Taranto's piece is even-handed and fair, but I'd add one (important) thought to this:
This is not to say that the police are always right, and it seems to us that arresting Gates was an unwise use of the officer’s authority. Having ascertained that the burglary report was false, the cop had no reason to remain on the scene. This appears to have been a misunderstanding between two stubborn men, both of whom would be better off had one of them exercised some maturity and forbearance.
The difference is that in encounters between the police and the public, it is the police officer who is being paid to exercise maturity. If a citizen acts less maturely in such an encounter, he is simply behaving poorly. If a police officer acts less maturely, he is doing his job badly. That's a substantial difference.