Considering the Sgt. Crowley - Henry Gates situation.
Many (many, many) years ago I was driving home after one of those endless Sierra Club Executive Committee meetings. It was after midnight, I was hungry and tired, and I was less than interested in the legal speed limit. A Highway Patrolman's lights flashed behind me and I pulled off the freeway to take my speeding ticket.
Rather than ticket me, the cop tried to goad me to anger. While outwardly calm, the cop threatened me. He threatened to handcuff me, he threatened to arrest me. Not physically but verbally he was pushed me hard, trying to get me to react, to defend myself. If I had I would have found myself face down on the pavement with his knee on my back.
Had I gotten scared or angry I would have spent the rest of the night in jail. I used the same techniques needed for facing a vicious dog; I can't claim that as a deliberate strategy, it was an instinctive reaction. I looked the cop in the eye, remained calm, and displayed neither aggression nor retreat. After about ten minutes the cop backed down and left without even writing a speeding ticket.
The difference between my encounter with the police and Mr. Gates' is: 1) I'm white; 2) I didn't react when the policeman tried to goad me into a confrontation. I am certain that it took both conditions to keep me out of jail that night.
Like my encounter years ago, I believe Sgt. Crowley was pushing Gates, trying to induce a fear/defense response that would justify an arrest. It is a common police technique taught at the academies. Crowley wanted the encounter to end in an arrest. A simple test whether race was involved is whether Crowley, in his long career as a police officer, has ever arrested a white man in circumstances similar to those of Mr. Gates. I suspect probably not.