San Francisco’s ruling Board of Supervisors has voted to let the city’s police use robots that can kill.
The measure permits police to deploy robots equipped with explosives in extreme circumstances.
Dr Catherine Connolly, from the group Stop Killer Robots, said the move was a “slippery slope” that could distance humans from killing.
The city’s police – the SFPD – told the BBC they do not currently operate any robots equipped with lethal force.
They said though that there may be future scenarios in which lethal force could be used by a robot.
A spokesperson for the police said “robots could potentially be equipped with explosive charges to breach fortified structures containing violent, armed, or dangerous subjects”.
They also said robots could be used to “incapacitate, or disorient violent, armed, or dangerous suspects who pose a risk of loss of life”.
Advocates for the measure said it would only be used in extreme situations.
Opponents, however, say the authority could lead to further militarisation of the police force.
The measure passed, with an amendment on Tuesday specifying that officers could only use robots wielding deadly force after employing alternative de-escalation tactics.
The board also stipulated that only a limited number of high-ranking officers could authorise its use.
This type of lethal robot is already in use in other parts of the United States.