Black Americans are less likely to dial 911 immediately following, and for more than a year after the highly publicized assault or death of a black person at the hands of police. That’s the conclusion in “Police Violence and Citizen Crime Reporting in the Black Community,” a study to be published in October’s American Sociological Review, the official publication of the American Sociological Association.

Three sociologists—Matthew Desmond at Harvard, Andrew Papachristos at Yale, and David Kirk at Oxford—screened and analyzed over 1.1 million 911 calls made to Milwaukee’s emergency dispatch between March 1, 2004 and December 31, 2010. They isolated and further analyzed some 883,000 calls in which a crime was reported within city limits in black, Latino, and white neighborhoods where at least 65 percent of residents fit the race category, per 2000 Census data. They chose those dates in order to study what, if any, impact the brutal beating of Frank Jude by several police officers might have had on residents dialing 911 for help. The effect they found was significant.

“Police misconduct can powerfully suppress one of the most basic forms of civic engagement: calling 911 for matters of personal and public safety,” the authors wrote in the study. The author’s conclusions may also shed some light on the controversial “Ferguson effect,” that is, the idea that a rise in crime follows a high-profile incident of police brutality.

The study makes for a grim chronicle. On October 23, 2004, Jude and a black male friend arrived at a private party in a white middle-class neighborhood as guests of two white women college students. Shortly after arriving, the four headed to their vehicle, but it was soon surrounded by at least 10 men.

The men  accused Jude and his friend of stealing Andrew Spengler’s police badge, and all four were pulled from their truck. Jude’s male friend had “his face slit with a knife” and escaped, according to the authors. Jude suffered blows to his face and torso; his arms were pinned behind his back; he was kicked in the head; an officer stomped on his face “until he heard bones breaking;” he was picked up and kicked in the groin so hard “his feet left the ground;” he had a pen inserted deep into his ear canals; his fingers were “bent back” until “they snapped;” before finally being left naked from the waist down on the sidewalk in a pool of his own blood.

Jude’s story would not become public until months later when the Milwaukee Journal Sentinel published a report on the incident on February 6, 2005, and recounted the police cover-up that had followed. Black residents protested almost immediately, demanding action from the district attorney. A month later, nine officers were dismissed. Spengler and two others were tried and acquitted by an all-white jury. Protests ensued again. A federal investigation led to the conviction of seven of the officers involved.

“Once the story of Frank Jude’s beating appeared in the press, Milwaukee residents, especially people in black neighborhoods, were less likely to call the police, including to report violent crime,” David Kirk, one of the authors of the report, said in a statement. “This means that publicized cases of police violence can have a communitywide impact on crime reporting that transcends individual encounters.”

A total of 22,200 fewer calls were made to 911 during the year following Jude’s beating, according to the researchers, with over half of that loss (56 percent) happening in black neighborhoods. The authors of the study see the significant decline as worrisome given how heavily police work depends on resident-initiated interactions, such as calling the emergency line. “Police work of every kind relies on citizen participation, especially reports of law breaking … If police misconduct lowers crime reporting throughout black communities, it directly threatens public safety within those communities, many of which already have high levels of crime,” the authors concluded in the article.

To test their theory that police brutality makes black Americans less likely to contact police, the authors also analyzed the impact of other highly publicized incidents of violence against black men by law enforcement, including two that happened outside of Milwaukee. They looked at the killing of Sean Bell in Queens, New York in 2006, the assault of Danyall Simpson in Milwaukee, Wisconsin, in 2007, and the killing of Oscar Grant in Oakland, California in 2009. Of these three, only the latter did not trigger a drop in calls to 911. The data again led to the conclusion that “other local and national cases of police violence against unarmed black men also had an impact on crime reporting in Milwaukee.”

But since suspicion and mistrust of police among black Americans are not new issues,  what do we really learn from the study? A few things.

First, the study established a direct link between police misconduct and the decrease in residents’ participation in ensuring their own safety. “It is one thing to disparage law enforcement in your thoughts and speech after an instance of police violence or corruption makes the news. It is quite another to witness a crime, or even to be victimized, and refuse to report it,” the authors wrote. “The events of that October morning affected not only Frank Jude and his family but Black Milwaukee as a whole.”

The whole-neighborhood effect that led to many people choosing not to call 911 reflects the idea that police lose authority and legitimacy as citizens associate their actions with lawlessness and violence.

Second, MPD’s ability to do their jobs was severely curtailed due to losing over 20,000 emergency calls that could have resulted in the  prevention of serious crimes. “[B]y driving down 911 calls—thwart the suppression of law breaking, obstruct the application of justice, and ultimately make cities as a whole, and the black community in particular, less safe,” the researchers summarized.

In the six months after Jude’s story was published—March through August 2005—87 homicides took place in Milwaukee, adding up to a 32 percent increase in homicides relative to the same six-month period in 2004 and 2006, according to a release from ASA. “In fact, March through August 2005 was the deadliest spring/summer in the seven years that the researchers examined,” the authors said in a statement.

Third, although the death of a resident at the hands of police elicited the biggest drops in 911 calls from black neighborhoods, a death was not always necessary to register a significant drop in such calls. Danyall Simpson’s non-fatal assault set off a drop in calls immediately after it was reported in the local media. The study’s authors offered some insights into the significance of this:

This indicates that high-profile cases of excessive police force constitute a severe breach in the social contract that exists between citizens and the criminal justice system. That breach is so sudden and violent when unarmed black men are beaten or killed that virtually no institutional response, from public apologies to sanctioning offending officers, can swiftly repair it.

Fourth, “the Jude effect”—as the authors have labelled the drop in calls to 911 they documented—appears to be most pronounced in black neighborhoods. Though they also examined neighborhoods that were majority-white and majority-Latino, the researchers determined that they would not expect to see equally significant drops in 911 calls in those neighborhoods because the underlying historic factors are not the same as in black neighborhoods. These factors include: “a centuries-old tradition of state-sanctioned assaults on the black body”; blacks collectively perceiving “an assault of a black man by white police officers as an assault on the black community writ large”; and the acute segregation in Milwaukee.

“Police departments and city politicians often frame a publicized case of police violence as an ‘isolated incident,’” Papachristos said in a statement. He also said that “no act of police violence is an isolated incident, in both cause and consequence. Seemingly isolated incidents of police violence are layered upon a history of unequal policing in cities.”