When an accident involving a product occurs, the injured party often files a lawsuit claiming that there was a defect in the manufacture or design of the product. How are these product liability claims proven? While the elements of a design or manufacturing defect claim vary from state to state, the role of the expert is often pivotal. In fact, in certain circumstances, the plaintiff cannot present his case to the jury unless he has obtained and can offer the requisite expert testimony. Contesting the manufacturer’s design often raises issues concerning the state of the art of the applicable technology when the product was manufactured, and technical and feasible alternative designs that could have been used for that product – topics on which only the expert is qualified to opine. In presenting or defending a manufacturing defect claim, the expert will analyze the manufacturer’s design specifications, formula or performance standards and opine on how the product did (or did not) materially deviate from those standards. Industry standards, like ASTM and ANSI, can play an important role in determining the existence of such defects. This presentation will discuss the elements of design and manufacturing defect claims under Ohio law, the role of the expert in establishing or defending such claims, and the relevancy and use of industry standards in the adjudication of these claims.