While the constitutionality of retroactive laws has been much discussed by courts and commentators, one situation has received relatively little treatment. This is the situation arising when a law is passed which alters the effect of existing contractual obligations of the federal government. That this problem has received little treatment is quite understandable. The constitutional issue it poses is unique in that it might be viewed as anterior to that of the fairness of the retroactive law, and to concern the very different problem of the source of the government\u27s power to alter its obligation. Most commentators, have devoted their attention to the meaning of fairness in the context of retroactivity, and accordingly have not pause...