San Francisco has rejected a policy that would allow police to use lethal robots, after its initial passage of the proposal drew widespread criticism.

The city's Board of Supervisors had passed the police proposal on Nov 29 by an 8-3 vote. It would have authorized police to deploy ground-based robots with deadly force in extraordinary circumstances, such as when a mass shooter or terrorist is threatening the lives of officers or civilians.

The policy sparked a public outcry, as opponents worried that it could lead to more police violence. Demonstrators protested the policy on Monday in front of San Francisco City Hall, holding "No Killer Robots" signs.

In a second vote on Tuesday, the supervisors voted unanimously to ban the use of robots for deadly force and sent the issue back to a committee for additional review, leaving it open for future review.

San Francisco police have a fleet of ground-based robots for reconnaissance, bomb disposal and rescue operations. They are not equipped with lethal force, but "could potentially be equipped with explosive charges", the police department said.

San Francisco was the first city in the United States to take steps to adopt an ordinance authorizing police use of deadly robots.

The first law enforcement agency that has used such technology is believed to be the Dallas Police Department. It killed a gunman by blowing him up with a bomb attached to a robot in 2016. The suspect was accused of fatally shooting five police officers.

The lethal use of robots has since become a controversial topic.

Supporters said it is helpful to apprehend suspects in mass shootings without putting officers' lives in danger. Opponents are concerned over the militarization of the police and potential disproportionate harm to communities of color.

During a heated debate at the San Francisco board meeting last week, Supervisor Aaron Peskin and others who supported the policy said it was necessary to empower police with such technology after several mass shootings across the country.

Mayor London Breed supported the measure, saying " (if) there is technology that can help to end the violence and save lives, we need to allow police to use these tools to save lives".

Board President Shamann Walton was worried that it would sow distrust within communities and not necessarily save lives.

"Most law enforcement weapons are used against people of color," Walton said at the meeting.

'Potential for misuse'

Supervisor Dean Preston, who voted against the policy during the first vote, said there is "serious potential for misuse and abuse of this military-grade technology, and zero showing of necessity".

"The people of San Francisco have spoken loud and clear: There is no place for killer police robots in our city," he said in a statement after the vote. "We should be working on ways to decrease the use of force by local law enforcement, not giving them new tools to kill people."

The San Francisco Public Defender's Office, in a letter, said the policy was "dehumanizing and militaristic".

The vote was the result of a new state law that requires police departments to have an inventory of equipment including certain guns and to seek explicit approval for their use, The Associated Press reported. The new policy needs another vote to take effect.

Agencies contributed to this story.

liazhu@chinadailyusa.com