Why Are So Many Police Killings Not in FBI Data?

The August shooting death of 18-year-old Michael Brown in Ferguson, Mo., sparked a national discussion about killings by police officers. Yet it is nearly impossible to answer the question: How many such killings occur every year in the U.S.? According to a page-one article and related graphic in The Wall Street Journal, there are hundreds more such deaths than accounted for in federal statistics.

How did the Journal determine that some police killings are unaccounted for?

Reports of justifiable homicides by law enforcement are provided to the FBI each year. A Journal analysis of the latest data from 105 of the country’s largest police agencies found more than 550 police killings between 2007 and 2012 were missing from the national tally or, in a few dozen cases, not attributed to the agency involved.

Why are so many police killings not in the FBI data?

The reasons are numerous. Reporting such information to the FBI is voluntary, and some agencies don’t do it. About a dozen agencies said their police-homicide tallies didn’t match the FBI’s because of a quirk in the reporting requirements: Incidents are supposed to be reported by the jurisdiction where the event occurred, even if the officer involved was from elsewhere. Also missing from the FBI data are killings involving federal officers.

Does the Journal’s tally tell us how many justifiable homicides occurred throughout the U.S. from 2007 to 2012?

No. The Journal collected data on justifiable homicides from the largest police departments. That information is in an interactive here. But there are many more police agencies not included. In the period examined, 753 police entities reported about 2,400 such killings.

Why does it matter that the statistics are incomplete?

Law-enforcement experts have long decried the lack of national data on police killings. Some police departments say more comprehensive numbers are useful in policing. Paco Balderrama, a spokesman for the Oklahoma City Police Department, said that police can use data to improve tactics, particularly when dealing with the mentally ill.