From your article.
“Gates went in through the back with a key, turned off his alarm and, with the driver’s help, forced opened the front door.
By the time police arrived, Gates was inside and the driver who had carried his luggage into the house was gone.
The responding officer, Sgt. James Crowley, asked Gates to step outside of the house. Gates refused. A confrontation followed, and Crowley arrested Gates on a charge of disorderly conduct and led him out of his house in handcuffs.“
Seriously, read the 4th amendment, it protects the citizenry from these types of abuses by the state.