. . .
The present case arose out of the signature, on 16 September
1977, by the Hungarian People's Republic and the Czechoslovak
People's Republic, of a treaty "concerning the construction
and operation of the Gabcíkovo-Nagymaros System of Locks"
(hereinafter called the "1977 Treaty"). The names of
the two contracting States have varied over the years; hereinafter
they will be referred to as Hungary and Czechoslovakia. The 1977
Treaty entered into force on 30 June 1978.
.....It provides for the construction
and operation of a System of Locks by the parties as a "joint
investment". According to its Preamble, the barrage system
was designed to attain "the broad utilization of the natural
resources of the Bratislava-Budapest section of the Danube river
for the development of water resources, energy, transport, agriculture
and other sectors of the national economy of the Contracting
Parties". The joint investment was thus essentially aimed
at the production of hydroelectricity, the improvement of navigation
on the relevant section of the Danube and the protection of the
areas along the banks against flooding. At the same time, by
the terms of the Treaty, the contracting parties undertook to
ensure that the quality of water in the Danube was not impaired
as a result of the Project, and that compliance with the obligations
for the protection of nature arising in connection with the construction
and operation of the System of Locks would be observed.
The Danube is the second longest river in Europe, flowing along
or across the borders of nine countries in its 2,860-kilometer
course from the Black Forest eastwards to the Black Sea. For
142 kilometers, it forms the boundary between Slovakia and Hungary.
The sector with which this case is concerned is a stretch of
approximately 200 kilometers, between Bratislava in Slovakia
and Budapest in Hungary. . . .
The Danube has always played a vital part in the commercial and
economic development of its riparian States, and has underlined
and reinforced their interdependence, making international co-operation
essential. Improvements to the navigation channel have enabled
the Danube, now linked by canal to the Main and thence to the
Rhine, to become an important navigational artery connecting
the North Sea to the Black Sea. In the stretch of river to which
the case relates, flood protection measures have been constructed
over the centuries, farming and forestry practised, and, more
recently, there has been an increase in population and industrial
activity in the area. The cumulative effects on the river and
on the environment of various human activities over the years
have not all been favourable, particularly for the water régime.
.....Only by international co-operation
could action be taken to alleviate these problems. Water management
projects along the Danube have frequently sought to combine navigational
improvements and flood protection with the production of electricity
through hydroelectric power plants. The potential of the Danube
for the production of hydroelectric power has been extensively
exploited by some riparian States. The history of attempts to
harness the potential of the particular stretch of the river
at issue in these proceedings extends over a 25-year period culminating
in the signature of the 1977 Treaty.
Article 1, paragraph 1, of the 1977 Treaty describes the principal
works to be constructed in pursuance of the Project. It provided
for the building of two series of locks, one at Gabcíkovo
(in Czechoslovak territory) and the other at Nagymaros (in Hungarian
territory), to constitute "a single and indivisible operational
system of works...."
Thus, the Project was to have taken the form of an integrated
joint project with the two contracting parties on an equal footing
in respect of the financing, construction and operation of the
works. Its single and indivisible nature was to have been realized
through the Joint Contractual Plan which complemented the Treaty.
In particular, Hungary would have had control of the sluices
at Dunakiliti and the works at Nagymaros, whereas Czechoslovakia
would have had control of the works at Gabcíkovo.
As a result of intense criticism which the Project had generated
in Hungary, the Hungarian Government decided on 13 May 1989 to
suspend the works at Nagymaros pending the completion of various
studies which the competent authorities were to finish before
31 July 1989. On 21 July 1989, the Hungarian Government extended
the suspension of the works at Nagymaros until 31 October 1989,
and, in addition, suspended the works at Dunakiliti until the
same date. Lastly, on 27 October 1989, Hungary decided to abandon
the works at Nagymaros and to maintain the status quo at Dunakiliti.
. . . The Court notes that it has been asked to determine what
are the legal effects of the notification given on 19 May 1992
of the termination of the Treaty. It will consequently confine
itself to replying to this question.
