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II Treaty Interpretation and Other Treaty Points, Division B: Other Treaty Points, Ch.V: Termination of Treaties

From: The Law and Procedure of the International Court of Justice: Fifty Years of Jurisprudence Volume II

Hugh Thirlway

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2023. All Rights Reserved. Subscriber: null; date: 24 March 2023

International courts and tribunals, decisions — Treaties, invalidity, termination, suspension, withdrawal — Universal international organizations

(p. 1346) Chapter V:  Termination of Treaties

1.  Termination of Treaties Containing No Provision for Denunciation

In the case of the Gabčíkovo-Nagymaros Project, Hungary had claimed that a bilateral treaty with Czechoslovakia had been unilaterally terminated by Hungary in 1992, but Czechoslovakia (and subsequently Slovakia as successor State) claimed that the purported termination was invalid.256 The Court began its analysis of the matter with a statement of principle:

The 1977 Treaty does not contain any provision regarding its termination. Nor is there any indication that the parties intended to admit the possibility of denunciation or withdrawal. On the contrary, the Treaty establishes a long-standing and durable régime of joint investment and joint operation. Consequently, the parties not having agreed otherwise, the Treaty could be terminated only on the limited grounds enumerated in the Vienna Convention.257

Although the Vienna Convention was not applicable as such to the 1977 Treaty, the Court had already observed earlier in its judgment that the rules of the Convention ‘which are declaratory of customary law’ were nevertheless applicable, and decided that ‘this is the case, in many respects, with Articles 60 to 62 of the Vienna Convention relating to termination or suspension of the operation of a treaty’.258 It did not however make any finding as to the possible customary-law status of Article 65 of the Vienna Convention, laying down (inter alia) a minimum period of notice (three months) for the termination of a treaty; and this provision is of a procedural nature and thus not appropriate to be regarded as declaratory of existing law.259

The action complained of by Hungary as a ground for termination of the 1977 Treaty was the construction and putting into operation by Czechoslovakia of an alternative means of carrying out the part of the planned project that was to its benefit, in a form which became known as ‘Variant C’. The Court held that by putting Variant C into operation, which involved diverting the shared waters of the Danube, Czechoslovakia did indeed commit a breach of the Treaty. The Court then rejected Hungary’s claim (p. 1347) to be entitled to terminate it, on a procedural ground—that at the date at which gave notice terminating the Treaty, all that Czechoslovakia had done was carry out works preliminary to a breach of the Treaty.260 However, the Court also took account of the fact that, as it found, Czechoslovakia committed its unlawful act ‘as a result of Hungary’s own prior wrongful conduct’,261 in suspending operations under the Treaty; it remains slightly uncertain therefore which of these two grounds was determinative. The Court also made a rather mysterious allusion to good faith, in connection with the fact that the purported termination was effected with only six days’ notice. While citing the advisory opinion on the Interpretation of the Agreement of 25 March 1951 between the WHO and Egypt, which mentioned that the question of the period of notice of termination to be given in the absence of any provision in the treaty was to be determined by the parties ‘by consultation and negotiation in good faith’,262 the Court refrained from stating expressly either that six days’ notice was insufficient, or that the absence of consultation before the notice was given was a fatal flaw.263 Judge Herczegh recalled in his dissenting opinion that Article 65 of the Vienna Convention on the Law of Treaties qualified the provision there made for three months’ notice with the words ‘except in cases of special urgency’, and suggested that this was such a case.264 It may also be recalled that the WHO Agreement case concerned a situation in which no termination had yet been effected, and the intended termination was not on the basis of any breach or alleged breach of the agreement. The considerations regarded by the Court as appropriate in those circumstances might not necessarily be so where a State considered that its legal interests were seriously threatened as a result of a breach of a treaty by the other party, and that prompt action to terminate the treaty was required to limit the damage.265

Judge Herczegh also pointed out that Czechoslovakia was planning to carry out Variant C as an ‘approximate application’ of the Treaty. The lawfulness of its action on its own territory could not be challenged; but it could only lawfully carry out works on or affecting Hungarian territory by virtue of powers derived from the Treaty. By terminating the Treaty Hungary could therefore rob the Variant C works of any colour of legality, and, he suggested, was thus ‘the only means available to prevent Czechoslovakia diverting the Danube’ in the Hungarian sector.266 It might be objected that this argument assumes its conclusion: that it amounts to saying that Hungary’s termination was valid because Variant C was a breach of the Treaty, but at the same time that it would only be a breach because the Treaty had been terminated. That however would be an over-simplification. The Court’s argument was that the termination would only be lawful, and therefore effective in blocking Czechoslovakia’s action, if a breach of the Treaty had already been committed; but on the other hand it did in fact find that the implementation of Variant C was a breach of the Treaty (and probably a ‘material breach’—see (p. 1348) below). This result does not seem very satisfactory, and there may be room for a doctrine of ‘anticipatory breach’ as a ground for termination. As has been noted above,267 it is recognized that there are cases in which the lack of conformity of municipal legislation with the international law obligations of the State may constitute an internationally wrongful act. If there had existed Czechoslovak legislation as a basis for the Project works, including Variant C,268 then on the hypothesis (subsequently confirmed) that Variant C was not authorized by the Treaty, that legislation would have provided for the commission of an internationally wrongful act. The situation called for a balancing of two principles, here conflicting: a State’s right and duty to protect its territory and the interests of its inhabitants against wrongful prejudice caused by another State; and the interest of the international community, and of individual States, in the maintenance of the pacta sunt servanda principle and the sanctity of treaty obligations.

