There are number of ways by which treaties may be terminated or suspended. The methods of termination or suspension of a treaty and its effects are enumerated in Articles 45, 54, 56, 57, 59-62, 70 and 72.
Termination by consent and by treaty provision
Articles 54 and 57 stipulate that a treaty may be terminated or suspended in conformity with the provisions of that treaty or at any time by consent of all the parties after consultation with the other contracting states. Where, however, a treaty does not contain any provision regarding termination or expressly provide for denunciation or withdrawal, Article 56 provides that a state may only denounce or withdraw from that treaty where the parties intended to admit such a possibility or where such right is implicit by the nature of the treaty.
A treaty may terminate if its purposes and objects have been fulfilled or if it is limited in time and that time has elapsed.
Article 58 of the Convention stipulates that two or more parties to a multilateral treaty may conclude an agreement to suspend the operation of provisions of the treaty, temporarily and as between themselves alone, if:
(a) the possibility of such a suspension is provided for by the treaty; or
(b) the suspension in question is not prohibited by the treaty and:
(i) does not affect the enjoyment by the other parties of their rights under the treaty or the performance of their obligations;
(ii) is not incompatible with the object and purpose of the treaty.
Article 59 of the Convention provides that where the parties to a treaty conclude another treaty relating to the same subject matter, then the earlier treaty will be deemed to have been terminated where it appears that the matter is to be governed by the later agreement or where the provisions of the later treaty are so incompatible with those of the earlier treaty that the two treaties are not capable of being applied at the same time.
Termination or suspension as a consequence of breach
An obvious corollary to the breach of a treaty is that the party adversely affected by the breach is entitled to terminate the treaty. However, this right as in the case of a breach of contract may be waived by the party affected. Where a breach occurs in a bilateral treaty, the aggrieved state may consider the breach as a ground for terminating the treaty or suspending its operation wholly or in part. Where a material breach occurs in a multilateral treaty the breach entitles the other parties by unanimous agreement to suspend the operation of the treaty in whole or in part or to terminate it either in the relations between themselves and the defaulting state or as between all the parties. Secondly, where a party is specially affected by the breach, it is entitled 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. Article 60 (3) states that a material breach of a treaty consists in either a repudiation of the treaty not sanctioned by the Convention or the violation of a provision essential to the accomplishment of the object or purpose of the treaty. The latter portion of sub-clause 3 was applied in the Rainbow Warrior Case where pursuant to an agreement between New Zealand and France (concluded in the form of exchange of letters) of 9 July 1986, France was under an obligation to keep two of its agents, guilty of bombing the Greenpeace ship the Rainbow Warrior in July 1985, on the French military facility island of Hao for a minimum period of three years was held to have constituted the object or purpose of the above agreement. France permitted the agents to leave the island (for medical reasons) before the expiry of the three-year period.
Supervening impossibility of performance
Where the performance of a treaty is rendered impossible due to the permanent disappearance or destruction of an object indispensable for the execution of the treaty, a party may invoke the provisions of Article 61 and validly terminate or withdraw from it. If however, the impossibility is temporary, it may be invoked for suspending the operation of the treaty. If impossibility is as a result of a breach by a party either of an obligation under the treaty or of any other international obligation owed to any other party to the treaty, then impossibility may not be invoked by that party as a ground for terminating, withdrawing from or suspending the operation of the treaty.
Rebus sic stantibus or fundamental change of circumstances
The doctrine rebus sic stantibus is a principle of customary international law that provides that where a fundamental change of circumstance has taken place since an agreement was concluded, a party to that agreement may withdraw from or terminate it. It is essentially an "escape clause" that makes an exception to the general rule of pacta sunt servanda – promises must be kept. Article 62 of the Convention incorporates this principle although this doctrine is never mentioned by name. Article 62 provides the only two justifications of the invocation of rebus sic stantibus: first, that the circumstances existing at the time of the conclusion of the treaty were indeed objectively essential to the obligations of treaty (sub-paragraph A) and the instance wherein the change of circumstances has had a radical effect on the obligations of the treaty (sub-paragraph B).
