Roughly 200 of the nation’s most prominent police chiefs, Justice Department and White House officials, and police training experts convened in Washington on Friday to discuss policy proposals which, if implemented broadly, would amount to the most drastic police reform in decades.

During the forum, titled “Taking Policing to a Higher Standard” and held in the seventh-floor meeting rooms of the Newseum, top officials from many of the nation’s largest police departments were urged to implement new training and departmental policies that supporters believe could lead to a decrease in the number of fatal shootings by officers each year — a topic near the top of the national consciousness in the 18 months since the shooting of Michael Brown in Ferguson, Mo.

“This is a defining moment for us in policing,” Charles Ramsey, the recently-retired commissioner of the Philadelphia Police Department, told the room. Ramsey, also a former D.C. police chief, was one of several prominent policing officials who said departments must act proactively to change their use-of-force policies instead of waiting for one of their officers to be involved in a controversial shooting.

Privately, several of those in attendance remarked that the shift in attitude of top police officials toward reform seems a direct result of the protests in Ferguson, Baltimore, Chicago and elsewhere and the resulting increase in media scrutiny of police use of force.

“We need to raise the bar for all police departments,” said Chuck Wexler, who runs the Police Executive Research Forum, a policing policy think-tank that organized the gathering.

Accurate national statistics on fatal police shootings were unavailable until last year when The Washington Post launched a database to track them, documenting 987 fatal shootings by on-duty officers in 2015.

Wexler presented The Post’s findings to the gathering of officials and said that even after removing all shootings in which the person killed had a gun, there were still hundreds of preventable fatal shootings last year.

“We can impact about 300 of those,” he said.

The goal of reform, organizers said, should be to address the large number of shootings that are “lawful but awful” in that they do not amount to a crime but that they spark community outrage and could have been prevented.

Among reforms discussed at length were retraining all officers in deescalation tactics and abandoning training that teaches the “21-foot-rule” — a turn of phrase taught to nearly all current U.S. police officers that is often interpreted by officers to mean they are justified in shooting any suspect with a knife or edged weapon who comes within 21 feet of them.

“It almost gets to the point that officers are thinking ‘my safety is more important than the safety of anyone else’s’ ….,” said Tom Manger, chief of police in Montgomery County, Md. “We’ve got to change the culture of American policing. … Our goal should be to have everyone go home safely at the end of the day.”

How any department handles an officer-involved shooting or other use of force incident varies depending on the department’s policies, local union contracts and state laws.

In an attempt to address the lack of national standards governing police use of force, Wexler proposed to the chiefs 30 “guiding principles” — which include prioritizing the preservation of human life, adopting deescalation as a formal agency policy, quickly releasing information about any use of force incident, and training officers that it is their duty to intervene to prevent another officer from using excessive force.

“It’s important for us to recognize the gap that exists between what is acceptable in community standards of use of force … and what is acceptable under the law,” said Scott Thomson, chief of the Camden County Police Department in New Jersey.

Currently, almost all fatal police shootings, especially those during which the person killed has a weapon, are ruled legally justified, based in part on the 1989 Supreme Court decision that established the “objectively reasonable” standard. It excuses an officer who perceives a threat that any other objectionably reasonable officer would perceive, even if the shooting itself violates policies or protocols or the threat turns out to not exist.

“There is a real mismatch between what community standards are, what the community expects, what they think the law should be, versus what the training and the law allows for,” said Vanita Gupta, Department of Justice’s assistant attorney general for civil rights. Gupta said a national conversation about police objective reasonableness was potentially “revolutionary.”

One provision that drew significant discussion and push-back among the chiefs was a policy guideline calling for all police use of force to meet a proportionality standard, which called for officers to consider how the general public might view any use of force in determining whether it is appropriate.

Several of the chiefs noted that they anticipate, or have already seen, significant resistance from their officers and local police unions to an attempt to change policies or to hold officers more accountable. Milwaukee Police Chief Edward Flynn, who said that officers need to be disciplined more consistently for violating policing policy, recalled the anger he provoked with his decision to fire the police officer who shot and killed Dontre Hamilton, a mentally ill man who was asleep on a park bench.

While the shooting was not criminal, Flynn said, the actions of former officer Christopher Manney violated department protocol.

“I made a decision to fire him and announced it at a press conference in which I still defended his use of deadly force at that instant,” Flynn said. “As you can imagine, that decision wasn’t meant to please anybody, and succeeded.”

“I had the Coalition for Justice demand my firing, and the police union vote no confidence,” Flynn said, prompting a round of laughter. “And I like to think at that moment I kind of brought the police and community together.”

Others questioned whether departments should train their officers that they are accountable for their behavior above and beyond the “objective reasonableness” standard. Instead, some of the chiefs said, through retraining, the culture of policing could up the standard for what would be deemed “objectionably reasonable.”

“I’m totally in agreement that police don’t know how to retreat in the United States and that we kill too many people. There are things that we can do … to reduce the death toll,” said Ed Davis, the former Boston police commissioner. “However, when we get to this point where we start to say that we have to hold ourselves to a higher standard, it’s great rhetoric but … it’s difficult for an agency to say ‘even though the Supreme Court said this, we’re gonna say that.’ ”

The group watched a number of videos — taken by bystanders and body cameras — of police shootings that occurred in 2015, as well as other videos of police behavior that went viral, such as the video of an officer breaking up a pool party of teenagers in McKinney, Tex.

“I’m surprised you haven’t shown my video yet,” said Daniel Oates, the police chief in Miami Beach, where in December officers killed an alleged bank robber wielding a straight-edge razor in a shooting caught on camera.

Moments later, the chiefs were dissecting the video of the Miami Beach shooting, during which officers surround the man, 51-year-old David Winesett. One officer gets close enough to deploy a stun gun and as he does, another officer opens fire.

“I’ve learned that South Florida doesn’t have the longer, less lethal weapons,” Oates said, adding that he wishes one of the officers responding to the man had had a gun that could fire less lethal ammunition, such as a beanbag. “I’m kicking myself. I had been there 18 months and I hadn’t inquired into it. In my last agency we used less lethal shotguns very effectively.”

They also watched videos from Scotland and Northern Ireland, where police kill very few people despite often facing violent threats — in part, the chiefs said, because their officers are trained to back away from potential threats and retreat if necessary.

“In America, police officers do not have an obligation to retreat,” noted William McManus, chief of the San Antonio Police Department. “That is problematic.”

Other chiefs noted that they were initially skeptical of some of the proposed reforms, only to later see their merits after some of the changes were implemented.

Among the suggestions were that departments implement a policy that prohibits officers from shooting into a moving vehicle — a step taken by the New York Police Department in 1972 that drastically cut down on the department’s number of fatal shootings.

The Denver Police Department has had several fatal shootings involving people in cars in recent years, including the death of 17-year-old Jessie Hernandez. That prompted Wexler to call the Denver police chief and recommend he research the NYPD’s policy.

“I’m saying ‘that’s kind of stupid’… is what I said to myself … but at the same time I realized that we needed to do something different,” said R.C. White, Denver’s police chief.

After researching the departmental policies of other police units, White chose to craft a new policy banning officers from shooting into a moving vehicle and providing his officers with more training in how to get out of the way of a suspect in a vehicle.

“We ended up changing our policy,” White said.