A fatigue failure, its causes and its remedies may be identified, but their relative importance is usually assessed by the use of extrinsic value systems. The failure may be evaluated by comparing it to the anticipated, expected, specified or needed performance. This may be done by peer specialists, other company engineers, by the customer or by the ultimate user of a product. Their value systems help determine whether a failure is tolerable or unacceptable. In addition, societal value systems may be incorporated into legal rules, government regulations and product liability laws that may be used to evaluate a particular failure. These societal value systems may have severe penalties attached to violations and may be applied in unfamiliar foreign countries. Thus, to properly `evaluate' failures, the engineering specialist must now `understand' potential product liability implications, on a worldwide basis, and his own technical value system may be transformed in the learning process. Some of the more important basic legal concepts that should be clearly understood are foreseeability, reasonableness and due care. In terms of risk, there are legal aspects, derivative engineering aspects and supplemental risk concepts. Central to this understanding are various risk concepts relating to techniques for the estimation of a failure's capacity to do harm, the type of risk data utilized for a particular analytic purpose, the method selected for risk assessment and risk categorization, and variations legally required in risk analysis by engineers and scientists. The concepts relating to risk have been defined and elaborated to such an extent that they are a fundamental means of communicating the relative meaning of a failure in the context of the real world marketplace. The legal aspects of failure analysis are extremely important in formulating design engineering criteria as well as marketing strategies. Such concepts should be considered in the perspective of current perturbations and transitional forces effecting the cost of noncompliance. Liability prevention is increasingly a professional obligation and a personal responsibility of engineering specialists.