On May 14th, San Francisco became the first city to ban its police and other agencies from using facial recognition technology, citing the potential for civil rights violations. Several more cities and states are expected to follow its example in the coming weeks.

Already in use by governments around the world, surveillance software like Amazon’s Rekognition draws from vast databases of private citizens’ faces in an effort to identify criminal suspects, find missing children, and prevent fraud. At this point in its development, however, it also has a high failure rate. Studies by researchers at MIT and Georgetown have even found that the technology is significantly less accurate at identifying people with darker skin, potentially reinforcing preexisting racial biases.

Aaron Peskin, a member of San Francisco’s Board of Supervisors, said while introducing the measure in January that he had “yet to be persuaded that there [was] any beneficial use of this technology that outweigh[ed] the potential for government actors to use it for coercive and oppressive ends.”

Facial recognition technology can be integrated into surveillance cameras, police body cameras, and other electronic devices, enabling real-time identification of individuals within large crowds. According to Georgetown University researchers, if you’re an adult in the United States, there’s more than a 50 percent chance you’re already in a law enforcement facial recognition database — and it’s not clear exactly how those images are being stored and used.

Given that the San Francisco police department says it doesn’t currently use facial recognition, the city’s ordinance can seem a little preemptive. It also doesn’t apply to places like airports and ports, which are already overseen by federal agencies. But its supporters say the ordinance ensures that citizens have a say in how they’re watched and policed. While you can choose to keep your location-tracking iPhone at home or stay off Facebook in order to protect your own privacy, you can’t really opt out of facial recognition surveillance.

The ban doesn’t affect the technology that unlocks your iPhone or cameras owned by businesses and individuals, of course. Instead, it specifies that private individuals can still share tips or footage from private facial recognition cameras with police, but agencies can’t actively solicit information known to come from a facial recognition system. Critics of the ordinance worry that it’s too broad, permanently banning a technology that could soon play a key role in fighting crime.

“We want to use the technology to find missing elderly adults,” says Daniel Castro, Vice President of the Technology and Innovation Foundation, in a recent interview with NPR. “We want to use it to fight sex trafficking. We want to use it to quickly identify a suspect in case of a terrorist attack. There are very reasonable uses of the technology, and so to ban it wholesale is a very extreme reaction to a technology that many people are just now beginning to understand.”

Cities like Oakland, California and Somerville, Massachusetts are considering facial recognition bans of their own now, and Massachusetts Senate Majority Leader Cynthia Creem has even introduced an ACLU-backed bill that would impose a moratorium on facial recognition software in the entire state until accuracy concerns were adequately addressed. Meanwhile, as other cities and towns across the country continue buy into the technology, the government’s “facial biometrics” market is expected to grow from $136.9 million in 2018 to $375 million by 2025.

Images courtesy of Amazon Rekognition