One of the most striking statistics to emanate from the killing of an unarmed teenager 12 days ago in Ferguson, Mo. is this one:  Only 3 out of 53 police officers are black, in a town that’s two-thirds black.

Why does that seem so concerning? Well, one might reasonably conclude, there’s something deeply awry when law enforcement is so unrepresentative of the community it’s supposed to serve. And it’s not just Ferguson: White people are over-represented in police forces generally, especially in suburban towns where the population had grown increasingly diverse in a period of a decade or two. That’s problematic, theoretically, because it undermines trust between the police and minority communities, which could escalate conflict rather than diffuse it. And it’s why police forces have been pressed to diversify ever since the aftermath of race-related riots in the 1960s.

But do racially-balanced police forces actually treat their communities any more fairly than those as skewed as Ferguson’s?

Some social scientists have taken a look at the racial disparities in the behavior of officers, but the topic is still being studied. And there is hardly any research at all on whether racial disparities exist between officers when they use force. In part, that’s because people of color haven’t been widely represented, even to the extent they are today, for very long in law enforcement. (And for now, black officers have been studied more closely than Latino ones specifically).

From the studies that have been done, however, there’s no conclusive evidence to show that white and black police officers treat suspects differently — if anything, some of the studies show that black officers can be can be harder on black criminal suspects.

From the studies that have been done, however, there’s no conclusive evidence to show that white and black police officers treat suspects differently — if anything, some of the studies show that black officers can be can be harder on black criminal suspects.

In 2004, for instance, criminologists found in an analysis of observational and survey data from St. Petersburg, Fla., and Indianapolis, Ind., that in resolving conflicts, “black officers are more likely to conduct coercive actions” — which could mean anything from verbal orders to physical confinement — than white officers. A 2006 study of Cincinnati police records concluded that white officers were more likely to arrest suspects than black officers overall — but it also found that black officers were significantly more likely to make an arrest when the suspect was black.

What’s more, polls show that black communities do not necessarily trust police forces more when they are more racially representative. In Washington D.C., according to a 2011 Washington Post poll, the police department got a relatively low 60 percent rating from black residents, despite the fact that the force is highly integrated. The New York Police Department’s demographics are close to those of the rest of the city, but a Quinnipiac poll from 2014 found that only 54 percent of black residents approved of its performance. The Detroit police department is so dominated by African Americans that it’s been sued for discrimination against whites, and yet only 18 percent of black Wayne County residents approved of its work in 2009.

To be sure, some of the studies agree diverse police departments have an easier time building bridges with minority communities. The 2004 study showed, for example, that black cops are more likely than white cops to engage in “supportive” actions in black neighborhoods, which suggests that they might have a higher degree of empathy and cultural understanding with communities that look like them. Also, in the police killings where the officer has been identified — which certainly doesn’t yield a complete data set — African American officers are rarely at fault, with the 2006 shooting of Sean Bell as a notable exception.

“Anecdotally, you just don’t hear a lot about people beat up or killed by black officers,” says Ezekiel Edwards, director of the American Civil Liberties Union’s Criminal Law Reform Project, while noting that he didn’t think black officers would be less likely to engage in racial profiling.

Regardless of whether or not you believe that police brutality against people of color stems from racism, it’s clear that actually reforming a police department to make sure it treats people of all races fairly is a more complicated task than adding black and Latino officers, say some researchers as well as advocates focused on the use of force by police. “Not to minimize the importance of diversity,” said Nusrat Choudhury, a staff attorney in the ACLU’s racial justice program, “but it’s not a one-shot solution.”

Tash Nguyen, an organizer with the anti-prison group Sin Barras in southern California, says at times the pressure on minorities to assimilate within police culture tends to overwhelm any racial loyalties that might have existed before.

“There is a sense of security in joining the police force, and being on the ‘protected’ side of the line,” says Nguyen. “If you join the police force because you feel like it’s the only way to protect yourself, that is the cycle that is reproducing itself in the name of public safety.”

Nguyen is currently working with a very tense situation in Salinas, Calif., which has seen four police killings of unarmed Hispanic men since March. The Salinas Police Department hasn’t yet released the names of the officers involved, but the department is 40 percent Hispanic. That’s why, she adds, Hispanic people especially often distrust minority police officers just as much as white ones.

“When brown or black people are being apprehended, and are not speaking or responding to white officers, a Latino officer will always be brought in to negotiate, and seem to speak from a place of empathy when they’re really just conveying the same thing,” Nguyen says. (Read an interview with the Salinas chief of police here).

For many police departments, however, diversity is actually a very new thing, and it’s possible that they haven’t reached the critical mass necessary to actually shift how departments operate. Also, while the rank-and-file may have diversified, leadership remains disproportionately white and male. As one Stanford Law professor wrote, having black people, Latino people, women, and gay people around tends to open up space for discussion and dissent — in a good way. But it takes time for that to percolate, and even longer for relationships to change on the street, says Malik Aziz, chairman of the National Black Police Association.

“The problem becomes with those departments, that they do not have a real community police relationship that is proactive and positive, so chief after chief has failed to gain trust in the communities that distrust them,” says Aziz. “Then you have a collapse like what you’ve seen in Ferguson. Whenever you see a collapse, it’s that you didn’t do the things that take decades to build.”

Peyton Craighill contributed to this report.