Clausula Rebus Sic Stantibus

a direct or implied condition in a treaty that the treaty will remain in force for as long as the circumstances under which it was made remain unchanged.

Clausula rebus sic stantibus substantiates the legality of a refusal to continue to observe a treaty or its individual provisions. It became established as a principle of bourgeois law in the 19th century as a counterbalance to the earlier principle of the “unchangeability of treaties.” To preserve the stability of international obligations, the reservation can be applied only in instances of unquestionable and exceptionally serious grounds. The 1969 Vienna convention on the law of international treaties stipulates that a fundamental change of circumstances may serve as grounds for withdrawal from the treaty only if changes occurred that could not have been foreseen by the parties when the treaty was signed, if these changes represented an important factor in the agreement, and if the changes materially affected the obligations undertaken by the parties to the treaty.