Federal Motor Vehicle Safety Standard 208 (1989 version) requires, among other things, that auto manufacturers install seatbelts on the rear seats of passenger vehicles. They must install lap-and-shoulder belts on seats next to a vehicle’s doors or frames. But they have a choice about what to install on rear inner seats (say, middle seats or those next to a minivan’s aisle). There they can install either (a) simple lap belts or (b) lap-and-shoulder belts. In 2002, the Williamson family, riding in their 1993 Mazda minivan, was struck head on by another vehicle. Thanh Williamson was sitting in a rear aisle seat, wearing a lap belt; she died in the accident. Delbert and Alexa Williamson were wearing lap-and-shoulder belts; they survived. They subsequently brought a California tort suit against Mazda, claiming that Mazda should have installed lap-and-shoulder belts on rear aisle seats, and that Thanh died because Mazda equipped her seat with a lap belt instead. As contrasted with Geier, in which the regulation’s history, the agency’s contemporaneous explanation, and its consistently held interpretive views, all indicated that the regulation sought to maintain manufacturer choice in order to further significant regulatory objectives; the Court found that in the case of rear-seat lap-and-shoulder belts, these same considerations indicate the contrary. “We consequently conclude that, even though the state tort suit may restrict the manufacturer’s choice, it does not ‘stand as an obstacle to the accomplishment … of the full purposes and objectives’ of federal law.” See Williamson v. Mazda, 131 S.Ct. 1131 (2011).