When the video begins, all you hear is yelling. “It was just a cigarette! Mister, it’s just a cigarette, sir!” The video focuses, and you see a plainclothes police officer holding 17-year-old Marcel Hamer to the gutter with his foot. He bends down, punches the man in the head, and tries to arrest him. “Do you wanna get fucked up?” the office says, “Yeah, get it on film,” he continues. At this point, the young man is unconscious and unresponsive, and his friends are still shouting, screaming that he’s knocked out, begging him to get up.

This footage—taken on June 4—comes from New York City, and follows video of a similar incident from August in a nearby neighborhood, where an officer pistol-whipped an unarmed 16-year-old for briefly running away from police.

But there’s an important difference between the two videos. In the second, we see a familiar scene: black youth, white cops. The first, on the other hand, shows something less common: a black youth and a black cop.

In the aftermath of the shooting in Ferguson, Missouri, where Michael Brown—a black teenager—was killed by Darren Wilson, a white police officer, we learned that Ferguson Police Department was nearly 95 percent white in a town where blacks were the large majority. Residents wanted change. “We want answers, we want justice in our community, we want diversity,” said Rev. Derrick Robinson in one of the early protests.

On the last point, at least, Ferguson city leaders agreed. “We hire everyone that we can get,” said Mayor James Knowles when asked about police diversity. “There’s also the problem that a lot of young African-American people don’t want to go into law enforcement. They already have this disconnect with law enforcement, so if we find people who want to go into law enforcement who are African-American we’re all over it because we want them to help us bridge the gap.” Likewise, during one forum, Ferguson police chief Thomas Jackson said, “The perception is if we don’t have the diversity, we don’t have the understanding, and perception is reality.”

But there’s a problem. For as much as police diversity has value for image and community relations, it’s not clear that it does anything to cure the problem of police abuse and brutality in black and Latino communities. Just because an officer is black, in other words, doesn’t mean he’s less likely to use violence against black citizens.

The best look at this comes from Brad W. Smith, a researcher from Wayne State University in Detroit. In a 2003 paper, he looks at the impact of police diversity on officer-involved homicides in cities of more than 100,000 residents and cities of more than 250,000 residents. Regardless of city size, there wasn’t a relationship between racial representation and police killings—officer diversity didn’t mean much. At most, in smaller cities, female officers were more likely to commit shootings than their male counterparts, a fact—he speculates—that could be tied to sexist pressures on female officers, who might feel the need to act “tough” to prove their bona fides.

What mattered for police shootings wasn’t the makeup of the police department, it was the makeup of the city. In all measured cities, an increase in black residents brought an increase in police shootings. In smaller cities, a substantial change in the proportion of black residents resulted in a slight increase in the predicted number of police-caused homicides. And in the larger cities, the same change increased the chance for police-caused homicides by a factor of 10 compared to smaller cities. Put another way, the quickest way to predict the number of police shootings in a city is to see how many blacks live there.

And, in turn, the most likely victims of fatal police shootings are young black males. According to a ProPublica analysis of federal data on police shootings, young black males ages 15 to 19 are 21 times more likely to be shot and killed by police than their white counterparts. “One way of appreciating that stark disparity,” notes ProPublica, “is to calculate how many more whites over those three years would have had to have been killed for them to have been at equal risk. The number is jarring—185, more than one per week.” What’s most relevant for the diversity of police departments is this fact: While black officers are involved in just 10 percent of police shootings, 78 percent of those they kill are black.

The glib response to stats on blacks and police is to cite so-called “black crime” or “black criminality.” But this depends on a major analytical error. Yes, blacks are overrepresented in arrest and conviction rates. At the same time, “criminal blacks” are a tiny, unrepresentative fraction of all black Americans. If you walked into a group of 1,000 randomly selected blacks, the vast majority—upward of 998—would never have had anything to do with violent crime. To generalize from the two is to confuse the specific (how blacks are represented among criminals) with the general (how criminals are represented among blacks). Statisticians call this a “base rate error,” and you should try to avoid it.

In fairness, you could apply this to police as well. The number of cops who shoot—much less shoot black Americans—is a small percentage of all cops. Why judge the whole by the actions of a few?

But there are problems here. Policing is a profession backed by the state and imbued with the right—and reasonable latitude—to use lethal force. Even if we’re looking at a small number of cops, it’s still a serious problem when those who shoot are most likely to kill people from a specific group. Moreover, the problem of blacks and police goes beyond shootings to general interactions between black communities and law enforcement. We know, for instance, that officers are more likely to use force against black protesters than white ones. The stats on shooting are just one part of a larger dynamic that applies to police departments across the country, not just individual cops.

The history of American policing is tied tightly to its relationship with black Americans and other minorities. The earliest police antecedents were slave patrols and anti-native militias, built to suppress rebellion and combat Native Americans. After the Civil War, Southern whites used police as a new tool for control, terrorizing blacks under the guise of law enforcement, from lynchings—often organized or supported by local sheriffs—to convict leasing. Elsewhere, in the industrial cities of the Northeast and Midwest, policing became a pathway for immigrant mobility. At the same time, police attention turned to black migrants, who were condemned as lazy and criminal. As historian Khalil Gibran Muhammad describes, police during the New York race riots of 1900 and 1905 “abdicated their responsibility to dispense color-blind service and protection, resulting in … indiscriminate mass arrests of blacks attacked by white mobs.”

The antagonism between blacks and police would continue through the 20th century. As BuzzFeed’s Adam Serwer notes in an essay on Ferguson, the urban riots of the 1960s—and beyond—were fueled by police abuse, “The recipe for urban riots since 1935 is remarkably consistent and the ingredients are almost always the same: An impoverished and politically disempowered black population refused full American citizenship, a heavy-handed and overwhelmingly white police force, a generous amount of neglect, and frequently, the loss of black life at the hands of the police.” For a more vivid picture, there’s James Baldwin’s 1960 essay on Harlem—“Fifth Avenue, Uptown”—where he describes the meaning of the white policeman in the black ghetto:

They represent the force of the white world, and that world’s real intentions are, simply, for that world’s criminal profit and ease, to keep the black man corralled up here, in his place. The badge, the gun in the holster, and the swinging club make vivid what will happen should his rebellion become overt.

This isn’t ancillary to the present question of diversity and policing, it’s vital. The culture of policing evolved in a context of racial discrimination and racial control, where departments were charged with containing blacks, not protecting them. The demographics of policing have changed since the middle of the 20th century, but the culture has moved more slowly. And while we have minority officers, they—like their white counterparts—operate in an atmosphere of suspicion and distrust between communities and law enforcement.

“Regardless of who is carrying out the police function,” writes Brad Smith, explaining his results, “police will always be seen as representatives of the larger establishment. As such, tensions between police and citizens may be a function of the police role.”

Over the weekend, activists launched renewed protests in Ferguson and St. Louis. Thousands of people marched for Michael Brown, demanding justice for the slain teenager. On the other side were scores of police, prepared to make arrests if necessary. And in both groups—police and protesters—there were black Americans. From a distance, it’s hard to tell if this mattered for people on the ground, but my hunch is it didn’t. We want to believe that diversity can transform the relationship of police to the communities they serve. But odds are good that it doesn’t, and it won’t. Given the fraught history of blacks and law enforcement, blue—it seems—is the only color that matters.

