(a) the other parties by unanimous agreement to suspend the operation of the treaty in whole or in part or to terminate it either: (i) in the relations between themselves and the defaulting State or international organization; or
(ii) as between all the parties;
(b) a party specially affected by the breach to invoke it as a ground for suspending the operation of the treaty in whole or in part in the relations between itself and the defaulting State or international organization;
(c) any party other than the defaulting State or international organization to invoke the breach as a ground for suspending the operation of the treaty in whole or in part with respect to itself if the treaty is of such a character that a material breach of its provisions by one party radically changes the position of every party with respect to the further performance of its obligations under the treaty.
3. A material breach of a treaty, for the purposes of this article, consists in:
(a) a repudiation of the treaty not sanctioned by the present Convention; or
(b) the violation of a provision essential to the accomplishment of the object or purpose of the treaty.
4. The foregoing paragraphs are without prejudice to any provision in the treaty applicable in the event of a breach.
5.Paragraphs 1 to 3 do not apply to provisions relating to the protection of the human person contained in treaties of a humanitarian character, in particular to provisions prohibiting any form of reprisals against persons protected by such treaties.
Article 61
Supervening impossibility of performance
1. A party may invoke the impossibility of performing a treaty as a ground for terminating or withdrawing from it if the impossibility results from the permanent disappearance or destruction of an object indispensable for the execution of the treaty. If the impossibility is temporary, it may be invoked only as a ground for suspending the operation of the treaty.
2. Impossibility of performance may not be invoked by a party as a ground for terminating, withdrawing from or suspending the operation of a treaty if the impossibility is the result of a breach by that party either of an obligation under the treaty or of any other international obligation owed to any other party to the treaty.
