WASHINGTON » The murder charges filed on Tuesday against a white police officer shown in a video shooting and killing an apparently unarmed black man as he fled have raised a question about policing that not even the Justice Department can answer: How often do officers across the country fire their weapons?

Under current federal laws, there is nothing requiring any of the 18,000 police departments and other law enforcement agencies across the country to report to the public or to the Justice Department anything about shootings involving officers.

Roughly 91 percent of departments and agencies in the country voluntarily report crimes like murders, rapes, car thefts and burglaries to the FBI, which releases an annual report.

But under the current reporting systems there is no category for episodes in which the officer’s use of force was not deemed legally justified, and there is no category to report police shootings in which the officer has not killed a person. There are categories for "justifiable" or "excusable" homicides by officers, ones in which a felon has been killed by a police officer.

The National Law Enforcement Officers Memorial Fund keeps data on how often people shoot police officers, and departments willingly share that data. But the statistics on the police shooting people are much harder to find.

In the aftermath of the police using lethal force in Staten Island, New York; Ferguson, Missouri; and elsewhere last year, Attorney General Eric H. Holder Jr. and FBI Director James B. Comey have strongly advocated changing reporting requirements. A White House task force created to look into the episodes made similar recommendations in a report released in March.

So far, though, those efforts have not provoked much interest on Capitol Hill, where lawmakers would most likely need to pass legislation to require departments and agencies to report figures to the Justice Department.

In January, Holder spoke about the issue at a Justice Department ceremony honoring the Rev. Martin Luther King Jr. in Washington.

"I’ve heard from a number of people who have called on policymakers to ensure better record-keeping on injuries and deaths that occur at the hands of police," he said. "I’ve also spoken with law enforcement leaders — including the leadership of the Fraternal Order of Police — who have urged elected officials to consider strategies for collecting better data on officer fatalities. Today, my response to these legitimate concerns is simple: We need to do both."

Holder said that in the 1990s, Congress passed a law that was intended to help the Justice Department collect better statistics about shootings involving officers. But that law was ultimately not effective because the reporting was optional, and the local departments and agencies may not have the proper resources to be able to make reports to the Justice Department in a timely manner.

In a speech in February about the relationship between the police and minorities, Comey said that during the riots in Ferguson last summer, he had asked his staff members for figures on the number of blacks who had been shot by the police. They told him there were no uniform statistics on such shootings.

"They couldn’t give it to me, and it wasn’t their fault," Comey said.

Comey said that law enforcement officials and minorities "must find ways to see each other more clearly." He said, "And part of that has to involve collecting and sharing better information about encounters between police and citizens, especially violent encounters."

Comey said that he had spoken with the police chief in a major American city who said that he did not know whether the Ferguson police "shot one person a week, one a year, or one a century."

In the absence of good data, Comey said the police chief told him, "all we get are ideological thunderbolts, when what we need are ideological agnostics who use information to try to solve problems."

Chuck Wexler, the head of the Police Executive Research Forum in Washington, said it was important to track the use of force in general to determine when officers chose less lethal options such as stun guns, and when they calmed tense situations and avoided using force altogether. He said that while many police chiefs may not immediately like the public scrutiny that would come from shooting figures, it would help officials identify trends and see how other departments handled similar situations.

"Police should be reporting this voluntarily until the government catches up," he said.

Compiling that data is one of the first things the Justice Department does when it investigates a police department for civil rights abuses. "It’s better to have this information on the front end, and be able to look at it, than to have DOJ investigate and look at it then," Wexler said.

According to the FBI’s most recent national crime report — the 2013 Crime in the United States Publication — there were 461 justifiable homicides by law enforcement officers in 2013. There were 426 in 2012, 404 in 2011, 397 in 2010 and 414 in 2009.

In an attempt to get a fuller picture of police shootings, the FBI is trying to persuade departments and agencies to use a more sophisticated reporting application — the National Incident Based Reporting System — to log their data. The system is used by a third of the departments and agencies that report data to the FBI and requires many more pieces of data — like when and where the crime occurred and the makeup of the victim.

A board that provides recommendations to the FBI is expected to vote this year on whether to recommend to Comey that departments be asked to report the number of times their officers fire their weapons.

Michael S. Schmidt, New York Times