On 19 May 1992, the Hungarian Government transmitted to the Czechoslovak
Government a Declaration notifying it of the termination by Hungary
of the 1977 Treaty as of 25 May 1992. In a letter of the same
date from the Hungarian Prime Minister to the Czechoslovak Prime
Minister, the immediate cause for termination was specified to
be Czechoslovakia's refusal, expressed in its letter of
23 April 1992, to suspend the work on Variant C [Czechoslovakia's
unilateral diversion of the Danube on its territory, followed
by its construction of an overflow dam and levee linking that
dam to a bypass canal] during mediation efforts of the Commission
of the European Communities. In its Declaration, Hungary stated
that it could not accept the deleterious effects for the environment
and the conservation of nature of the implementation of Variant
C which would be practically equivalent to the dangers caused
by the realization of the original Project. It added that Variant
C infringed numerous international agreements and violated the
territorial integrity of the Hungarian State by diverting the
natural course of the Danube.
During the proceedings, Hungary presented five arguments in support
of the lawfulness, and thus the effectiveness, of its notification
of termination. These were the existence of a state of necessity;
the impossibility of performance of the Treaty; the occurrence
of a fundamental change of circumstances; the material breach
of the Treaty by Czechoslovakia; and, finally, the development
of new norms of international environmental law. Slovakia contested
each of these grounds.
On the first point, Hungary stated that, as Czechoslovakia had
"remained inflexible" and continued with its implementation
of Variant C, "a temporary state of necessity eventually
became permanent, justifying termination of the 1977 Treaty".
Slovakia, for its part, denied that a state of necessity existed
on the basis of what it saw as the scientific facts; and argued
that even if such a state of necessity had existed, this would
not give rise to a right to terminate the Treaty under the Vienna
Convention of 1969 on the Law of Treaties.
Hungary's second argument relied on the terms of Article 61 of
the Vienna Convention [regarding the claimed supervening impossibility
of performance] .... Hungary declared that it could not be "obliged
to fulfill a practically impossible task, namely to construct
a barrage system [i.e., a man-made barrier] on its own
territory that would cause irreparable environmental damage".
It concluded that
"By May 1992 the essential object of the Treaty--an economic
joint investment which was consistent with environmental protection
and which was operated by the two parties jointly--
had permanently disappeared, and the Treaty had thus become impossible
.....In Hungary's view, the "object
indispensable for the execution of the treaty", whose disappearance
or destruction was required by Article 61 of the Vienna Convention,
did not have to be a physical object, but could also include,
in the words of the International Law Commission, "a legal
situation which was the raison d'être of
the rights and obligations". Slovakia claimed that Article
61 was the only basis for invoking impossibility of performance
as a ground for termination, that paragraph 1 of that Article
clearly contemplated physical "disappearance or destruction"
of the object in question, and that, in any event, paragraph
2 precluded the invocation of impossibility "if the impossibility
is the result of a breach by that party ... of an obligation
under the treaty".
As to "fundamental change of circumstances", Hungary
relied on Article 62 of the Vienna Convention on the Law of Treaties
.....Hungary identified a number
of "substantive elements" present at the conclusion
of the 1977 Treaty which it said had changed fundamentally by
the date of notification of termination. These included the notion
of "socialist integration", for which the Treaty had
originally been a "vehicle", but which subsequently
disappeared [after the Cold War]; the "single and indivisible
operational system", which was to be replaced by a unilateral
scheme [by Czechoslovakia's Variant C interpretation of the 1977
treaty]; the fact that the basis of the planned joint investment
had been overturned by the sudden emergence of both States into
a market economy; the attitude of Czechoslovakia which had turned
the "framework treaty" into an "immutable norm";
and, finally, the transformation of a treaty consistent with
environmental protection into "a prescription for environmental
.....Slovakia, for its part, contended
that the changes identified by Hungary had not altered the nature
of the obligations under the Treaty from those originally undertaken,
so that no entitlement to terminate it arose from them.
