Supreme Court says Traffic Stop Cannot be Prolonged for Dog Sniff

A seizure for a traffic violation justifies a police investigation of that violation. “[A] relatively brief encounter,” a routine traffic stop is “more analogous to a so-called ‘Terry stop’ . . . than to a formal arrest.” Knowles v. Iowa, 525 U. S. 113, 117 (1998) (quoting Berkemer v. McCarty, 468 U. S. 420, 439 (1984), in turn citing Terry v. Ohio, 392 U. S. 1 (1968)). See also Arizona v. Johnson, 555 U. S. 323, 330 (2009). Like a Terry stop, the tolerable duration of police inquiries in the traffic-stop context is determined by the seizure’s “mission”—to address the traffic violation that warranted the stop, Caballes, 543 U. S., at 407, and attend to related safety concerns, infra, at 6–7. See also United States v. Sharpe, 470 U. S. 675, 685 (1985); Florida

v. Royer, 460 U. S. 491, 500 (1983) (plurality opinion) (“The scope of the detention must be carefully tailored to its underlying justification.”). Because addressing the infraction is the purpose of the stop, it may “last no longer than is necessary to effectuate th[at] purpose.” Ibid. See also Caballes, 543 U. S., at 407. Authority for the seizure thus ends when tasks tied to the traffic infraction are—or reasonably should have been—completed. See Sharpe, 470 U. S., at 686 (in determining the reasonable duration of a stop, “it [is] appropriate to examine whether the police diligently pursued [the] investigation”).

Although the Supreme Court held that a police officer can conduct a dog sniff on your car during a traffic stop, the Court now holds that the stop cannot be prolonged for the same dog sniff?

Compares a Dog Sniff Case

A dog sniff, by contrast, is a measure aimed at “detect[ing] evidence of ordinary criminal wrongdoing.” Indianapolis v. Edmond, 531 U. S. 32, 40–41 (2000). See also Florida v. Jardines, 569 U. S. 1, ___–___ (2013) (slip op., at 7–8). [If an officer can complete traffic-basedinquiries expeditiously, then that is the amount of “time reasonably required to complete [the stop’s] mission.” Caballes, 543 U. S., at 407. As we said in Caballes and reiterate today, a traffic stop “prolonged beyond” thatpoint is “unlawful.” Ibid. The critical question, then, is not whether the dog sniff occurs before or after the officer issues a ticket, as JUSTICE ALITO supposes, post, at 2–4, but whether conducting the sniff “prolongs”—i.e., adds time to—“the stop,” supra, at 6.]

Once the traffic stop is over and the driver is free to leave, the prolonging of the stop without probable cause for a dog sniff is considered a fourth amendment violation.