City of Indianapolis v. Edmond
City of Indianapolis v. Edmond, 531 U.S. 32 (2000), was a United States Supreme Court case in which the Court held, 6–3, that police may not conduct vehicle searches, specifically ones involving drug-sniffing police dogs, at a checkpoint or roadblock without reasonable suspicion.
Source: Wikipedia — City of Indianapolis v. Edmond (CC BY-SA 4.0)