United States v. Mohamed Belakhdhar, 924 F.3d 925

DEA arranged a confidential informant to buy heroin; supplier Henry Soto was to drive the shipment from Chicago to Detroit the next morning, and agents obtained a cell‑phone ping warrant for Soto.
Agents identified Soto’s black Camry on I‑94 and observed a grey Toyota RAV4 with temporary Illinois tags following the Camry closely and changing lanes in tandem; agents asked Michigan State Police to stop both vehicles.
State troopers stopped the Camry and the RAV4; troopers briefly detained Belakhdhar (RAV4 driver), obtained IDs, and conducted a consent search that found nothing; troopers released them.
DEA continued surveillance, discovered Belakhdhar lacked immigration status, asked Border Patrol to stop the RAV4 a second time, and during that stop a drug dog alerted; opening the trunk revealed two kilograms of heroin concealed in a microwave.
Belakhdhar moved to suppress the evidence, arguing the initial stop violated the Fourth Amendment for lack of reasonable suspicion; the district court granted suppression and the government appealed.

Issue	Belakhdhar's Argument	Government's Argument	Held
Whether driving in tandem with a vehicle suspected of carrying drugs can, by itself, give reasonable suspicion to stop the second vehicle	Tandem driving alone is insufficient; the initial stop lacked reasonable suspicion and thus tainted subsequent seizure	Tandem driving plus identification of a suspect car (Camry) and CI information provided a particularized and objective basis for suspicion	As a matter of law, tandem driving with a vehicle suspected of drug activity can support reasonable suspicion when supported by other facts; district court erred to hold it never can

Wong Sun v. United States, 371 U.S. 471 (fruit of the poisonous tree doctrine applied to suppress evidence)
Terry v. Ohio, 392 U.S. 1 (standard for investigatory stops and reasonable suspicion)
United States v. Arvizu, 534 U.S. 266 (totality‑of‑circumstances test for reasonable suspicion)
United States v. Cortez, 449 U.S. 411 (particularized and objective basis for detention)
Navarette v. California, 572 U.S. 393 (reasonable suspicion is a low threshold)
Ybarra v. Illinois, 444 U.S. 85 (mere propinquity to suspected wrongdoing insufficient for probable cause)
United States v. Carrillo–Alvardo, [citation="558 F. App'x 536"] (tandem driving plus additional corroborating facts can supply reasonable suspicion)
United States v. Smith, 263 F.3d 571 (aggregate innocent facts may support suspicion under totality of circumstances)