Describe the circumstances under which a law enforcement officer can legally conduct a 'stop and frisk' according to Terry v. Ohio, and what constitutes a permissible scope of a frisk.

According to the Supreme Court case Terry v. Ohio, a law enforcement officer can legally conduct a 'stop and frisk' under specific circumstances. First, the officer must have 'reasonable suspicion', based on specific and articulable facts, that criminal activity is afoot. This means the officer must be able to point to objective facts and rational inferences that lead them to believe that the person they are stopping is, or is about to be, involved in a crime. Second, the officer must have a reasonable belief that the person is armed and dangerous. This belief must also be based on specific and articulable facts, not merely a hunch or generalized suspicion. These two conditions must be met independently; reasonable suspicion of criminal activity does not automatically justify a frisk for weapons. The permissible scope of a 'frisk' under Terry v. Ohio is limited to a pat-down of the outer clothing for weapons. The purpose of the frisk is not to discover evidence of a crime, but to protect the officer and others nearby by ensuring the person is not armed. The officer can only seize an object during the frisk if it feels like a weapon. If, during the pat-down, the officer feels an object whose contour or mass makes its identity as contraband immediately apparent (the 'plain feel' doctrine), the officer may seize that object. However, the officer cannot manipulate the object to determine its identity; the incriminating nature must be immediately apparent without further intrusion. For example, if an officer feels a hard, metal object shaped like a gun during a pat-down, they can seize it. But if they feel a small, soft object in a pocket, they cannot manipulate it to determine if it is drugs unless its identity as drugs is immediately apparent from the initial touch.