In the case of the Armed Activities on the Territory of the Congo (DRC v. Uganda), one of the arguments advanced by Uganda in response to the claims of the DRC concerning wrongful acts committed on the latter’s territory was that, during a defined period, Ugandan troops were present in the territory with the consent of the Government of the DRC. This was advanced as a ‘circumstance excluding responsibility’ in the terminology of the ILC Articles on State Responsibility, and handled by the Court as such. However, a key question was whether, and if so with effect from what date, the DRC had withdrawn its consent, and this can therefore be seen, in addition or alternatively, as an issue of the termination of an informally-created treaty-relationship.

The parties were agreed that initially, from a date around May 1997 until around August 1998, the troops had been present in Congolese territory with the consent of the Congolese Government, but the precise terms of the consent, which might perhaps have been characterized rather as an absence of objection, were obscure.269 On 27 April 1998, the two States signed a Protocol on Security along the Common Border, providing that their respective armies would ‘co-operate to insure security and peace along the common border’.270 The Court found that ‘[t]he source of an authorization or consent to the crossing of the border by [the Ugandan] troops antedated the Protocol’, and went on to find that, apparently as a consequence, ‘this prior authorization or consent could thus be withdrawn at any time by the Government of the DRC, without further formalities being necessary’,271 i.e. without the need to denounce the Protocol formally.272 The factual circumstances of the withdrawal of consent were almost as obscure as those of its original grant, but the Court was able to conclude that ‘any earlier consent by the DRC to the presence of Ugandan troops on its territory had at the latest been withdrawn by 8 August 1998’.273

(p. 1349) The application, by analogy or otherwise, of the provisions of the Vienna Convention on the Law of Treaties to this situation throws up a difficulty with the inter-relation of Articles 54 and 56 of that text. Could the termination of the agreement of the DRC to the presence of Ugandan troops be regarded as ‘in conformity with the provisions of the treaty’, or in this case, agreement, under Article 54(a)? In the absence of specific stipulation, the agreement must be taken to have contained an implied term authorising termination by the DRC at any time. As a matter of practical politics, there need be no difficulty about this; if the consent had been embodied in a formal treaty, such a clause would no doubt have been insisted on by the DRC Government. But the case would then apparently fall within the category where a right of denunciation or withdrawal was ‘implied by the nature’ of the agreement, under Article 56(1)(b); and where this is the case, Article 56(2) requires 12 months’ notice of denunciation or withdrawal. It is doubtful whether such a precise requirement exists in the customary law which was in effect being codified by the Convention; and as the Court pointed out in its advisory opinion on Interpretation of the Agreement of 25 March 1951 between the WHO and Egypt, ‘these provisions…are based on an obligation to act in good faith and have reasonable regard to the interests of the other party to the treaty’.274 The situation was, it is suggested, that the implied terms of the agreement of 1997 were that the DRC could indeed indicate at any time that its consent to the presence of Ugandan troops was withdrawn, and Uganda would thereupon come under an obligation to arrange their prompt departure; but their presence would only constitute an internationally unlawful act at the expiration of such a period as was reasonably necessary for the Ugandan Government, acting in good faith, to make the necessary arrangements for the withdrawal.275 These were questions that did not in fact arise in the Armed Activities case, as Uganda did not proceed to withdraw its troops, claiming that their presence after the withdrawal of DRC consent was justified by considerations of self-defence.276

2.  Termination (or Suspension) of Treaties on Account of Material Breach

The question of termination for material breach cannot be entirely separated from the principle, discussed above, that ‘the claiming of rights entails submission to the corresponding obligations’;277 it is related to the maxim inadimplementi non est adimplendum.278 There is however a distinction to be made; ‘a party which disowns or (p. 1350) does not fulfil its own obligations cannot be recognized as retaining the rights which it claims to derive from the [relevant international] relationship’.279 Nevertheless, some acte juridique must intervene if the relationship is to cease to exist either permanently (termination) or temporarily (suspension); and the non-fulfilment will not in all cases give rise to the right of the other party to perform that acte.280

It would seem axiomatic that where there are two or more treaties in force between the same two parties, even if they are in pari materia, the breach, or alleged breach, of one treaty by one of the parties cannot be invoked by the other party as a ‘material breach’ of a different treaty, as grounds for terminating or suspending the latter treaty.281 It could of course happen that the relationship between the two treaties was such that the breach of the one necessarily involved a breach of the other, but in that case the claim to termination would be based on the breach of the treaty terminated. There is a contrast to be noted between termination of a treaty on the grounds of material breach of the treaty, and termination on the basis of fundamental change of circumstances: in the latter context, the party invoking the change will be debarred from doing so if the change results from that party’s own breach either of the treaty or of ‘any other international obligation owed to any other party to the treaty’.282

Nevertheless in the Gabčíkovo-Nagymaros Project case, Hungary maintained that it had been entitled to terminate the 1977 Treaty relating to the Project on the grounds that Czechoslovakia had breached not only that Treaty but other international conventions ‘and general international law’.283 The Court gave this argument short shrift:

As to that part of Hungary’s argument which was based on other treaties and general rules of international law, the Court is of the view that it is only a material breach of the treaty itself, by a State party to that treaty, which entitles the other party to rely on it as a ground for terminating the treaty. The violation of other treaty rules or of rules of general international law may justify the taking of certain measures, including countermeasures, by the injured State, but it does not constitute a ground for termination under the law of treaties.284

The parallel between action under Article 60 of the Vienna Convention, or more precisely, under the customary rule codified in the Convention, and counter-measures—or, as they used to be termed, reprisals—has been noted in the past, and generally the view has been taken that they do not overlap. Article 16 of the Draft Articles on State Responsibility prepared by Special Rapporteur Riphagen, at the end of the Part of the Draft devoted to implementation of responsibility, reserved the position by providing that the provisions of that Part should ‘not prejudge any question that may arise in regard to…the invalidity, termination and suspension of the operation of treaties’.285

