It's amusing to see what sort of torture the USSC goes through in an attempt to "find consensus."
1. Absent reasonable suspicion, police extension of a traffic stop in order to conduct a dog sniff violates the Constitution’s shield against unreasonable seizures. A routine traffic stop is more like a brief stop under Terry v. Ohio, 392 U. S. 1, than an arrest, see, e.g., Arizona v. Johnson, 555 U. S. 323, 330. Its tolerable duration is determined by the seizure’s “mission,” which is to address the traffic violation that warranted the stop, Illinois v. Caballes, 543 U. S. 405, 407 and attend to related safety concerns. Authority for the seizure ends when tasks tied to the traffic infraction are—or reasonably should have been— completed. The Fourth Amendment may tolerate certain unrelated investigations that do not lengthen the roadside detention, Johnson, 555 U. S., at 327–328 (questioning); Caballes, 543 U. S., at 406, 408 (dog sniff), but a traffic stop “become[s] unlawful if it is prolonged beyond the time reasonably required to complete th[e] mission” of issuing a warning ticket, id., at 407.
Beyond determining whether to issue a traffic ticket, an officer’s mission during a traffic stop typically includes checking the driver’s license, determining whether there are outstanding warrants against the driver, and inspecting the automobile’s registration and proof of insurance. These checks serve the same objective as enforcement of the traffic code: ensuring that vehicles on the road are operated safely and responsibly. See Delaware v. Prouse, 440 U. S. 648, 658–659. Lacking the same close connection to roadway safety as the ordinary inquiries, a dog sniff is not fairly characterized as part of the officer’s traffic mission.
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