Hungary further argued that termination of the Treaty was justified
by Czechoslovakia's material breaches of the Treaty, and in this
regard it invoked Article 60 of the Vienna Convention on the
Law of Treaties [on the effect of material breach]....
.....Hungary claimed in particular
that Czechoslovakia violated the 1977 Treaty by proceeding to
the construction and putting into operation of Variant C....
Hungary further maintained that Czechoslovakia had breached other
international conventions (among them the Convention of 31 May
1976 on the Regulation of Water Management Issues of Boundary
Waters) and general international law.
.....Slovakia denied that there
had been, on the part of Czechoslovakia or on its part, any material
breach of the obligations to protect water quality and nature,
and claimed that Variant C, far from being a breach, was devised
as "the best possible approximate application" of the
Treaty. It furthermore denied that Czechoslovakia had acted in
breach of other international conventions or general international
Finally, Hungary argued that subsequently imposed requirements
of international law in relation to the protection of the environment
precluded performance of the Treaty. The previously existing
obligation not to cause substantive damage to the territory of
another State had, Hungary claimed, evolved into an erga omnes
obligation [binding all nations] of prevention of damage pursuant
to the "precautionary principle". On this basis, Hungary
argued, its termination was "forced by the other party's
refusal to suspend work on Variant C".
.....Slovakia argued, in reply,
that none of the intervening developments in environmental law
gave rise to norms of jus cogens [a norm from which no
nation may deviate] that would override the Treaty. Further,
it contended that the claim by Hungary to be entitled to take
action could not in any event serve as legal justification for
termination of the Treaty under the law of treaties, but belonged
rather "to the language of self-help or reprisals".
The question ... deals with treaty law since the Court is asked
to determine what the legal effects are of the notification of
termination of the Treaty. The question is whether Hungary's
notification of 19 May 1992 brought the 1977 Treaty to an end,
or whether it did not meet the requirements of international
law, with the consequence that it did not terminate the Treaty.
The Court has referred earlier to the question of the applicability
to the present case of the Vienna Convention of 1969 on the Law
of Treaties. The Vienna Convention is not directly applicable
to the 1977 Treaty inasmuch as both States ratified that Convention
only after the [1977 bilateral] Treaty's conclusion. Consequently
only those rules which are declaratory of customary law are applicable
to the 1977 Treaty. As the Court has already stated above ...
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. On this, the Parties, too, were
broadly in agreement.
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
The Court will now turn to the first ground advanced by Hungary,
that of the state of necessity. In this respect, the Court will
merely observe that, even if a state of necessity is found to
exist, it is not a ground for the termination of a treaty. It
may only be invoked to exonerate from its responsibility a State
which has failed to implement a treaty. Even if found justified,
it does not terminate a Treaty; the Treaty may be ineffective
as long as the condition of necessity continues to exist; it
may in fact be dormant, but--unless the parties by mutual agreement
terminate the Treaty--it continues to exist. As soon as the state
of necessity ceases to exist, the duty to comply with treaty
Hungary also relied on the principle of the impossibility of
performance as reflected in Article 61 of the Vienna Convention
on the Law of Treaties. Hungary's interpretation of the wording
of Article 61 is, however, not in conformity with the terms of
that Article, nor with the intentions of the Diplomatic Conference
which adopted the Convention. Article 61, paragraph 1, requires
the "permanent disappearance or destruction of an object
indispensable for the execution" of the treaty to justify
the termination of a treaty on grounds of impossibility of performance.
During the 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.
Hungary contended that the essential object of the Treatyan
economic joint investment which was consistent with environmental
protection and which was operated by the two contracting parties
jointly--had permanently disappeared and that the Treaty had
thus become impossible to perform. 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 [such as Czechoslovakia's
subsequent implementation of Variant C] and ecological imperatives.
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 61, 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.
Hungary further argued that it was entitled to invoke a number
of events which, cumulatively, would have constituted a fundamental
change of circumstances. In this respect it specified 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 (see paragraph 95 above).
.....The prevailing political situation
was certainly relevant for the conclusion of the 1977 Treaty.