(p. 1351) The Court did not, in the Gabčíkovo-Nagymaros Project case, make any findings indicative of the definition of a ‘material breach’ justifying termination of a treaty, since it decided, as mentioned above, that Hungary’s purported termination of the 1977 Treaty was invalid or ineffective for reasons not going to its justification. The Court had however found in an earlier part of its judgment that the action on the part of Czechoslovakia complained of by Hungary, once it was completed, did amount to a breach of the Treaty.286 It refused however to see in Czechoslovakia’s action a ‘repudiation’ of the Treaty, as had also been pleaded by Hungary;287 thus it would presumably not have been willing to regard that action as falling within paragraph 3(a) of Article 60 of the Vienna Convention, referring to ‘a repudiation of the treaty not sanctioned by the present Convention’ as a type of material breach. The other head of the definition, in paragraph 3(b), is ‘the violation of a provision essential to the accomplishment of the object and purpose of the treaty’.

3.  Termination on the Ground of Fundamental Change of Circumstances

The case of the Gabčíkovo-Nagymaros Project also gave the Court the opportunity to make a general statement of the principles governing the termination of a treaty on the grounds of a fundamental change of circumstances, as recognized in Article 62 of the Vienna Convention.288

A fundamental change of circumstances must have been unforeseen; the existence of the circumstances at the time of the Treaty’s conclusion must have constituted an essential basis of the consent of the parties to be bound by the Treaty. The negative and conditional wording of Article 62 of the Vienna Convention on the Law of Treaties is a clear indication moreover that the stability of treaty relations requires that the plea of fundamental change of circumstances be applied only in exceptional cases.289

The Court’s actual decision on the specific claims made by Hungary on this head was however differently expressed:

The changed circumstances advanced by Hungary are, in the Court’s view, not of such a nature, either individually or collectively, that their effect would radically transform the extent of the obligations still to be performed in order to accomplish the Project.290

The result seems to be that the Court has re-confirmed as customary law the provisions of Article 62, paragraph 1, of the Vienna Convention, expressly relied on as such by Hungary:291

A fundamental change of circumstances which had occurred with regard to those existing at the time of the conclusion of a treaty, and which was not foreseen by the (p. 1352) parties, may not be invoked as a ground for terminating or withdrawing form the treaty unless:

  1. (a)  the existence of those circumstances constituted an essential basis of the consent of the parties to be bound by the treaty; and

  2. (b)  the effect of the change is radically to transform the extent of obligations still to be performed under the treaty.

The actual changes specified by Hungary as grounds for termination were ‘profound changes of a political nature, the Project’s diminishing economic viability, the progress of environmental knowledge and the development of new norms and prescriptions of international environmental law’.292 As regards political changes, it should be recalled that there was broad agreement at the Vienna Conference that ‘a change in the attitude or policy of a Government could never be invoked’ as a ground of termination of a treaty.293

The first two grounds were dismissed essentially on the facts; but the last is of more general interest. The position of Hungary can perhaps be simply summed up as ‘if we’d known in 1977 what we now know about the environmental impact of the Project, we would never have adopted it’; a very reasonable position, but can it be made to fit the requirements of ‘fundamental change of circumstances’? The Court rejected this particular contention for two reasons: first, that it did not consider ‘that new developments in the state of environmental knowledge and of environmental law can be said to have been completely unforeseen’; and secondly ‘[w]hat is more, the formulation of Articles 15, 19, and 20 [of the 1977 Treaty], designed to accommodate change, made it possible for the parties to take account of such developments and to apply them when implementing the treaty provisions’.294

In the previous article on this subject, attention was drawn to a distinction which appeared to exist between the requirements for a termination on the basis of changed circumstances contemplated by the Court in the Fisheries Jurisdiction cases, and those of Article 62 of the Vienna Convention. The Convention refers to the ‘change of circumstances’ as one ‘which was not foreseen by the parties’; but the Fisheries Jurisdiction judgment apparently contemplated a change of circumstances of which the impact on the obligations of the party affected had not been foreseen. In that article it was therefore observed that:

Clearly a change of circumstances which was totally unforeseeable, but which has occurred, may yet have no, or minimal, effect as regards the onerousness of the parties’ obligations…; on the other hand, events which the parties could have foreseen, and perhaps even did foresee, might turn out to have an unexpected effect on their obligations.295

In that case the Court was not applying the Vienna Convention, nor even regarding Article 62 as an expression of customary law, so it was free to take this view of the (p. 1353) foreseeability question. In the Gabčíkovo-Nagymaros Project case, the Court’s options were more limited: ‘[a] fundamental change of circumstances must have been unforeseen’.296 The Court recognized that, consistently with previous decisions, that the Convention had codified existing customary law, and that ‘in many respects297 this applies to the provisions of the Vienna Convention concerning the termination…of treaties, set forth in Articles 60 to 62’.298 Nevertheless, it appears to have recognized the force of the distinction; the environmental changes were treated as not themselves ‘completely unforeseen’, but in summing up its attitude to all the changes relied on by Hungary (including the political and economic changes), it considered, as noted above, that they were ‘not of such a nature…that their effect would radically transform the extent of the obligations still to be performed to accomplish the Project’.299

In its 1997 decision, the Court added another condition for the invocation of fundamental change of circumstances: that that change could not have been accommodated within the structure of the treaty, through mechanisms there provided for adjustment of the parties’ rights and obligations.300 This chimes well with the general policy of the law of regarding termination of a treaty as a last resort; but as the Gabčíkovo-Nagymaros Project case shows, there may well be difficulties if disagreements between the parties prevent the adjustment provisions from taking effect.

