A large number of persons in the United States and Europe believe that EMF causes human illness. These illnesses include childhood leukemia, other cancers, high blood pressure, the aggravation of other diseases, and electrical sensitivity syndrome. EMF has become a legal issue as people seek compensation for alleged injuries and try to have power lines relocated away from their homes. This column discusses the problem of making good legal decisions about complex scientific problems such as EMF. Topics discussed include: the history; the Denver study; fear and the law; proving negatives and the law; economic consequences of fear; and fear and the public utility consequences. The author concludes that so far, the courts and most state public-utility regulatory commissions have acted reasonably when dealing with EMF. They have recognized that the potential risk is very small, if there is any risk at all, and that the potential harm from regulation is very high. This is a precarious balance, however, and it could easily be upset by either trial judges allowing EMF cases to be litigated or a state public-utility commission giving in to public pressure and declaring EMF a threat to health. Scientists and others who understand these problems should speak out and try to shape public opinion to diminish the suffering that comes from irrational fears and the social dislocations that follow bad policy choices.