San Francisco, often a testing ground for new technologies, has banned local government agencies – including the police – from using facial recognition technology.
The San Francisco Police Department doesn't currently use facial recognition, but did carry out a trial between 2013 and 2017 to test its usefulness.
The rule is part of a new anti-surveillance ordinance, which the city's board of supervisors approved on 14 May, and which will come into effect in June.
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The ban doesn't include businesses or private residents from using security cameras with facial recognition, so homeowners won't need to throw out their Nest cameras, and police officers can use footage from privately owned cameras to help with investigations. San Francisco Airport and the Port of San Francisco are also exempt.
"We all support good policing but none of us want to live in a police state," San Francisco supervisor Aaron Peskin told CNN Business in a statement.
The board of supervisors decided to support the ban because of facial recognition's potential for discrimination against people of a particular race or ethnicity, presenting too many false positives.
"The propensity for facial recognition technology to endanger civil rights and civil liberties substantially outweighs its purported benefits," says the ordinance, "and the technology will exacerbate racial injustice and threaten our ability to live free of continuous government monitoring."
It's expected that other US cities, and some states might follow San Francisco's example to protect their citizens' rights.