10.4 Fundamental change of circumstances : A fundamental change of the circumstances existing at the time the treaty was concluded has traditionally been a ground for withdrawal or termination. The rule is often referred to as the doctrine of rebus sic stantibus. Before the First World War a number of treaties were brought to an end by states relying on fairly minor changes. Since that time the law has been tightened up and it is

doi:10.4324/9781843143802-38

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10.4 Fundamental change of circumstances

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ABSTRACT

general defence to international responsibility. The requirements of force majeure are that it must be irresistible, unforeseeable and external to the party relying on it. It may therefore exist under conditions which fall short of absolute material impossibility of performance. At the Vienna Conference on the Law of Treaties Mexico proposed that force majeure should be included in Article 61 but the proposal was rejected. It therefore seems to be the case that although force majeure may provide a defence for states accused of breaching treaty obligations, it will not result in the termination of the treaty. However, since a material breach of a treaty can result in the termination of that treaty, it may be argued that the ultimate effect of force majeure will be the same as a material impossibility of performance.