But the Court will recall that the Treaty provided for a joint
investment programme for the production of energy, the control
of floods and the improvement of navigation on the Danube. In
the Court's view, the prevalent political conditions were thus
not so closely linked to the object and purpose of the Treaty
that they constituted an essential basis of the consent of the
parties and, in changing, radically altered the extent of the
obligations still to be performed. The same holds good for the
economic system in force at the time of the conclusion of the
1977 Treaty. Besides, even though the estimated profitability
of the Project might have appeared less in 1992 than in 1977,
it does not appear from the record before the Court that it was
bound to diminish to such an extent that the treaty obligations
of the parties would have been radically transformed as a result.
.....The Court does not consider
that new developments in the state of environmental knowledge
and of environmental law can be said to have been completely
unforeseen. What is more, the formulation of Articles 15, 19
and 20, [of the 1977 treaty were] designed to accommodate change,
made it possible for the parties to take account of such developments
and to apply them when implementing those treaty provisions.
.....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. 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.
The Court will now examine Hungary's argument that it was entitled
to terminate the 1977 Treaty on the ground that Czechoslovakia
had violated its Articles 15, 19 and 20 (as well as a number
of other conventions and rules of general international law);
and that the planning, construction and putting into operation
of Variant C also amounted to a material breach of the
............................................................................ . .
Hungary contended that Czechoslovakia had violated Articles 15,
19 and 20 of the[ir] Treaty by refusing to enter into negotiations
with Hungary in order to adapt the Joint Contractual Plan to
new scientific and legal developments regarding the environment.
Articles 15, 19 and 20 oblige the parties jointly to take, on
a continuous basis, appropriate measures necessary for the protection
of water quality, of nature and of fishing interests.
.....Articles 15 and 19 expressly
provide that the obligations they contain shall be implemented
by the means specified in the Joint Contractual Plan. The failure
of the parties to agree on those means cannot, on the basis of
the record before the Court, be attributed solely to one party.
The Court has not found sufficient evidence to conclude that
Czechoslovakia had consistently refused to consult with Hungary
about the desirability or necessity of measures for the preservation
of the environment. The record rather shows that, while both
parties indicated, in principle, a willingness to undertake further
studies, in practice Czechoslovakia refused to countenance a
suspension of the works at Dunakiliti and, later, on Variant
C, while Hungary required suspension as a prior condition of
environmental investigation because it claimed continuation of
the work would prejudice the outcome of negotiations. In this
regard it cannot be left out of consideration that Hungary
itself, by suspending the works at Nagymaros and Dunakiliti,
contributed to the creation of a situation which was not conducive
to the conduct of fruitful negotiations [italics added].
Hungary's main argument for invoking a material breach of the
Treaty was the construction and putting into operation of Variant
C. . . . Czechoslovakia violated the Treaty only when it diverted
the waters of the Danube into the bypass canal in October 1992
[after Hungary's notification of termination]. In constructing
the works which would lead to the putting into operation of Variant
C, Czechoslovakia did not act unlawfully.
.....In the Court's view, therefore,
the notification of termination by Hungary on 19 May 1992 was
premature. No 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 it
when it did.
In this regard, it should be noted that, according to
Hungary's Declaration of 19 May 1992, the termination of the
1977 Treaty was to take effect as from 25 May 1992, that is only
six days later. 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. As the Court stated in
its Advisory Opinion on the Interpretation of the Agreement of
25 March 1951 between the WHO and Egypt (in which case the Vienna
Convention did not apply):
"Precisely what periods of time may be involved in the
observance of the duties to consult and negotiate, and what period
of notice of termination should be given, are matters which necessarily
vary according to the requirements of the particular case. In
principle, therefore, it is for the parties in each case to determine
the length of those periods by consultation and negotiation in
good faith." (I.C.J. Reports 1980, p. 96, para. 49.)
.....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.
