Court: Drug-sniffing dog searches of cars limited

WASHINGTON — The Supreme Court told the police Tuesday they may not turn routine traffic stops into drug searches using trained dogs.

The 6-3 decision limits the practice whereby officers stop a car for a traffic violation and then call for a drug-sniffing dog to inspect the vehicle.

The justices, both liberal and conservative, agreed that it was an unconstitutional “search and seizure” to hold a motorist in such cases.

“Police may not prolong detention of a car and driver beyond the time reasonably required to address the traffic violation,” said Justice Ruth Bader Ginsburg.

The decision applies the Fourth Amendment’s ban on “unreasonable searches and seizures” and covers all police. Ginsburg said police officers who stop a car for speeding or another traffic violation are justified in checking the motorist and his driver’s license. But a traffic stop does not give officers the authority to conduct an “unrelated” investigation involving drugs, she said.

“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 and attend to related safety concerns,” she explained in Rodriguez v. United States. “Authority for the seizure thus ends when tasks tied to the traffic infraction are — and reasonably should have been — completed.”

Chief Justice John Roberts and Justices Antonin Scalia, Stephen Breyer, Sonia Sotomayor and Elena Kagan joined her opinion.