Outrage at Derek Chauvin was apparent from the moment video surfaced of his knee pressed into George Floyd's neck for 9 ½ minutes.
Chauvin, the former Minneapolis police officer who was convicted of murder in April, became the face of intolerance, injustice and police brutality, his actions driving worldwide protests against those ills.
But the inaction of the three colleagues who stood by as he killed Floyd has similarly spurred change.
The lack of response that day by the former officers, Tou Thao, J. Alexander Kueng and Thomas Lane — whose federal trial begins this week on charges that they violated Floyd's civil rights — has led multiple states to codify through legislation or policy that officers have a duty to step in if they witness a colleague using excessive or unauthorized force.
As of October, at least 18 states required officers to intervene or required law enforcement agencies to adopt policies imposing such a duty on officers, and at least 17 states required officers to report when another officer uses excessive force, said Josh Parker, a senior attorney at the Policing Project at New York University School of Law.
Illinois, Maryland, Massachusetts and Washington are among the states that have enacted comprehensive use-of-force statutes after Floyd's murder, Parker said.
The Massachusetts legislation, An Act Relative to Justice, Equity and Accountability in Law Enforcement in the Commonwealth, allows for the decertification of officers who don't intervene "to prevent the use of excessive or prohibited force by another officer."
A similar measure in Maryland makes it a misdemeanor offense for an officer to "knowingly and willfully" fail to attempt to stop or prevent a colleague from using excessive force, punishable by a maximum penalty of five years in jail and/or a fine of $10,000.
Manka Dhingra, the primary sponsor of Senate Bill 5066, which the Washington Senate passed in February, said the legislation was inspired by the deaths of people of color at the hands of police, including Floyd, 46, a Black man, who was restrained on the ground in the prone position until he died.
Kueng knelt on Floyd's back and Lane held down his legs, according to evidence presented at Chauvin's state trial. Thao stood nearby and kept bystanders at bay; some of them shouted at Chauvin to get off Floyd's neck.
In the federal case, Thao and Kueng are accused of failing to stop Chauvin from kneeling on Floyd and of failing to help him. Lane, who was recorded on body camera video twice asking whether Floyd should be turned on his side, is charged only on the latter count. The men also will be tried later on state charges of aiding and abetting second-degree murder. Chauvin was convicted in April of state murder and manslaughter charges, and last month, he pleaded guilty to a federal count of violating Floyd's civil rights.
Dhingra said the bystander video of Floyd's final moments was "horrid," as was "the officers' standing around and not intervening" when their department had a duty-to-intervene policy at the time.
"I think a lot of law enforcement agencies will tell you that that is part of the policy," said Dhingra, a former prosecutor. "The bottom line is this is not happening. And so a lot of this is about changing cultures."
Supporters say the measures give states new ways to root out rogue officers and hold police officers accountable to the citizenry, instead of one another.
Parker said the deaths of Floyd and Eric Garner in New York — both of whose dying pleas included "I can't breathe" — could have been avoided if other officers had intervened.
"States and law enforcement agencies should be using every tool in their toolbox to ensure this tragic history doesn't repeat itself. Imposing a duty to intervene on officers is one such tool," he said.
While Dhingra and other policing experts said it is hard to measure the success of such policies just yet, Washington state "has had a decline in officer-involved shootings in the last year," Dhingra said, which she said she believes can be attributed, in part, to this measure.
Alexander Shalom, the senior supervising attorney for the American Civil Liberties Union in New Jersey, said: "We shouldn't shy away from solutions that are not complete but that are still helpful. And this, I think, qualifies as exactly that."
Not everyone sees the value in the laws.
Retired Officer De Lacy Davis said he believes establishing a legal duty to intervene "is nothing more than a political reaction to failed accountability in the policing system" that won’t be adequate to knock down the so-called blue wall of silence that keeps officers from reporting colleagues' wrongdoing, criminal or otherwise.
Davis said he reported colleagues for excessive force multiple times during his 20-year career with the East Orange, New Jersey, Police Department. In a 1996 case, he said, he witnessed a colleague assault a civilian in a municipal building. The colleague wasn't charged and ultimately kept his job.
"It was very difficult to do," Davis said. "But I did it."
In addition to targeting officers who witness force and don't report it, he said, organizations should also go after senior officers who fail to act on complaints.
But those who support duty-to-intervene-related policies, such as Shalom, counter that it puts incentives in the right place.
Shalom said he agreed with Davis that "as a matter of general morality" people have a duty to intervene but that if it's not an explicit job requirement, police officers can't be held responsible for failing to do so.
"They might be morally culpable," he said. "But the position we would find ourselves in if we didn't have that baked into a use-of-force policy or some departmental policy is that you could have an instance where an officer failed to intervene when they clearly should have, where the department sought to take disciplinary action against the officer for their failure to protect someone they were sworn to protect, and they wouldn't be able to because the officer didn't violate policy."
There is some precedent for the recent spate of laws.
Scott Thomson, who was the police chief in Camden, New Jersey, from 2008 to 2019, included a duty to intervene in a new use-of-force policy he put forth for his officers in 2019 with the help of the Policing Project. It was vetted by and earned the support of the ACLU in New Jersey.
For such policies to be effective, they must have teeth, said Parker, an expert on use-of-force law and policy.
"Agency policies and state laws should require that agencies impose discipline, up to and including termination of employment, on officers who violate the duty to intervene or report excessive force," he said. "States should also consider making it a misdemeanor crime for an officer who knows or is aware of a substantial risk that another officer is using or is about to use excessive force and fails to intervene despite having the ability and opportunity to do so safely."
Parker and Shalom said that for such policies to work, officers need to be trained in when they need to intervene and what constitutes excessive force; otherwise the duty to intervene could be quite limited.