A question that remains unsettled is whether the ‘circumstances’ contemplated by Article 63 are purely factual, or whether a change in the relevant international law might also qualify as such. The text of the Article gives no guidance; but in the travaux préparatoires of the ILC, there are references to an intention not to exclude the possibility of a change of legal regime impossible of performance.301 There is of course a distinction between circumstances rendering a treaty impossible of performance (dealt with in Article 61 of the Vienna Convention) and a fundamental change of circumstances (dealt with in Article 62);302 however, there does not appear to be any vital difference between the two situations as regards the possible impact of changes in the law.

(p. 1354) It may be recalled that the Court in the Fisheries Jurisdiction cases was faced with a contention by Iceland that the relevant international law had developed since the 1961 Exchange of Notes was concluded; since Iceland was not appearing in the proceedings, this argument was not couched in formal legal terms. However the treaty instrument which, in Iceland’s contention, was affected by the change, the 1961 Exchange of Notes, was purely a dispute settlement agreement; if the law on fisheries jurisdiction had changed, Iceland would be able to rely on the change as a matter of the merits of the dispute, but this would be irrelevant to the continuing force of the Exchange of Notes—and the Court made an express finding to that effect.303 The Court examined the Icelandic position in the light of ‘fundamental change of circumstances’ as affecting the operation of the Exchange of Notes only in relation to factual changes, such as the development of new fishing techniques. Hungary in the Project case relied on ‘changes in environmental knowledge and law’ in support of its reliance on ‘fundamental change of circumstances’, but emphasized that these in themselves would not have been enough; it was the combination of political, economic, environmental and legal circumstances that was relied on.304

An argument against the inclusion of changes in the law in the category of relevant ‘circumstances’ for purposes of Article 62 of the Vienna Convention might be based on Article 64 of the Convention: if a treaty is terminated by the emergence of a peremptory norm of international law with which it is not consistent, can it be deduced a contrario that no other change in the law has any effect on the continued operation of the treaty?305 Something of the sort was argued by Slovakia, but rather in response to a contention by Hungary that the 1977 Treaty had become impossible of performance.306 However, the characteristic (and controversial) feature of Article 64 is its automatic operation; it does not need to be invoked by either party, and the invalidity of the treaty is independent of the wishes or intentions of either party or both parties.307 For this reason the decision in the Gabčíkovo-Nagymaros Project case has been criticized inasmuch as the Court declined to investigate ex officio whether any jus cogens rules of environmental law had emerged, contenting itself with noting that ‘[n]either of the Parties contended’ that such was the case.308 There seems no reason of principle why a change in the applicable international law, not having the quality of jus cogens, might not ‘radically transform the obligations still to be performed’ by a party to the treaty; the difficulty is to imagine circumstances in which this might be so.

In the case of the Gabčíkovo-Nagymaros Project, Hungary also presented an argument to the effect, as quoted by the Court, that ‘subsequently imposed requirements of international law in relation to the protection of the environment precluded performance of the Treaty’, because ‘[t]he previously existing obligation not to cause substantive damage to the territory of another State had…evolved into an erga omnes obligation of prevention of damage pursuant to the “precautionary principle” ’.309 The Court continued its (p. 1355) statement of Hungary’s argument: ‘[o]n this basis, Hungary argued, its termination was “forced by the other party’s refusal to suspend work on Variant C”.’310 Since it was not argued that any damage would be caused by the Project works to any territories other than those of the parties, it is at first sight unclear how this assertion, even if correct, would affect the Treaty. However, Hungary in fact recalled in its Memorial that when terminating the Treaty it had invoked, inter alia, the fact that ‘subsequently imposed requirements of international law in relation to protection of the environment precluded performance of the Treaty’, and noted that this was ‘relevant to’ the other grounds relied on, particularly that of fundamental change of cir- cumstances.311 The Memorial then explained that the important development in international law was the recognition that it was prevention of harm that mattered312 (the possible erga omnes character of the rule being apparently irrelevant in a bilateral relationship), and hence:

If Czechoslovakia was obliged under general international law not to carry out activities on its territory that would cause serious or substantial harm to Hungary, then Hungary was entitled to take action to remove any pretext for such conduct.313

This is an argument that the Court did not deal with expressly, but it amounts to saying that fundamental change of circumstances may cover ‘subsequently imposed requirements of international law’, ie, that Article 62 of the Vienna Convention was not limited to physical changes.

3A.  Impossibility of Performance

As though anxious to provide the Court with an opportunity of reviewing the full gamut of grounds for termination of treaties contemplated by the Vienna Convention, Hungary in the case of the Gabčíkovo-Nagymaros Project also relied on the principle of impossibility of performance (Article 61 of the Convention). Since the Vienna Convention was not as such applicable to the 1977 Treaty between the parties (which was concluded before the entry into force of the Vienna Convention between the parties), the Court was in fact being called upon to rule on the question of impossibility in customary law, in the light of the Convention. The Court however treated the matter as though Article 61 were the exclusive source of law on the point; it observed immediately that in the Convention this ground is limited to cases in which the impossibility ‘results from the permanent disappearance or destruction of an object indispensable for the execution of the treaty’; and it is to be noted that the word ‘object’ here clearly has its sense of a tangible article, not—as in the hallowed phrase ‘the object and purpose of the treaty’—a purposive sense.314 Although Hungary argued that the ‘object’ did not have to be a physical object,315 its claim, as summarised by the Court, does seem to hover between these two senses: it contended that

the essential object of the Treaty—an economic joint investment which was consistent with environmental protection and which was operated by the two contracting parties (p. 1356) jointly—had permanently disappeared and that the Treaty had thus become impossible to perform.316

The term ‘impossible’ was also used in Hungary’s contentions in a sense other than that of ‘that which cannot be done’, but something nearer to ‘that which it would be absurd or unreasonable to do’, since Hungary also complained that it could not be ‘obliged to fulfill a practically impossible task, namely to construct a barrage system on its own territory that would cause irreparable environmental damage.’317

