Mazda, which made the minivan, had argued that the lawsuit should be dismissed because the company had complied with federal safety regulations, which allowed it choose to install simple lap belts or lap-and-shoulder belts in some rear seats.
The company relied on a 2000 Supreme Court decision in a case involving a similar regulation that gave automakers the option of installing air bags. In that case, the court ruled that the regulation foreclosed the filing of injury suits under state law by people contending that manufacturers had made the wrong choice.
Justice Stephen G. Breyer wrote the majority opinion in the 2000 decision, Geier v. American Honda Motor Company, and he was the author of the court’s opinion on Wednesday. He acknowledged that the two cases were in some ways quite similar, but he said that the differing goals of federal safety regulators required different results.
Justice Clarence Thomas, who agreed with the result reached by the majority on Wednesday but disagreed with its reasoning, mocked the distinctions cited by Justice Breyer.
“The dispositive difference between this case and Geier — indeed, the only difference — is the majority’s ‘psychoanalysis’ of the regulators,” Justice Thomas wrote.
The new case arose from the death in 2002 of Thanh Williamson, who was riding in a rear seat of a 1993 Mazda minivan and wearing a lap belt, the only restraint available, when it was struck head on by another vehicle. Passengers wearing lap-and-shoulder belts in the minivan survived; Ms. Williamson died.
Courts in California dismissed a suit brought by Ms. Williamson’s family contending that Mazda should have installed the more elaborate restraints throughout the minivan, relying on the Geier decision. That decision said that injury suits brought under state law challenging the failure to install air bags stood as an obstacle to the objectives of federal safety regulations, which were said to be the maintenance of manufacturers’ choices.
Geier was decided by a 5-to-4 vote. In dissent, Justice John Paul Stevens said the majority had made “unprecedented use of inferences from regulatory history and commentary” to bar the lawsuit there.
Justice Breyer’s opinion on Wednesday in Williamson v. Mazda Motor of America, No. 08-1314, did not disavow Geier. “We concede,” he wrote, “that the history of the regulation before us resembles the history of air bags to some degree.”
But Justice Breyer said there were important differences, too. Among them, he wrote, was that regulators “were not concerned with consumer acceptance” of lap-and-shoulder restraints; were convinced that the restraints would increase safety; “did not fear additional safety risks arising from use of those belts”; “had no interest in assuring a mix of devices”; and had a diminishing concern about the cost of installing the more elaborate restraints.
Justice Breyer added that the federal government had urged the Supreme Court to bar the lawsuit in Geier but to allow the suit by Ms. Williamson’s family.
Justice Elena Kagan did not participate in Wednesday’s decision because she had worked on the case as United States solicitor general.
In his concurrence, Justice Thomas said the text of the relevant federal law specifically allowed suits like the ones here and in Geier.
He added that he found the majority’s methodology in distinguishing the two cases unconvincing.
“The court wades into a sea of agency musings and government litigating positions,” Justice Thomas wrote, “and fishes for what the agency may have been thinking 20 years ago when it drafted the relevant provision.”