do we really want to create more ways for security to invade our privacy? Do we want to turn every shopping mall or Little League game into an airport?”

Evolv machines use “active sensing” — a light-emission technique that also underpins radar and lidar — to create images. Then it applies AI to examine them. Data scientists at the Waltham, Mass., company have created “signatures” (basically, visual blueprints) and trained the AI to compare them to the scanner images.

Executives say the result is a smart system that can “spot” a weapon without anyone needing to stop and empty their pockets in a beeping machine. When the system identifies a suspicious item from a group of people flowing through, it draws an orange box around it on a live video feed of the person entering. It’s only then that a security guard, watching on a nearby tablet, will approach for more screening.

Dan Donovan, a veteran security consultant who rents Evolv’s systems out to clients for events, says that by allowing guards to focus on fewer threats, it avoids the fatigue metal-detector operators can feel. Like other consultants, he notes no system probably would have stopped the Buffalo shooter, who began firing in the parking lot.

Consumers can expect to see Evolv a lot more. Sports franchises like the Tennessee Titans and Carolina Panthers now use it; so do the New York Mets and Columbus Crew. The Super Bowl at SoFi Stadium in February deployed it on an outside perimeter. In New York City, public arts institutions such as Lincoln Center are trying it. So is a municipal hospital. (NYC Mayor Eric Adams has touted it as a potential subway security measure, but small spaces and underground signal interference make that less plausible. Airports, with tighter standards, are also unlikely.)

North Carolina’s Charlotte-Mecklenburg school system, with 150,000 students, has also licensed Evolv. Theme parks are excited, too — all 27 Six Flags parks across the country now use it. Evolv has now conducted 250 million scans, it says, up from 100 million in September.

George believes accuracy and lack of friction make Evolv compelling. “No one wants a prison or an airport everywhere they go, which is what you have with a dumb analogue metal detector,” he said. “And the cost of doing nothing is going up by the day.”

The company, which went public last year, has raised at least $400 million, with Jeb Bush, Bill Gates, Peyton Manning and Andre Agassi among the investors. (The space is growing, with a system from Italian rival CEIA also gaining popularity.) Relying primarily on the four-year subscriptions it sells, Evolv more than doubled its revenue in the first quarter to $8.7 million compared to 2021, though also more than doubled its losses, to $18.2 million.

Retail stores are an appealing use case, George said, because people want to feel safe shopping but don’t want to be stopped and checked every time they walk in to buy some groceries. (About 60 people can be scanned every minute, Evolv says.) George said that when the system was installed at an Atlanta-area mall, Lenox Square, in January, it caught 57 guns in the first four hours.

Overall, George said, at least 15,000 guns were flagged by Evolv in the first quarter of 2022. (These numbers are not publicly vetted.)

But IPVM, a security-industry trade publication, concluded after a review that Evolv has “fundamental technological limitations in differentiating benign objects from actual weapons.” One issue, IPVM said, citing its examination of the company, is that some metallic objects confuse the AI, including particularly the ruggedly designed Google Chromebook.

IPVM says Evolv has not provided sufficient data. The publication also says the company will not engage with it due to its inquiries; it says the firm has even asked it to stop reporting on Evolv in the name of public safety.

In a statement to The Washington Post regarding the conflict, Evolv said: “We believe that publishing a blueprint of any security screening technology is irresponsible and makes the public less safe by providing unnecessary insights to those who may try to use the information to cause harm.”

Alan Cowen, a former Google scientist and AI expert, says he’d also worry about “adversarial examples,” in which bad actors learn how to circumvent the AI — say, by putting tape around a gun handle — as well as a delay in figuring this out because Evolv won’t flag it.

Some techno-ethicists say accuracy is only one fear.

“If it can reduce false positives while still catching the real positives, that seems like a benefit,” said Jamais Cascio, the author and founder of Open the Future, an organization examining technology’s consequences. “My concern is what happens when it moves beyond looking for weapons at a concert — when someone decides to add all kinds of inputs on the person being scanned, or if we enter a protest and a government agency can now use the system to track and log us. We know what a metal detector can and can’t tell us. We have no idea how this can be used.”

George says that no data is applied to a scanning subject and no information captured or catalogued. As for accuracy, he acknowledges the Chromebook has been an issue but says the algorithm is being improved. He suggests students might simply come to realize they need to hold them up on their way in to school, a small price to pay. “Why shouldn’t there be a system where kids can learn safely and also enter without breaking stride?” he asked.

Whether that will be possible in large districts like Charlotte-Mecklenburg, though, remains to be seen. Requests for comment from the police department overseeing the district’s security were not returned.

Several Evolv clients The Post spoke to say they’re happy with the system.

“We went from 30 metal-detector lines to four lanes, and we’re not stopping people for every cellphone or house key,” said Jason Freeman, Six Flags’ vice president of security, safety, health and environmental. He said overall stops have gone from 32 percent to 15 percent, with the great majority still not considered threats. The idea is not just to catch more weapons; it’s to waste less time on everything else.

Mark Heiser, venue director for the Denver Performing Arts Complex, says the system is light-years ahead of the metal detector. “We’d never go back,” he said.

Heiser cited fewer alarms for items like pen knives — “which is good, because it allows us to focus on [the more destructive weapons].” And, he noted, a lot of audience members feel freer walking in.

But Stanley of the ACLU remains unconvinced.

“Devices being more subtle is a good thing. But they can also be more insidious or even just annoying,” he said. “You’re going to have a lot of people shocked an umbrella tucked inside a coat pocket is suddenly leading to an encounter with a security guard.”