The Court’s ruling on this was as follows:

It is not necessary for the Court to determine whether the term “object” in Article 61 can also be understood to embrace a legal régime as in any event, even if that were the case, it would have to conclude that in this instance that régime had not definitively ceased to exist. The 1977 Treaty—and in particular its Articles 15, 19 and 20—actually made available to the parties the necessary means to proceed at any time, by negotiation, to the required readjustments between economic imperatives and ecological imperatives.318

Some lines earlier it had however already indicated a doubt whether the intention of the Convention text had been to contemplate anything other than the disappearance of a physical object, by noting that:

During the [Vienna] conference, a proposal was made to extend the scope of the article by including in it cases such as the impossibility to make certain payments because of serious financial difficulties…Although it was recognized that such situations could lead to a preclusion of the wrongfulness of non-performance by a party of its treaty obligations, the participating States were not prepared to consider such situations to be a ground for terminating or suspending a treaty, and preferred to limit themselves to a narrower concept.319

The Court however added a further reason why Hungary’s reliance on supervening impossibility of performance could not be accepted:

The Court would add that, if the joint exploitation of the investment was no longer possible, this was originally because Hungary did not carry out most of the works for which it was responsible under the 1977 Treaty; Article 6i, paragraph 2, of the Vienna Convention expressly provides that impossibility of performance may not be invoked for the termination of a treaty by a party to that treaty when it results from that party’s own breach of an obligation flowing from that treaty.320

The phenomenon of multiplicity of reasons in a judgment in support of a single conclusion, which is probably to be attributed to the collegiate nature of the Court, sometimes makes it difficult to extract a true ratio decidendi; but in this case, the essential (and the most specific) reason employed would seem to be that performance of a treaty is not to be deemed impossible, for purposes of Article 6i, if the treaty itself provides for its being adapted to the circumstances relied on as showing impossibility; in such case, at the very (p. 1357) least, the onus is upon the party claiming impossibility to show that those provisions would not have rescued the achievement of compliance with the treaty.

4.  Failure of Consideration as a Ground for Termination of Treaties?

Attention has been drawn above to an aspect of the Gabčíkovo-Nagymaros Project case which bears some resemblance to an application of the concept of failure of consideration in Anglo-American contract law.321

5.  Procedural Requirements on Termination of Treaty

In the preceding article on this aspect, reference was made to the provisions (Articles 65 to 68) of the Vienna Convention concerning ‘Procedure’, and specifically ‘Procedure to be followed with respect to invalidity, termination, withdrawal from or suspension of the operation of a treaty’. How rapidly the law has developed since that time, under the influence of the Convention itself is apparent from a comparison of the view stated in that article that ‘[i]t appears evident that, except to the extent that Article 33 of the Charter may be taken to reflect customary law, these provisions of the Vienna Convention are de lege ferenda…’,322 with the Court’s observation in the case of the Gabčíkovo-Nagymaros Project that:

Both Parties agree that Articles 65 to 67 of the Vienna Convention on the Law of Treaties, if not codifying customary law, at least generally reflect customary international law and contain certain procedural principles which are based on an obligation to act in good faith.323

The relevance of the rules of customary law that thus corresponded to these provisions was in view of the termination, or purported termination, by Hungary of the 1977 Treaty concerning the Project. This was effected by a Declaration transmitted to the Government of Czechoslovakia on 19 May 1992, accompanied by a letter explaining that the immediate cause for the termination was Czechoslovakia’s refusal, expressed in a letter of 23 April 1992, to suspend works known as ‘Variant C’ during mediation efforts of the Commission of the European Communities.324 The termination was stated to be effective as of 25 May 1992—a mere 6 days later.

When the Court considered the question of the length of notice of termination, in the light of the customary law corresponding to Article 65 of the Vienna Convention, it had already, in the preceding paragraph of its judgment, concluded that ‘the notification of termination by Hungary was premature’, inasmuch as ‘[n]o breach of the Treaty by Czechoslovakia had yet taken place’ and consequently ‘Hungary was not entitled to invoke any such breach of the Treaty as a ground for terminating when it did’.325 The notice of termination was therefore presumably a nullity; and one might question the usefulness of examining whether it might also be vitiated by shortness of the (p. 1358) period of notice.326 However, the Court did not in fact rule on the question whether the Declaration, had it been justified by Czechoslovakia’s actions, might have been given to take effect on too short notice. The Court said:

The termination of the Treaty by Hungary was to take effect six days after its notification. On neither of these dates had Hungary suffered injury resulting from acts of Czechoslovakia. The Court must therefore confirm its conclusion that Hungary’s termination of the Treaty was premature.327

The length of the notice given thus turns out to be quite irrelevant: if Hungary had given a much longer period of notice, one that would satisfy whatever the requirements of international law on the point may be, it would still have been premature and invalid if at the date of its expiry Hungary had not yet suffered ‘injury resulting from acts of Czechoslovakia’. On the face of the judgment, the Court not only gives no ruling on what would be an adequate period of notice; its finding that, as the parties agreed, Article 65 of the Vienna Convention ‘reflected customary international law’ was otiose. However, it should not be overlooked that Judge Herczegh, in his dissenting opinion, took the point of alleged short notice, and drew attention to the qualification in Article 65, paragraph 2, of the Convention: that text requires effective termination to be ‘after the expiration of a period which, except in cases of special urgency, shall not be less than three months after the receipt of the notification’. In Judge Herczegh’s view, ‘in the face of very visible progress in the building of Variant C, Hungary was manifestly in such a situation of “special urgency”.’328 The Court may thus be taken to have been tacitly rejecting Judge Herczegh’s view on this point.

