"Black Lives Matter represents a trend that goes beyond the decentralization that existed within the Civil Rights Movement," says Aldon Morris, a sociologist at Northwestern University who was not involved in the new study. "The question becomes, 'Are Black Lives Matter protests having any real effect in terms of generating change?' The data show very clearly that where you had Black Lives Matter protests, killing of people by the police decreased. It's inescapable from this study that protest matters--that it can generate change."

The study, published in February as an online preprint item on the Social Science Research Network, is the first of its kind to measure possible correlation between BLM and police homicide numbers. It found that municipalities where BLM protests have been held experienced as much as a 20 percent decrease in killings by police, resulting in an estimated 300 fewer deaths nationwide in 2014-2019. The occurrence of local protests increased the likelihood of police departments adopting body-worn cameras and community-policing initiatives, the study also found. Many cities with larger and more-frequent BLM protests experienced greater declines in police homicides. [...]

Pulley says the Black Lives Matter movement can take some satisfaction in its possible impact on police homicides. "We should use that knowledge to know that the work we're engaged in--the movement, the advocacy, the organizing--is what we need," she says. "And that needs to expand and get broader, so we can join much of the rest of the world in having zero police killings. We can get there. That takes continued and persistent organizing."