Unexpected change of circumstances: perspectives of legal history

From the historical perspective, basically three legal concepts are worth exploring with regard to the influence of an unexpected change of circumstances on legal transactions. The first one, the clausula rebus sic stantibus doctrine, has its roots in Roman philosophy and was developed as a normative rule during the Middle Ages. Second, the concept of (tacit) presupposition (‘Voraussetzungslehre’) emerged in the German legal discourse of the late nineteenth century. At the same time the third doctrine to be examined here, the idea of frustration of contract, was created by the English courts in order to cope not only with an unexpected change of circumstances in general, but also with cases of impossibility. In Section 2 below the Roman foundations of the clausula rule and the emergence of this doctrine during the period of the ius commune, which began in the thirteenth century will be discussed. Section 3 addresses the development of that doctrine in the Early Modern Period between the sixteenth and the eighteenth centuries. The final section will focus on the development during the nineteenth and the early twentieth centuries in which the doctrine of presupposition and the idea of frustration have come to the fore (section below).