6.  Desuetude

In the earlier article, under this heading, the contention of France in the Nuclear Tests cases was discussed, that the 1928 General Act could no longer serve as a basis for the jurisdiction of the Court, having fallen into desuetude.329 While the Court made no finding on the point, the views of those judges who discussed it in their opinions tend to support the view of the International Law Commission that if a treaty can cease to be effective after a long lapse of time, it can only be because a tacit consent of the parties can be discerned in this circumstance. It was there observed that non-recourse to a jurisdictional title, for example a declaration under the Optional Clause of the Court’s Statute, cannot be relied on to suggest that the title has fallen into desuetude, in view of the sporadic and tangential way in which such titles may be relied on.

In the case of the Aerial Incident of 10 August 1999, it was argued by Pakistan that a reservation in India’s Optional Clause declaration was ‘obsolete’ and thus could not be relied on.330 Such a reservation, and indeed a declaration under the optional (p. 1359) clause, partakes of the nature of a unilateral act; but one which is embedded in a treaty relationship,331 so that (for example) the rules of interpretation of treaties may mutatis mutandis be applied to the interpretation of declarations.332 The Court did not consider whether desuetude or obsolescence was a concept applicable to declarations; Judge Al-Khasawneh in his dissenting opinion noted that it had been argued that ‘the doctrine of obsolescence does not apply to unilateral acts’, and suggested that that view might be questioned inasmuch as it was

based on the assumption that what starts as a unilateral undertaking goes on being so even when it is transformed into mutual arrangements, raising in other parties to the optional clause system reasonable expectations not dissimilar to those raised under treaty relations.333

The reservation was the Commonwealth clause, excluding from the acceptance of jurisdiction disputes between the declarant State and other members of the British Commonwealth. The suggestion that that clause ‘could easily [be] regarded as obsolete’ had been thrown out by Judge Ago in 1992 in his dissenting opinion in the case of Certain Phosphate Lands in Nauru. The reason he gave, which was later to be invoked by Pakistan, was that the clause had ‘originally been inserted in the [United Kingdom] declaration in anticipation of the establishment of a special court for the Commonwealth’ and ‘that expectation has never been fulfilled’.334 In the case of the Indian declaration, as the Court noted, the reservation had been consistently included in successive declarations deposited by India following its independence,335 the most recent dating from 1974, a date at which (though the Court did not spell this out) it had become undeniably evident that the special court for the Commonwealth was never going to be created.336 Unsurprisingly, the Court rejected the argument of Pakistan, observing that:

While the historical reasons for the initial appearance of the Commonwealth reservation in the declarations of certain States under the optional clause may have changed or disappeared, such considerations cannot, however, prevail over the intention of a declarant State, as expressed in the actual text of its declaration. India has repeatedly made clear that it wishes to limit in this manner the scope ratione personae of its acceptance of the Court’s jurisdiction. Whatever may have been the reasons for this limitation, the Court is bound to apply it.337

This decision, while undoubtedly correct and appropriate to the case before the Court, does not afford the assistance that might be hoped for on the question of desuetude. If (p. 1360) India’s declaration had stood unchanged since 1947, and if at that time the original justification for the inclusion of the Commonwealth reservation had been still in existence, what effect, if any, could the subsequent disappearance of that justification have on the declaration and the reservation? On the actual facts of the case, India’s intentions had not altered and were not in doubt: to maintain the reservation. The purpose underlying it may perhaps have been no more than force of habit, or ex abundanti cautela; but perhaps also India maintained the clause in view of the political developments making disputes with Pakistan far from unlikely. This indeed was suggested by Pakistan as the reason for India’s maintenance of the reservation,338 a contention accepted by Judge Al-Khasawneh.339

In view of the emphasis on consent in relation to desuetude of bilateral treaties, one may ask, not whether a reservation can fall into desuetude, but rather whether a reservation could be abandoned by its maker; and whether such abandonment might be inferred even in the absence of formal withdrawal. Perhaps the only circumstances in which this particular reservation might have been treated as abandoned would be if on a number of occasions proceedings before the Court had been brought against India by other Commonwealth countries, and on each occasion India had refrained from relying on the reservation, and had made no statement reserving its position. The case would be even stronger if it could be shown that there was a general tacit consensus among Commonwealth States that the reservation should not be invoked. This however is somewhat speculative: what is clear is that in the field of Optional Clause reservations, and possibly generally in the field of treaty-law, the Court does not regard as applicable the maxim cessat ratio legis, cessat lex ipsa.


256  For the parallel claim by Hungary to have suspended the operation of the Treaty in 1989, see above, Chapter III, Section 1, and Section 2 of the present Chapter.

257  [1997] ICJ Rep 62–63, para 100. This of course in fact amounts to a re-statement of Article 56 of the Vienna Convention itself, but with the omission of any reference to the possibility that ‘a right of denunciation or withdrawal’ might have been ‘implied by the nature of the treaty’. In view of the nature of the Project, the Court probably thought that the fact that this was not so in the case before it was too obvious to mention. On the background to Article 46, see Fitzmaurice and Elias, Contemporary Issues in the Law of Treaties, 354–358.

258  Ibid, 62, para 99; the Court added ‘[o]n this, the Parties, too, were broadly in agreement.’

259  See further on this, Section 5 below.

260  The distinction was not accepted by Judge Ranjeva (dissenting opinion, [1997] ICJ Rep 173).

261  [1997] ICJ Rep 67, para 110.

262  [1980] ICJ Rep 96, para 49.

263  It seems that the latter may have been the main consideration, since the Court did not quote a slightly earlier passage in the WHO Agreement case, to the effect that the party which wished to terminate the agreement was under a duty ‘to give a reasonable period of notice to the other party for the termination of the existing situation’: ibid, 95–96, para 49.

264  [1997] ICJ Rep 198.

