Sergeant Oldham is driving through an area well known for drug dealing. He has been a police officer for more than 20 years and is well known for his instincts relating to criminal activity. He sees one young man standing on the corner. Sergeant Oldham has a "gut feeling" that the man is dealing crack. Oldham stops his patrol car two blocks away and watches the man for 20 minutes.

During that time, Oldham observes four separate occasions where one person walks up to the man, hands him something, and then the man gives the person something back. The two people then part ways. Sergeant Oldham also sees the man wave and whistle at passing cars. A couple of the cars pull over, the man leans in the driver's window for a minute or so, then walks away and the car leaves. In his years of experience, Sergeant Oldham believes this man is dealing drugs.

The next time a pedestrian approaches the man, Sergeant Oldham drives his patrol car up to the pair who, upon seeing the officer, start to walk away. Oldham gets out of his squad and orders both of the people to stop. As the man stops and turns around, he drops a baggie containing crack on the sidewalk. The man is arrested.

What facts does the sergeant have to support a stop?

What effect does the sergeant's experience have on the outcome?.