There are conflicting reports as to what occured during the minutes prior to the arrest of professor Henry Louis Gates. 
The Police officer says Gates provided Harvard identification only (which has no address to confirm residence) whereas Gates claims to have shown both a Harvard I.D. and a drivers' license, which does have an address.
Gates says officer Crowley ignored the former's request to state his name and badge number, whereas Crowley claims he did so twice, and refused to do it a third time due to Gates' noise and unnecessary insistence.
Who is telling the truth? I don't know, and you don't know either. There is no video, no audio, or media report of what the witnesses gathered around the site had to say.
It would be ok to take a wild guess and side with one of these two individuals, if their past history revealed patterns of racism (in the case of the cop) or disorderly behavior (in the case of Gates). But no such clues exist. Both individuals seem to have impeccable records.
Unfortunately, the kneejerk reaction by some in the Left is to defend the obvious "liberal" position: the black victim is right, and the white male cop is wrong and racist. The right-most elements of the Right do the same: The white guy is right and the black guy is wrong.
Sometimes it's ok to say "I just don't know." Try it.