265  The argument of the duty of limitation of damage was in fact employed by Slovakia to argue that Czechoslovakia had been not merely entitled but obliged to carry out Variant C in order to mitigate the damage caused by Hungary’s effective withdrawal from the Project ([1997] ICJ Rep 51–52). The Court held that ‘[w]hile this principle might thus provide a basis for the calculation of damages, it could not, on the other hand, justify an otherwise wrongful act’ (ibid, 55).

266  [1997] ICJ Rep 198.

267  Chapter IV, Section 2.

268  According to counsel involved in the case (private communication), no such legislation existed, so that this line of argument was probably not available; but the general point, it is suggested, remains valid.

269  [2005] ICJ Rep 196–197, para 45. The question of consent to the presence of troops also arose in relation to the period after 10 July 1999, the date of the conclusion of the Lusaka Agreement between the two parties. The issues there however did not relate to termination of consent, but to whether an agreement for orderly withdrawal of the troops constituted a consent to their presence, either retrospectively, or prospectively for the period laid down for the process of withdrawal. See ibid, 210–212, paras. 98–105.

270  Ibid, 197, para 46.

271  Ibid, emphasis added.

272  Uganda had argued that such a denunciation was necessary to terminate the consent: ibid, 198, para 50.

273  Ibid, 199, para 53.

274  [1980] ICJ Rep 95, para 47

275  However, it should be noted that when in 1999 the Lusaka Agreement, two Disengagement Plans, and the Luanda Agreement of 6 September 2002 laid down precise arrangements for the withdrawal of the Ugandan troops, the court was not willing to see in these instruments a consent to their presence during the period laid down for the withdrawal: ibid, 212, para 105. This finding was strongly and (it is suggested) rightly criticized by Judge Parra-Aranguren, [2005] ICJ Rep 294, para 8, who drew attention to the ‘impossible legal situation’ so created for Uganda. No practical consequences of the finding seem to have been drawn in the Judgment; but it may have implications in the field of reparations, to be dealt with, if necessary, in further proceedings. cf. also the observations in the Case Concerning the Gabčíkovo-Nagymaros Project discussed in section 5 of this chapter, below.

276  [2005] ICJ Rep 213 ff., paras 106 ff.

277  See above Chapter III, Section 2.

278  Cf. B Simma, ‘Reflections on Article 60 of the Vienna Convention on the Law of Treaties and its Background in General International Law’, 20 Österreichische Zeitschrift für öffentliches Recht und Völkerrecht (1970), 20.

279  Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa) notwithstanding Security Resolution 276 (1970), Advisory Opinion, [1971] ICJ Rep 46, para 91.

280  For this reason it does not seem correct to present this dictum in the South West Africa case (previous note) as a pronouncement ‘concerning material breach’, as in Fitzmaurice and Elias, Contemporary Issues in the Law of Treaties, 363–364.

281  Note however the argument advanced by some States in the Namibia case that South Africa’s mandate could be terminated on the ground of, inter alia, breaches of the UN Charter and the Universal Declaration of Human Rights: commented on by J Klabbers, ‘Some Problems Regarding the Object and Purpose of Treaties’ (1997) 8 Finnish Yearbook of International Law 142.

282  Vienna Convention on the Law of Treaties, Article 62, para 2(b).

283  [1997] ICJ Rep 61, para 96.

284  Ibid, 65, para 106.

285  UN doc. A/CN/4/389, 15. At its 37th Session the ILC considered that the relationship between the draft and the Vienna Convention needed to be ‘further clarified’ (A/40/10, 24, para 156) and the draft Article was dropped in the Rapporteur’s next Report (A/CN.4/397).

286  [1997] ICJ Rep 54, para 78.

287  Ibid, 68, para 114.

288  The existence and nature in customary law of the clausula rebus sic stantibus has been controversial, particularly as regards the question whether or not (as the term ‘clausula’ implies), it is to be regarded as subjective, based on an implied term in treaties. on the practice prior to the adoption of the Vienna Convention, see for example DF Vagts, ‘Rebus Revisited: Changed Circumstances in Treaty Law’ (2004–2005) 43 Columbia Journal of Transnational Law 459, and G Dahm, Völkerrecht (1988), II, 742.

289  [1997] ICJ Rep 65, para 104.

290  Ibid.

291  See Ibid, 59–60, para 95. The Court had already held in the two Icelandic Fisheries Jurisdiction cases that Article 62 could be regarded ‘in many respects’ as codifying customary law: [1973] ICJ Rep 18, para 36; 63, para 36.

292  [1997] ICJ Rep 64, para 104, referring to ibid, 60, para 95.

293  ILC Yearbook 1966-II, 259; and see I M Sinclair, The Vienna Convention on the Law of Treaties (1984), 194–195.

294  Ibid, 64–65, para 104. However, one of the grounds on which Hungary claimed that Czechoslovakia had committed material breaches of the Treaty was precisely that it ‘had violated Articles 15, 19 and 20 of the Treaty by refusing to enter into negotiations with Hungary’ in order to adapt the Project to ‘new scientific and legal developments regarding the environment’: ibid, 65, para 107.

295  (1992) BYIL 1, 80–81.

296  [1997] ICJ Rep 65, para 104.

297  A formula which Rosenne calls ‘an obscure form of phrase which may mean much or very little’: Breach of Treaty, 32.

298  [1997] ICJ Rep 38, para 46 (footnotes omitted).

299  Ibid, 65, para 104, emphasis added.

300  In the previous article on this subject, it was suggested that the concept formerly known as the rebus sic stantibus rule was subject to a qualification excluding its operation where the parties in their treaty had ‘made other provision for the possible events which might justify invocation of the rule’ (1992) BYIL 1, 79. For an analogous finding as to the relevance of the terms of the treaty to issues in some sense ‘outside’ it, cf. the Court’s finding in the Military and Paramilitary Activities case that ‘an act cannot be said to be one calculated to deprive a treaty of its object and purpose, or to impede its due performance, if the possibility of that act has been foreseen in the treaty itself, and it has been expressly agreed that the treaty ‘shall not preclude’ the act…’: [1986] ICJ Rep 136, para 272.

