As he approached the house, Sgt. Crowley did not know that Prof. Gates, who was inside, had had trouble getting into his own front door, and that's why he had been reported by a passerby as trying to force entry; he did not know that Gates had just arrived home from a business trip in China and was fatigued and inconvenienced by the stuck front door; he did not know that Gates was a renowned Harvard professor and not a criminal.
What is known about Crowley? In an interview with WEEI radio in Boston on July 23, the sergeant explained that it was for his own safety as a police officer and father that he first asked Gates to step outside, as mid-day burglaries are not uncommon in that area. He didn't think the neatly dressed Gates looked like a burglar, but perhaps Gates might be unaware of an intruder in the home.
But this is all after the fact. In the heat of the moment, when people don't know anything about each other, it's easy to make assumptions based on personal or cultural experience.
From Gates's account, Crowley is guilty of racial profiling – of assuming that Gates is a suspect simply because he's black.
The professor assumes that Crowley is a racist white cop, demanding identification even after being told by Gates that he lived there and worked at Harvard, then following Gates into his kitchen as he retrieved identification. Crowley, says Gates, refused to give his name and badge number (Crowley countered today that he gave his name twice; and then when he was reaching to get his own ID, Gates turned and walked to the kitchen).
"Is this how you treat a black man in America?" Gates says he asked repeatedly, as he followed the officer out the front door, then was arrested for disorderly conduct – despite multiple warnings of arrest if he did not calm down.