Images representing 117 million American adults – almost half the grownups in the country – can be found in the facial recognition databases maintained by US law enforcement agencies, according to a study conducted by the Center on Privacy and Technology at Georgetown Law School.

That figure is expected to grow as facial recognition technology becomes more capable and more commonplace. Yet such systems have very little oversight.
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“Transparency makes a lot of the problems we’ve noticed easier to detect,” said Frankle.

Some of these problems include: the disproportionate representation of African Americans in US law enforcement databases; the potentially chilling effect of facial recognition on free speech; lack of reliable information on the accuracy of facial recognition systems; and unsettled questions about the circumstances under which facial recognition might violate Fourth Amendment protections against unreasonable searches.
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At the same time, the utility of the technology remains open to question. Where public data about the efficacy of facial recognition searches exists, it’s not particularly compelling. “Of the FBI’s 36,420 searches of state license photo and mug shot databases, only 210 (0.6 per cent) yielded likely candidates for further investigations,” the study says. “Overall, 8,590 (4 per cent) of the FBI’s 214,920 searches yielded likely matches.”

What’s more, reliable metrics for the accuracy of facial recognition systems are scarce. For example, FaceFirst, facial recognition vendor, advertises “an identification rate above 95 per cent.” The CPT study claims this is misleading and cites a 2015 contract with the San Diego Association of Governments that disclaims any specific success rate: “FaceFirst makes no representations or warranties as to the accuracy and reliability of the product in the performance of its facial recognition capabilities.”
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The study cites a facial recognition test conducted with real-time video in Mainz, Germany, from 2006 to 2007, where accuracy was 60 per cent during the day and 10 to 20 per cent at night.
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“Face recognition can and should be used to respond to serious crimes and public emergencies,” the study concludes. “It should not be used to scan the face of any person, at any time, for any crime.”

Source: Meanwhile, in America: Half of adults’ faces are in police databases