301  See for example H Waldock in ILC Yearbook 1963-I, 248.

302  There is of course a degree of overlap between the two concepts (cf. Jennings and Watts, Oppenheim’s International Law II, 1304, fn.1). Cf. also the decision of the European Court of Justice in A. Racke GmbH v. Hauptzollamt Mainz (Case C-162/96), in which a suspension of tariff concessions under a treaty régime between Germany and Yugoslavia on the grounds of the outbreak of hostilities in Yugoslavia was challenged on the ground (inter alia) that ‘a certain volume of trade had to continue with Yugoslavia and that the Community could have continued to grant tariff concessions’; the Court ruled that ‘that application of the customary international law rules in question does not require an impossibility to perform obligations, and that there was no point in continuing to grant preferences, with a view to stimulating trade, in circumstances where Yugoslavia was breaking up’ (para 57 of the Judgment).

303  [1973] ICJ Rep 16, para 30; 61, para 30.

304  See, e.g., Hungary’s Reply, para 3.78.

305  Hungary in fact originally argued that subsequent norms of environmental law took precedence over an earlier treaty on the basis of lex posterior derogat priori: see the Hungarian Declaration of Termination of the Treaty, Hungarian Memorial, Vol. 4, Annex 82, 182, para 6.

306  [1997] ICJ Rep 62, para 97.

307  This is clear from the modifications made by the ILC to the drafts of G Fitzmaurice and H Waldock, which had proposed a faculty for any party to call for the termination of the treaty: ILC Yearbook 1963-II, 211.

308  [1997] ICJ Rep 67, para 112; for criticism see Orakhelashvili, Peremptory Norms in International Law, 498.

309  [1997] ICJ Rep 62, para 97.

310  Ibid.

311  Hungarian Memorial, paras. 10.91–10.92.

312  A point which is not made clear in the Court’s summary of the argument, quoted above.

313  Hungarian Memorial, para 10. 96.

314  The ILC contemplated such examples as the disappearance of an island, the drying-up of a river, or the destruction of a dam.

315  [1997] ICJ Rep 59, para 94.

316  Ibid, para 103.

317  Ibid, 59, para 94, emphasis added. For some commentators, the plea of impossibility of performance is an application of the concept of force majeure rendering non-performance ‘non fautive’ (see, e.g. P Daillier and A Pellet, Droit International Public (5th edn, 1999), 305, para 206).

318  Ibid, 63–64.

319  [1997] ICJ Rep 63, para 102, citing Official Records of the United Nations Conference on the Law of’ Treaties, First Session, Vienna, 26 March-24 May 1968, A/CONF.39/11, Summary records of the plenary meetings and of the meetings of the Committee of the Whole, 62nd Meeting of the Committee of the Whole, 361–365.

320  Ibid, 64, para 103.

321  See above Chapter II, Section 1(2).

322  (1992) BYIL 1, 86.

323  [1997] ICJ Rep 66, para 109. The Court cited its advisory opinion in the case of the Interpretation of the Agreement of 25 March 1951 between the WHO and Egypt, [1980] ICJ Rep 96, para 49, relating to Article 56 of the Convention, discussed in the previous article.

324  [1997] ICJ Rep 58, para 91.

325  Ibid, 66, para 108.

326  The Court also proceeded to find that when Czechoslovakia did commit an internationally wrongful act by ‘putting into operation Variant C’, this was ‘as a result of Hungary’s own wrongful conduct’, and that ‘Hungary, by its own conduct, had prejudiced its right to terminate the Treaty’: ibid, 67, para 110. This argument is introduced almost as an afterthought, but it would seem to have logical priority: if Hungary ‘had prejudiced its right to terminate the Treaty’, then whatever the formal validity of its notification, it would have been substantially a nullity.

327  [1997] ICJ Rep 66–67, para 109.

328  Ibid, para 198.

329  (1992) BYIL 1, 94–96, citing ICJ Pleadings in the case, Vol. II, 354.

330  [2000] ICJ Rep 30, para 41. A point the Court was not in the event called upon to decide was whether, if the reservation was ineffective for, as it were, desuetude, the result would be that the whole declaration would be invalid, as suggested by Judge Lauterpacht in respect of the Connally reservation in the Certain Norwegian Loans case [1957] ICJ Rep 57–59.

331  Cf. Military and Paramilitary Activities in and against Nicaragua, [1984] ICJ Rep 418, para 60.

332  See the case of Fisheries Jurisdiction (Spain v. Canada), [1998] ICJ Rep 453, para 46, discussed in the previous article, (2006) BYIL 1, 27–28.

333  [2000] ICJ Rep 50, para 5.

334  [1992] ICJ Rep 327, para 5.

335  And in fact even before independence, when in 1929 the Commonwealth countries accepted the Optional Clause of the Statute of the Permanent Court (LNTS, Vol. 6, 379).

336  The idea that the Judicial Committee of the Privy Council might serve as an inter-Commonwealth court was linked with the inter se doctrine, that relations between the Commonwealth countries were not relations governed by international law in the same way as those between States (cf. the Report of the 1926 Imperial Conference, British Command Papers, Cmd. 2768, Section V). For the background generally, see R Jennings, ‘The Commonwealth and International Law’, (1953) BYIL 320; W Dale, The Modern Commonwealth (1983).

337  [2000] ICJ Rep 31, para 44.

338  Ibid, 27, para 30 in fine.

339  Ibid, 51, para 11.