WASHINGTON – Most of the Supreme Court justices said Wednesday they see no reason to limit a police officer’s use of a dog to sniff out drugs or explosives.

The Supreme Court is being urged to overturn a decision of the Illinois Supreme Court last year that held that a police officer who stops a car for speeding must have evidence of a drug crime before he calls in a drug-sniffing dog. Otherwise, the state judges said, all traffic stops could turn into drug searches.

But some Supreme Court justices seemed to view the issue differently during oral arguments Wednesday.

“A dog sniff is not a search,” Justice Sandra Day O’Connor told a lawyer for the Illinois defendant, flatly rejecting the essence of his case.

Around Capitol Hill, O’Connor said, there are many security checkpoints, and some use dogs to check cars, packages and backpacks. Are all those searches unconstitutional? she asked.

In their comments and questions, O’Connor and most of her colleagues said they were not prepared to rule that a police officer must first have hints of a crime before he uses a dog to sniff for evidence.

“Dogs are used all over the country with great effectiveness,” Christopher Wray, an assistant attorney general, told the court. They sniff for bombs and drugs at the borders, at airports and bus stations, and around cars that are stopped on the highway. “There is no intrusion (on the privacy of the owner), and therefore no search,” he said.

Illinois Attorney General Lisa Madigan argued that nothing in the Constitution prevents the police from using dogs to sniff around cars. “A dog sniff is not a search and requires no justification,” she said.

Madigan and the Bush administration are urging the justices to overturn the Illinois Supreme Court decision.

That ruling had been a victory for Ray Caballes, a salesman who said he was moving from Las Vegas to Chicago in November 1998. An Illinois state trooper stopped him on Interstate 80 for driving 71 mph in an area where the speed limit was 65.When the state trooper stopped Caballes, another trooper radioed that he would be there shortly with a drug-sniffing dog. Immediately, the dog responded to smells from the trunk of the car, and there the troopers found a large quantity of marijuana.

The Fourth Amendment bans “unreasonable searches and seizures” by the government, and the justices have struggled for decades to decide what is and is not an “unreasonable search.”

Only two justices, David Souter and Ruth Bader Ginsburg, raised doubts about the widespread use of dogs.

If the use of a sniffing dog is not a search, “why can’t police go up to the front door of every house on the street?” asked Souter. When the homeowner came to the door, the dog could sniff for drugs inside, he said.

The government lawyers said police were unlikely to undertake such efforts.

Associated Press

Illinois Attorney General Lisa Madigan responds to questions Wednesday after arguing the case for drug-sniffing dogs before the Supreme Court.