In the US, the substantive rules of product liability are primarily determined by state courts and legislatures. Because the US has a common law system, state courts have played an especially important role in the area of product liability and tort more generally. While strict product liability was developed exclusively by state courts, once it became established, some state legislatures enacted statutes to govern product liability cases. The more comprehensive ones tended to adopt the law that had developed through the common law and place it into statutory form. In some cases, those statutes modified one or more aspects of product liability law that the courts had developed. In addition, the US has had several rounds of ‘tort reform’, in which state legislatures have restricted tort law, and some of those reforms were targeted specifically at product liability claims or, because of their breadth, encompassed product claims as well as other tort claims.
It is true that federal law sets some important limits on state product liability law in certain areas subject to federal regulation. For example, because, under the US Constitution, federal law pre-empts conflicting state law, manufacturers of generic drugs, medical devices, and automobiles who have satisfied federal-law regulations with respect to safe product design, or warnings of product risks, are sometimes immune from liability under state tort law. In addition, the US Supreme Court has identified federal constitutional limits on when, how, and in what amounts punitive damages may be awarded. Still, state law is the primary source of law governing liability for product-related injuries.
It would be a significant overstatement to say that, in substance, the US has 51 different versions of product liability law: there is a good deal of uniformity across the product liability law of each state and the District of Columbia. But there are also important differences, and thus it is oft en inaccurate to speak and write as if there were a single US product liability law. In what follows, we will aim to address the product liability issues confronted in this volume by reference to legal rules that have gained broad acceptance across the different US jurisdictions, and we will also try to note areas in which the law varies significantly among jurisdictions.