Answer to Question 1
A Terry stop/seizure is characterized by two specific events:
(1) The police question a person or communicate with him or her.
(2) A reasonable person would believe that he or she is not free to leave.
Reasonable suspicion is required in order to make a Terry stop conform to Fourth Amendment requirements. Conversely, if an officer detains a person in such a manner that a reasonable person would believe he or she is free to leave, the protections of the Fourth Amendment do not apply, and reasonable suspicion is not required. If the officer wishes to conduct a friska separate act from a stophe or she must have reasonable suspicion that the suspect is armed and dangerous, not just reasonable suspicion, as required for a Terry stop. There are no clear answers as to what is the appropriate duration for a stop. However, as the Supreme Court suggested in United States v. Mendenhall, a lengthy stop is constitutionally permissible when:
(a) the public interest is served by the seizure,
(b) the nature and scope of the intrusion are not excessive, and
(c) the officer possesses enough in the way of objective facts to justify the stop.
Thus, if a person is stopped and detained for a long time based on an officer's hunch but poses no threat to public safety, the stop will probably be declared illegal. In such a situation, the stop would need to be justified by probable cause because it would amount to a de facto arrest.
Answer to Question 2
Unfortunately, there are few clear guidelines as to the appropriate duration of a stop. The Supreme Court has stated that the reasonableness of a stop turns on the facts and circumstances of each case. In particular, the Court has emphasized (1) the public interest served by the seizure, (2) the nature and scope of the intrusion, and (3) the objective facts upon which the law enforcement officer relied in light of his knowledge and expertise (Mendenhall, 446 U.S. 544).