Justices Hear Case on Drug-Detection Dogs

"Does it matter that in today's world on Capitol Hill we're concerned with terrorist attacks?" O'Connor asked. "Can they search [with dogs] for explosives in parked cars?"

Meczyk said such a search would be justified by "public safety," but the search of Caballes's car "invaded a private space that in this case . . . Caballes had a privacy interest in."

Justice Stephen G. Breyer pressed Meczyk to explain whether "there would be anything wrong with the officer himself taking a sniff," if, for example, the authorities were trying to investigate a hypothetical "great Limburger cheese robbery."

"I'm not saying you couldn't draw the line," Breyer added. "But it is a pretty tough one."

Still, the state encountered skepticism from some members of the court. Those justices seemed concerned that if the court approved the more or less random use of sniffer dogs, as in the Caballes case, that there might be no way to limit their use.

Justice David H. Souter raised the specter of police with dogs "going through every municipal garage or going up to every home and ringing the bell."

"We're opening up rather a large vista for dog intrusion," he said.

Justice Ruth Bader Ginsburg commented that "dogs can be frightening and humiliating."

"There is some association between the idea that I have a right to be let alone by the government and not having a large dog circle my car," she said.

Madigan replied that any such risk was mitigated by the fact that the public encounters dogs regularly.

For the sixth straight oral argument session, Chief Justice William H. Rehnquist did not appear yesterday, but Justice John Paul Stevens announced that Rehnquist will vote on the case.

The case is Illinois v. Caballes, No. 03-923. A decision is expected by July.