A plaintiff in a products liability action against the manufacturer or seller of a motor vehicle is generally required to prove that the vehicle as sold contained a defect that created an unreasonable risk of death, personal injury, or property damage when the vehicle was put to its intended use and that the defect caused the loss for which the plaintiff is seeking to recover damages. The types of alleged vehicle defects that may be made the subject of an automotive products liability action include shortcomings in the design of the vehicle, mistakes made in the manufacture of its parts or in their assembly into a completed car or truck, and failure to warn the purchaser or operator of the vehicle about dangers inherent in its use and operation. Because products liability actions involve complex technical issues of science and engineering, expert witnesses are normally made use of by both sides in trying to either prove a case of liability or establish a defense.
The rules of evidence employed by the courts set out the qualifications for expert witnesses, which can in a general way be said to consist of some special degree of education, training, or experience that creates a level of knowledge in a scientific or technical area beyond that of persons who are not so educated, trained, or experienced. Unlike most witnesses, expert witnesses are allowed not merely to give testimony covering facts known to them, but are permitted, based on the factual evidence that has been brought forth in the case, to express their opinions on the technical issues involved. Such opinion testimony may be crucial in establishing the existence or non-existence of a product defect, the manner in which an alleged defect caused or did not cause the accident that resulted in the litigation, and numerous other necessary matters of proof. The courts have traditionally taken a liberal attitude toward the admission of expert testimony, but recently, following several decisions by the Supreme Court of the United States that authorized stricter scrutiny of the foundations of an expert witness’s opinions, courts have been exercising tighter control over the admission of expert testimony that lacks the underpinnings of a recognized scientific or technical method.
The law of products liability in the United States, including automotive products liability law, has evolved over the course of more than half a century out of developments in the legal systems of the individual states rather than out of a single unified system of federal law. (The National Highway Traffic Safety Administration, popularly known as NHTSA, has enacted a body of Federal Motor Vehicle Safety Standards, or FMVSS, with which every new motor vehicle sold in the United States has to comply, and these regulatory standards may play a role in automotive products liability cases.) While the principles of products liability law in the different states contain many similarities, the legal standards governing the admission and use of the testimony of expert witnesses in automotive products liability cases will vary from state to state.