This is going to be a long "answer" that doesn't really answer the question; it just raises more questions.
The simplest and most common answers are in opposition to each other; the first is that white racism is the primary cause for every bad thing that happens in the black community, and the other is that due to culture conflict reasons, black folks distrust and therefore don't join the police, leading to a cycle of culture conflict. Both answers neglect a host of other contributing factors that have neither been fully addressed or measured.
1. Racism - Statistically speaking, racism has to have some affect on racial relations. From my own experience, I know that there are white people with racist views of blacks (and vice versa, and Hispanics with racist views of both whites, and blacks, and vice versa). In this situation, though, the question is how much affect the racism of white folks affects the opportunities of black folks, with a corollary question is how much black folks perceive racism to have such an affect.
For example, at one point in my life, I marketed pizza coupons door-to-door (meaning that I put them on the door, and moved on). More than once, I would walk across the street to avoid talking to a black person. Was this racist? No, because I always crossed the street to avoid social contact with all people I encountered, as I was dysfuntcionally shy at the time. But how many of the people that I avoided had the perception that I did so because they were black?
2. Culture conflict - There are several versions of culture conflict that can be in play here, but I will simplify to the major ones. Middle class culture is the culture which primarily define our mala prohibita laws. Drug use in some minority cultures is not the same as it is in middle lass/lower upper middle class culture.The legal status of drug use/possession is what drives a large percentage of police/minority contact ( and thus arrest and use of force incidents). On the other hand, a "snitches get stitches" view of police interaction, and the accusation of "acting white" for blacks that attempt to succeed on the terms of middle class values also play into culture conflict. I am unaware of studies which measure these factors in regards to racial relations.
3.Police socialization - Policemen have certainly committed racist acts in the past. The acceptance of these acts was part of the police culture. Things have changed to some point, partly due to diversity within police forces. Mark Baker's Cops, compiled in the mid/late 80's, was a collection of monologues by policemen discussing police work, returns over and over again to some policemens' perceptions of race and the changing view of policemen towards racial relations. In turn, a history of police abuses will certainly affect the perception of police by minority cultures, whether or not current practice is still racist. There have been examples of continued discrimination within some departments. The question here is how many policemen are racist, and how many allow racism to affect professionalism.
4. Profiling - Profiling can be a valuable law enforcement tool. How profiling is conducted can be a matter of debate. Profiling can be considered as "racial profiling" when race or ethnicity is either used or perceived to be used as a basis for the stop; Reiman suggests that "terms of the deﬁnition
are satisﬁed if race is used in addition to other factors such as behavior" (Reiman, 2011, p.4). This can increase the negative perception that minority communities hold of the police. If the police stop minority suspects based on the wearing of certain clothes, is the stop based upon those clothes being gang colors, or of a style worn by gang members? If the clothes are of a certain style, is it non-gang members following fashion set by gang members, or vice versa?
5. Anti-police propaganda - Both the Washington Post and the New York Times recently admitted that "hands up, don't shoot" was a lie. Of course, this admission was not on the same front pages that months of the lie were repeated over and over, nor was the lie admitted to until after several businesses had been destroyed in the riots. In Austin, the main newspaper ran a headline "Police shoot unarmed black man in the back twice", notwithstanding the autopsy report that showed the wounds were in the suspect's side, not back, nor that the suspect's gun was dropped close to his body during the pursuit/shooting. 90% of journalists identify as Democrats. I will return to this point.
6. Sabotage of the black community - Policies undertaken with the public justification of improving conditions in the black community have the opposite effect. Ebonics and the new policy of not disciplining problem students do nothing to raise the educational level of underprivileged students. Higher minimum wages result in fewer jobs. As a side issue, there is little study done about the positive effects that churches in minority communities have on people in those communities.
7. Political Opportunism - There is a term for the Jews that fed other Jews into the Nazi's ovens in the concentration camps in order to live a little longer. This term is "Sonderkommando". The Democratic Party needs to recieve from 85% to 90% (depending on location) of the black vote to win elections. Considering that Democrats control the cities and locales where black poverty rates are the greatest and arrest rates for black folks are the highest, that Democrats control the educational systems and unions that are tasked for education in the communities, and that Democratic influence in the media that dominates public discourse has a single narrative supporting policies that do not work, is it possible that the "Sonderkommando" term has a parallel meaning?
Of course, even the theory that the Democratic Party sabotages the black community for the purpose of maintaining a stable voting count can not be the only factor in the conditions that drive racial conditions in this country. Each possible factor must be examined as fully as possible. Some are impossible to quantify. For an example, if a policeman holds both racist and professional values, and has the self-control necessary to conduct his job professionally, how would we measure the effect of his racism...at a value of 0 because he is not acting on racist impulse, or at a 10 for being a racist at all? Racism (and the issues that relate to it) is a hard subject to tackle, not just because many of the factors are hard to objectively measure, but because the issue of race is a very personal and emotional matter. No white person wants to be a priori as racist, no black person wants to be judged a priori as criminal. No cops wants to be judged a priori as a thug with a badge. In fact, no person at all wants to be judged by the actions of others.
Baker, M. (1989). Cops: Their lives in their own words. New York, NY. Pocket Books.
Another factor in Johnson's decision to ignore the Kerner Report was the vast amount of money that he was spending on the Great Society.
To be upfront, I have an ideological bias of my own, in that I don't believe that social spending has long term benefits for the communities it is directed towards. Keeping that in mind, my assumption was that the Great Society was already dumping huge amounts of money on underprivileged communities. Returning to our organizational planning course, it seems that there was no assessment of the impact that these Great Society programs were having before requesting additional spending.