Abstract
The legal and economic consequences of nonuse of self-protective devices are discussed. The analysis develops a theoretical framework for considering such devices, examines in the context of that framework the use of one device (an available automotive seat belt), and proposes a change in the liability rule for seat-belt nonuse. Accident and prevention costs provide the best available indication of the direction in which the law should proceed on self-protective precautions. Failure to avoid needless injuries is as wasteful as failure to avoid needless accidents.