Product Liability, Design Defects and Manufacturing Defects are obvious arenas for an experienced manufacturing engineer or process engineer. He has the insight to best evaluate manufacturing defects in product liability cases. Naturally, he must first perform a complete root cause failure analysis to determine if there was product misuse, a manufacturing defect or a design defect. Naturally it is a benifit if the chosen engineer has experience with similar products, materials and processes in question. This is an asset because he can relate the defect back to a specific process step. In addition, he will be familiar with what is necessary for correct product development. An example is a case where a product failed after a short time in service. He is best qualified to determine if the product or process development procedures were thorough and proper. For example, he can determine if the proper accelerated life tests were performed to determine the product performance over its expected lifetime. Product development and process development usually occur in four stages: concept, bread board, pilot production and full production. An important aspect of this cycle is to determine if there are potential circumstances during normal use that might cause product failure and/or personnel injury. Documented tests must be performed to prove that the hypothetical degradation mechanisms do not cause premature product failure. If this is not done, an unreliable or dangerous product (i.e. poor product safety) may be put on the market. An experienced manufacturing engineer is the best prepared to determine if the product was properly developed to allow for proper product quality. This insight can only be gained from direct hands on manufacturing experience.