If the parties to a treaty had contemplated for the occurrence of the changed circumstance the doctrine does not apply and the provision remains in effect. Clausula rebus sic stantibus only relates to changed circumstances that were never contemplated by the parties. This principle is clarified in the Fisheries Jurisdiction Case (United Kingdom v. Iceland, 1973). In that case, in 1972, Iceland attempted to extend its exclusive fisheries zone from 12 miles to 50 miles. United Kingdom objected to the extension of the zone by Iceland and the dispute resulted in what came to be known as the “Cod War” The International Court of Justice in that case observed:
It is, notes the Court, admitted in international law that if a fundamental change of the circumstances which induced parties to accept a treaty radically transforms the extent of the obligations undertaken, this may, under certain conditions, afford the party affected a ground for invoking the termination or suspension of the treaty.
In this case the Court considered whether the agreement of 1961 between Iceland and the United Kingdom, certain provisions of which were in issue in the proceedings before the Court, had come to an end due to fundamental change of circumstances affecting fisheries and fishing techniques and legal opinion on the extent of the jurisdiction. Insofar as the fundamental change of circumstances affecting fisheries and fishing techniques were concerned, the Court did not find it necessary to decide whether the changes were fundamental, and held that in any case the alleged changes could not affect the only provision in the agreement with which the Court was concerned, providing for submission of disputes to the Court. The change of circumstances to give rise to a ground for invoking termination of a treaty, it was also necessary that it should have resulted in a radical transformation of the extent of the obligations still to have been performed. The change must have increased the burden of the obligations to be executed to the extent of rendering the performance something essentially different from the one originally undertaken. The Court did not consider that condition to have been satisfied. As to the change in the legal opinion on the extent of the fisheries jurisdiction, the Court observed that ‘changes in the law may under certain circumstances constitute valid grounds for invoking a change of circumstances affecting the duration of a treaty’. Nevertheless, the Court held that the fact Iceland may have entered into the agreement in order to obtain immediate recognition of a 12-mile exclusive fisheries zone, and that such a 12-mile zone may no longer be in dispute between the parties, did not mean that the agreement could be regarded as terminated. The object of the agreement was wider than mere recognition of the 12-mile zone and although some of the motives which may have persuaded Iceland to enter into the agreement might not be in existence, it did not justify the repudiation of those parts of the agreement, the object and purpose of which had remained unchanged. The Court also noted that the agreement was in part executed and in part executor, one of the parties having obtained benefit from the executed provisions of the treaty. Hence it was inadmissible to allow that party to put an end to obligations which were accepted under the treaty by way of a quid pro quo for the provisions which the other party had already executed.
Consequences of termination or suspension of a treaty
Article 70 provides for consequences of termination of a treaty:
1. Unless the treaty otherwise provides or the parties otherwise agree, the termination of a treaty under its provisions or in accordance with the present Convention:
(a) releases the parties from any obligation further to perform the treaty;
(b) does not affect any right, obligation or legal situation of the parties created through the execution of the treaty prior to its termination.
2. If a State denounces or withdraws from a multilateral treaty, paragraph 1 applies in the relations between that State and each of the other parties to the treaty from the date when such denunciation or withdrawal takes effect.
Termination of a treaty, thus, unless otherwise provided, releases the parties from any performing any future obligations, but does not affect any right, obligation or legal situation created through execution of the treaty prior to its termination. If a treaty is declared void because it conflicts with a peremptory norm there is a duty cast on the parties to eliminate as far as possible the consequences of any act performed in reliance on such offending provision and with bringing their mutual relations into conformity with the peremptory norm of general international law.
Article 71(2) provides that if a treaty becomes void and terminates under article 64, the termination of the treaty, the parties are released from any further obligation to perform the treaty, but the rights, obligations and legal situation of the parties created prior to the termination are not affected, provided that those rights, obligations or situations may thereafter be maintained only to the extent that their maintenance is not in itself in conflict with the new peremptory norm of general international law.