The greatest problem is not 'rotten apples' in the US police force (and the criminal justice system generally). They can be dealt with. It's not just about police. The problem is that the entire criminal justice system is institutionally racist. Police brutality is just one part of a horrifying abuse of human rights. And, yes, I can say that with 20 years worth of dedicating my research to understanding the racialisation of crime and the criminalisation of race in the USA.
For anyone doubting this, read Michelle Alexander's The New Jim Crow. America has 5% of the world's population, but 25% of the world's prisoners.
Goffman's book is very good.
www.ted.com/talks/alice_goffman_college_or_prison_two_destinies_one_blatant_injustice
www.ted.com/talks/bryan_stevenson_we_need_to_talk_about_an_injustice
If you want to understand why black people fear the CJS, watch this: {warning it contains horrific images of lynch victims): withoutsanctuary.org. A picture paints a thousand words. These lynchings were continued through to the mid 20th century. You can see from the fact that people aren't afraid to show their faces that nobody was worried about being arrested. They were able to act with complete impunity. Police, judges, and prison guards were often in the crowd. The belief that police are people to fear, rather than look to for help, is indelibly marked in African American minds.
Rainbunny: as I've said above. No, not every white person is racist. This is not an issue of individuals. It's a problem in American society, politics, and culture. The problem is that white America as a whole refuses to see how the criminal justice system reinforces racial inequality. Race sits at the very core of the American society in a way that many Brits just can not comprehend.
yoursan: for everything I've said, you're wrong. The USA has launched some incredible experiments in political culture and social equality. It has produced some fascinating and amazing people who have dedicated themselves to trying to create a democratic country. It is not, of course, the greatest democracy on earth, but anyone sitting smugly believing that Britain is any better needs to think again.