The Ferguson thing brought this back to my frontal lobes.
It was about 15 years ago, I was a patrol officer, with about seven years on the job, and I spotted a car moving faster than the posted speed limit. It wasn't outrageous, but enough to catch my attention. I pulled said car over. My intention was nothing more to issue a verbal warning. I'd done this countless times before. As I approched the driver's side door, I could see the driver was an elderly African-American man. His wife was beside him. The look in their eyes was a look of pure terror. I'd never seen that look in the eyes of any white person I'd pulled over. These two very nice people, who made a minor transgression, were terrified of me. Where do you think that comes from?? I issued my warning, but the facial expressions of those two people stick with me. I really think they thought I would at best, haul them off to prison, or at worst, kill them. My intention was nothing more than "hey, slow down! I don't want to see you get hurt." End of story: Verbal warning issued, look of huge relief on faces of driver and wife.
I need to keep this in mind.