Quote Originally Posted by lxdude View Post
Actually, you are being "detained".
As I recall from my police days, it was legally classified as an arrest. A police officer is not required, (in the U.S., anyway), to inform people they are talking to in an official capacity that they are under arrest. Police officers can also allow people to go on their way once they are satisfied.

Keep in mind, I am talking about when an officer is officially conducting police business, such as an investigation.