From Police Chiefs Magazine.
Because it is legal in most states to carry a handgun if properly licensed, a report that an individual possesses a handgun, without any additional information suggesting criminal activity, might not create reasonable suspicion that a crime is being or will be committed.1 Where simply carrying a handgun is not in itself illegal and does not constitute probable cause to arrest,2 it follows that carrying a handgun, in and of itself, does not furnish reasonable suspicion justifying a Terry stop. The same applies to persons in motor vehicles. An investigatory stop is only justified when the police have "a reasonable suspicion, based on specific, articulable facts and reasonable inferences there from," that the subject "had committed, was committing, or was about to commit a crime."3