Cop killers.

• Author: Shackford, Scott
• Position: Poolice shooting data - Brief article

THE RECENT increase in media attention and public outrage over citizens killed by police has brought an additional problem to light: The United States does not reliably track how frequently such deaths occur. As a result, it's difficult to analyze or report on trends related to deadly uses of force.

The FBI does attempt to track whenever a police officer kills somebody, but participation in the program is voluntary and very spotty. Entire states are left out of the count, such that the FBI's database likely catches at most half of killings by cops: about 400 a year.

Two media outlets, The Washington Post and The Guardian, decided in 2015 to independently track the number of people in America killed by police. The former newspaper reported 983 people fatally shot by police last year. The latter, tracking all killings and not...