And it doesn't matter who "caused" the incident.   The only crucial point is the arrest. And I have not seen one post from anyone which justifies the arrest, and it's rather obvious who carried out the arrest. And it was not Professor Gates.

But please feel free to tell us why the arrest was justified. Please be sure of course to put your argument in the framework of Massachusetts law, since if you were Sgt Crowley, that's where you would have to defend it.