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.
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.