I found this in Slate today. It is interesting he makes exactly the same point I was making earlier, although he says it so much better....

More recently, I was walking at night in the wooded California suburb where I spend the summer, trying to think about an essay I was writing. Suddenly, a police cruiser was growling quietly next to me and shining a light. "What are you doing?" I don't know quite what it was—I'd been bored and delayed that week at airport security—but I abruptly decided that I was in no mood, so I responded, "Who wants to know?" and continued walking. "Where do you live?" said the voice. "None of your business," said I. "What's under your jacket?" "What's your probable cause for asking?" I was now almost intoxicated by my mere possession of constitutional rights. There was a pause, and then the cop asked almost pleadingly how he was to know if I was an intruder or burglar, or not. "You can't know that," I said. "It's for me to know and for you to find out. I hope you can come up with probable cause." The car gurgled alongside me for a bit and then pulled away. No doubt the driver then ran some sort of check, but he didn't come back.

In the first instance, I found again what everyone knows, which is that there are a lot of warped misfits and inadequates who are somehow allowed to join the police force. In the second instance, I found that a good cop even at dead of night can and will use his judgment, even if the "suspect" is being a slight pain in the ass. But seriously, do you think I could have pulled the second act, or would even have tried it, or been given the chance to try it, if I had been black?

It is not surprising it is said so much better, I just realized Hitchens is the author. However, after reading it again, I don't think "warped misfits and inadequates" is the correct way to describe those he is speaking of, I think that many of them surely have those tendencies before they join, and those tendencies push them in the direction of law enforcement, but I don't think these qualities really come out until they are subjected to the line of work. They deal with the miscreants of society, and, as I said before, are subject to more than their share of respect and submissive people, so much so that their world view becomes skewed. The cop in the scenario above knew where to draw the line, but the observation that the skin color of the pedestrian may have clouded his thinking, and the line would have blurred somewhat.

That is his point. Hitchens wasn't harassed further possibly because he was white. A black pedestrian doesn't have that luxury, and the chances of continued harassment in that case would be good, even if he responded to the cop's inquiries in exactly the same manner.