Background
Cleveland Detective Martin McFadden watched John Terry and another man repeatedly walk past and look into the same store window, confer, and later meet a third man. Suspecting they were casing a robbery and might be armed, McFadden approached, identified himself, asked their names, and patted down Terry's outer clothing.
He felt and recovered a revolver. Terry was convicted of carrying a concealed weapon after the gun was admitted into evidence.
The dispute reached the courts because the police action, prosecution, civil-rights claim, or government policy raised a constitutional question that could not be answered by the facts alone.
Issue Before the Court
Does the Fourth Amendment permit an officer, without probable cause to arrest, to briefly stop a person based on reasonable suspicion and conduct a limited frisk for weapons when the officer reasonably believes the person may be armed and dangerous?
In plain English, the court had to decide where police authority ended and constitutional protection began under the facts of this case.
Decision
Yes. The Court held that a brief investigatory stop is a seizure and a pat-down for weapons is a search, but both can be reasonable under the Fourth Amendment when supported by specific, articulable facts. An officer may conduct a limited outer-clothing frisk for weapons when reasonably warranted for officer or public safety.
The decision matters because terry created the modern stop-and-frisk doctrine: police do not always need probable cause for a brief investigative detention, but they do need reasonable suspicion based on objective facts. A frisk is not automatic; it requires a reasonable belief that the person may be armed and dangerous.
Plain-English Implications for Police Work
Police may briefly stop someone on reasonable suspicion, and may do a limited weapons pat-down only when safety concerns are objectively reasonable. Terry is a permission slip for narrow field safety measures, not a general search power.
Terry remains central to street encounters, traffic-stop extensions, suppression motions, officer-safety doctrine, and debates about over-policing. Courts still ask whether officers can point to specific facts supporting both the stop and any protective frisk.