In which case was the validity of a stop and frisk based on reasonable suspicion established?

The case that established the validity of a stop and frisk based on reasonable suspicion is Terry v. Ohio. This landmark Supreme Court decision set the precedent for law enforcement officers to stop a person and conduct a brief investigation if they have a reasonable suspicion that the individual is involved in criminal activity. The ruling emphasized the balance between individual rights and public safety, allowing officers to perform a limited pat-down search for weapons if they believe the person may be armed and dangerous. Terry v. Ohio clarified that reasonable suspicion is a lower standard than probable cause and is sufficient for officers to engage in these precautionary measures designed to protect both themselves and the public. This case is foundational in understanding the legal basis for stop and frisk practices in the United States.