The doctrine of changed circumstances has made its impact into all major legal systems as well as public international law. Although the doctrine has its roots in the civilian law tradition, it has been received by the Anglo-American common law and the modern Islamic legal system as well. The doctrine has been invoked in several important international litigations in recent times, including the Iran-United States disputes. The application of the doctrine of changed circumstances will be studied here separately under (1) international law, (2) Anglo-American law and (3) contemporary Islamic laws.

The existence in international law of the doctrine of rebus sic stantibus has been accepted by the majority of modern writers.1 This concept, somewhat analogous to changed circumstances, has a very limited application to the international law in general. Accordingly, international treaties are subject to an implied condition that if there occurs a material change in the state of things which was foundation of the agreement, and if by an unforeseen change in circumstances an obligation provided for in the treaty should imperil the existence or vital development of one of the parties, the party State should be entitled to claim to be released from the obligation concerned. The doctrine does not provide that a State is automatically released from its treaty obligation, but only that it may request the other parties to agree to abrogation of the treaty.

The rule of the fundamental change of circumstances has been defined by the International Law Commission as follows:

“When a fundamental change has occurred with regard to a fact or situation existing at the time when the treaty was entered into, it may be invoked on a ground for terminating or withdrawing from treaty if (a) the existence of that fact or situation constituted an essential basis of the consent of the parties to the treaty; and (b) the effect of the change is to transform in an essential respect the character of the obligations undertaken in the treaty”.

If the doctrine of rebus sic stantibus applies to international contracts at all, its application would be very limited indeed. Recent research has disclosed no evidence