The Metropolitan Police Force in London, UK has come under a lot of fire of late because of racism in the force. One particular senior chief commissioner was over looked for promotion on what he claims is at least 3 times. Now I sympathise with anyone being overlooked in any form of promotion, and when this has happened to me I have simply left the company and gone elsewhere.
This particular police commissioner was from an ethnic minority. He, I sincerely hope so, was employed on his merits not because the Metropolitan Police had ethnic quotas to fill to keep the the Equalities Boards happy.
But because of this problem surely then that highlights (a) there is racism in the police force as there are in all walks of life (b) that meeting ethnic minority quotas doesnt actually work, that racial equality in the police force isnt working, so it should be abandoned for something that did/does.
I suspect that police forces might be one of the few exceptions: if the public don't perceive the police as being people like them, members of their community, then it makes the "us and them" situation far worse.
Beyond that, I'm not sure I can offer a solution. I'm not even certain that this effect is significant, given the growing alienation between police and policed in the UK.