Three decades ago, two United States Supreme Court cases determined that police can use deadly force if a "reasonable" officer in similar circumstances would have acted the same way.
So what happens when the public disagrees with the police about what might be considered reasonable?
California lawmakers introduced a bill Tuesday that would tighten the state standard for use of lethal force to "necessary" – when there are no alternatives for the officer to consider in that situation. Police would not be justified in killing the suspect if their own actions caused the deadly force to become necessary.
Assemblywoman Shirley Weber, a San Diego Democrat who is carrying the bill, said the current standard is too broad because it legitimizes the fear that sometimes causes officers to act abruptly without first trying to deescalate a confrontation. Police should only use lethal force, she said, when there is an immediate threat to their life or someone else nearby.
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"We want to put it in their mind that there are other options that they should utilize prior to that, that using deadly force is an extreme option," Weber said. "That's force you can't bring back."
The measure follows the recent shooting of Stephon Clark in south Sacramento, which has galvanized a national debate over policing practices.
Clark, 22, was shot last month after being chased into his grandmother's backyard by two officers responding to reports of a man breaking car windows. Police said the officers thought Clark had a gun; after the shooting, they determined he was holding a cellphone.
"That's not a reason to kill a person, because they're breaking in windows," Weber said. "People are tired, and I hope it is a point where everybody comes together. Even law enforcement should be tired of having to justify things and want to look at a new way of doing them."
Fierce opposition from law enforcement organizations has largely blocked prior legislative efforts to address police shootings, and this bill will likely face an uphill battle as well. Police across the country have raised concerns that limiting their options for using force would make their jobs more dangerous.
But the outcry over Clark has pushed lawmakers to revisit the issue. Sen. Nancy Skinner, D-Berkeley, this week announced another bill to open up law enforcement records related to serious use of force by an officer, which are severely restricted in California.
"The law needs to follow where the community norms are going," said San Francisco District Attorney George Gascón, who is supporting Weber's bill.
The American Civil Liberties Union of California is also behind the measure. Legislative advocate Lizzie Buchen noted that police in California use deadly force at a higher rate than other states; five local departments — Bakersfield, Stockton, Long Beach, Santa Ana and San Bernardino — are among the top fifteen in the country for killings per capita.
Currently, law enforcement officers can legally use deadly force as long as they perceive they are in danger. But advocates of the bill want them to first consider whether there are possible alternatives, such as taking cover and calling backup or issuing a verbal warning for a suspect to drop their gun.
"Accountability is a really important part of changing the culture," Buchen said. "What steps could you have taken instead of what you did?
"It doesn't mean they've tried all the other things, because we recognize that there are some situations where they're not going to be able to," she added.
William Terrill, a professor in the School of Criminology & Criminal Justice at Arizona State University whose research focuses on police behavior, said juries have generally given great leeway to cops on whether they faced a threat that justified lethal force. So without specifying what constitutes a "necessary" use of force, he said, Weber's bill might not change much in California.
But its provision to consider how the actions of an officer contributed to the lethal force could have a tremendous impact, Terrill said. In confrontations between police and suspects, the behavior of each builds on the other, he said, yet an officer only has to articulate what the suspect did to make them feel threatened to legally justify their use of deadly force.
"If California moved forward with this, they would be at the forefront," Terrill said.
Assemblyman Kevin McCarty, D-Sacramento, said he hoped the bill would "save lives and bring about justice" by spurring local agencies to review their own policies on use of force and change their training to emphasize deescalation.
He acknowledged that it is hard to be a "Monday morning quarterback" on situations like the Clark shooting, but the availability of body camera footage allows the public to decide for themselves whether they are comfortable with how an officer acted.
"Reasonable is in the eyes of the beholder," he said.