Nor can the Court overlook that Czechoslovakia committed the
internationally wrongful act of putting into operation Variant
C as a result of Hungary's own prior wrongful conduct. As was
stated by the Permanent Court of International Justice:
"It is, moreover, a principle generally accepted in the
jurisprudence of international arbitration, as well as by municipal
courts, that one Party cannot avail himself of the fact that
the other has not fulfilled some obligation or has not had recourse
to some means of redress, if the former Party has, by some illegal
act, prevented the latter from fulfilling the obligation in question,
or from having recourse to the tribunal which would have been
open, to him." (Factory at Chorzów, Jurisdiction,
Judgment No. 8, 1927, P.C.I.J., Series A, No. 9, p. 31.)
.....Hungary, by its own conduct,
had prejudiced its right to terminate the Treaty; this would
still have been the case even if Czechoslovakia, by the time
of the purported termination, had violated a provision essential
to the accomplishment of the object or purpose of the Treaty.
Finally, the Court will address Hungary's claim that it was entitled
to terminate the 1977 Treaty because new requirements of international
law for the protection of the environment precluded performance
of the Treaty.
Neither of the Parties contended that new peremptory norms of
environmental law had emerged since the conclusion of the 1977
Treaty, and the Court will consequently not be required to examine
the scope of Article 64 of the Vienna Convention on the Law of
Treaties. On the other hand, the Court wishes to point out that
newly developed norms of environmental law [which will be covered
in the text, Ch.12] are relevant for the implementation of the
Treaty and that the parties could, by agreement, incorporate
them through the application of Articles 15, 19 and 20 of the
Treaty. These articles do not contain specific obligations of
performance but require the parties, in carrying out their obligations
to ensure that the quality of water in the Danube is not impaired
and that nature is protected, to take new environmental norms
into consideration when agreeing upon the means to be specified
in the Joint Contractual Plan.
.....By inserting these evolving
provisions in the Treaty, the parties recognized the potential
necessity to adapt the Project. Consequently, the[ir] Treaty
is not static, and is open to adapt to emerging norms of international
law. By means of Articles 15 and 19, new environmental norms
can be incorporated in the Joint Contractual Plan. The responsibility
to do this was a joint responsibility. The obligations contained
in Articles 15, 19 and 20 [of the 1977 treaty] are, by definition,
general and have to be transformed into specific obligations
of performance through a process of consultation and negotiation.
Their implementation thus requires a mutual willingness to discuss
in good faith actual and potential environmental risks. ...........................................................................
.....The awareness of the vulnerability
of the environment and the recognition that environmental risks
have to be assessed on a continuous basis have become much stronger
in the years since the Treaty's conclusion. These new concerns
have enhanced the relevance of Articles 15, 19 and 20.
The Court recognizes that both Parties agree on the need to take
environmental concerns seriously and to take the required precautionary
measures, but they fundamentally disagree on the consequences
this has for the joint Project. In such a case, third-party involvement
may be helpful and instrumental in finding a solution, provided
each of the Parties is flexible in its position.
Finally, Hungary maintained that by their conduct both parties
had repudiated the Treaty and that a bilateral treaty repudiated
by both parties cannot survive. The Court is of the view, however,
that although it has found that both Hungary and Czechoslovakia
failed to comply with their obligations under the 1977 Treaty,
this reciprocal wrongful conduct did not bring the Treaty to
an end nor justify its termination. The Court would set a precedent
with disturbing implications for treaty relations and the integrity
of the rule pacta sunt servanda if it were to conclude that a
treaty in force between States, which the parties have implemented
in considerable measure and at great cost over a period of years,
might be unilaterally set aside on grounds of reciprocal non-compliance.
It would be otherwise, of course, if the parties decided to terminate
the Treaty by mutual consent. But in this case, while Hungary
purported to terminate the Treaty, Czechoslovakia consistently
resisted this act and declared it to be without legal effect.
In the light of the conclusions it has reached above, the Court,
in reply to the question put to it ... finds that the notification
of termination by Hungary of 19 May 1992 did not have the legal
effect of terminating the 1977 Treaty and related instruments.