The study, posted in February as an online preprint item on the Social Science Research Network, is the first of its kind to measure a 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.
The study involved a quantitative research technique called “difference in differences,” which mimics a controlled experiment with observational data. Difference-in-differences studies use variation in the timing and location of a “treatment variable” (such as BLM protests or police killings) to sort data into artificial control groups and treatment groups; researchers can then compare an event’s apparent effects in different settings or time periods. The new study compared police killings in cities that experienced BLM protests with those that did not.
“It’s really difficult to measure Black Lives Matter protests and lethal use of force by the police,” notes the study’s author, Travis Campbell, an economist at the University of Massachusetts Amherst. This is mainly because comprehensive data on police killings are lacking: the federal government does not track police officers’ lethal use of force, and media and grassroots organizations attempt to fill the void via Freedom of Information Act requests and crowdsourcing efforts.
Aislinn Pulley is a co-founder of Black Lives Matter Chicago, which has compiled a list of everyone who died at the hands of the Chicago Police Department since 2011. “It’s extraordinarily important to have concrete data of the numbers of incidents that involve police violence of all stripes, from killings to torture to being held incommunicado in police stations to people who died in custody,” she says. “We didn’t have access to that data prior to the movement—and we still have only partial access.”
Because the national picture of police homicides remains incomplete, “the big issue is that you may undercount the true number of fatal interactions” with police—especially in lower-population areas where media coverage may be lacking—Campbell says. To address this, he gave greater weight to results from larger cities, where he says news reports of police killings and protests likely had more accurate estimates of both. He analyzed the relationship between protests and police homicides using several different techniques and consistently found similar results.
This is also why that even if you don’t think police abolition is realistic, you should still support police abolition. Liberals so often misunderstand the politics of organizing. They want to take a position they think is reasonable and can defend on the policy merits. The problem with that is that this is not how compromises are forged and change made. You take the strongest possible position and realize that you probably won’t get there. It’s highly unlikely that the police will ever be abolished in this nation. But without direct verbal attacks on the police’s right to exist as an institution, there is no real political pressure to force them to change their racist, violent, murderous message. The morals of the issue are far more important than the detailed policy questions of implementation.