David and Elizabeth Trull (Ps), and their two sons, Nathaniel and Benjamin, were traveling when their Volkswagen Vanagon slid on black ice and collided with an oncoming car. Nathaniel and Benjamin were seated in the rear middle bench seat of the Vanagon, which was equipped with lap-only seatbelts, and were wearing the available lap belts. Benjamin died in the accident, and both Elizabeth and Nathaniel suffered severe brain injuries. Ps sought damages 'on the ground that defects in the design of the Vanagon made their injuries more severe than they otherwise would have been.' Ps claimed (1) the Vanagon was defective because it was a forward control vehicle constructed in such a way that it lacked sufficient protection against a frontal impact, and (2) the Vanagon was defective because the rear bench seats did not have shoulder safety belts as well as lap belts. Volkswagen got the jury verdict. Ps appealed. The court of appeals certified a question to the New Hampshire Supreme Court to determine which party under state law bears the burden of segregating the injuries caused by a vehicle’s design defect in a “crashworthiness” case.