176

DISSENTING OPINION OF JUDGE HERCZEGH
[Translation]

I am most regretfully unable to share the position of the majority of
Members of the Court as expressed in this Judgment, and 1 find myself
obliged to draft a dissenting opinion to set out the facts and reasons
which explain the different conclusions I have reached.

The subject of the dispute between Hungary and Czechoslovakia, and
later Hungary and Slovakia, was the construction of a system of locks on
the Danube (hereinafter called “the G/N Project”) intended to enhance
“the broad utilization of the natural resources of the Bratislava-Budapest
section of the Danube . . .”. According to the Treaty concluded in Buda-
pest on 16 September 1977,

“the joint utilization of the Hungarian-Czechoslovak section of the

Danube will .. . significantly contribute to bringing about the social-

ist integration of the States members of the Council for Mutual Eco-

nomic Co-operation ...”.
The Project seemed in other respects likely to have a considerable impact
on the environment. The Court, called upon by the Parties to resolve the
dispute, was thus confronted with not only the implementation of the law
of treaties, but also the problems raised by protection of the environ-
ment, and with questions concerning the international responsibility of
States.

In its Advisory Opinion given to the General Assembly on 8 July 1996

on the Legality of the Threat or Use of Nuclear Weapons, the Court
declared that it recognized

“that the environment is not an abstraction but represents the living
space, the quality of life and the very health of human beings,
including generations unborn. The existence of the general obliga-
tion of States to ensure that activities within their jurisdiction and
control respect the environment of other States or of areas beyond
national control is now part of the corpus of international law relat-
ing to the environment.” (1. C.J. Reports 1996, pp. 241-242, para. 29.)

This Judgment of the Court cites that passage and stresses the impor-
tance of respecting the environment, but then does not take due account
of the application of that principle to the construction and operation of
the G/N Project.

The Court only grants a very modest place to ecological considerations

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in the “declaratory” part of its Judgment. As a judicial organ, the Court
was admittedly not empowered to decide scientific questions touching on
biology, hydrology, and so on, or questions of a technical type which
arose out of the G/N Project; but it could — and even should — have
ruled on the legal consequences of certain facts alleged by one Party and
either admitted or not addressed by the other, in order to assess their
respective conduct in this case.

Before determining the facts which could thus be pertinent, I must
make a few preliminary observations on the characteristics of the G/N
Project. The Project was an audacious scheme, in a class of its own and
the first to be designed as a system of locks for the exploitation in peak
mode of the hydroelectric resources of the Danube. The locks built on
the German and Austrian sections of the Danube do not operate in peak
mode; moreover, the dams on the Rhine operating in that mode are
much more modest works.

That mode of operation involved and involves risks which were not
altogether unknown to those responsible for drawing up the plans for the
G/N Project, but its designers reasoned within the confines of what was
known in the 1960s and 1970s — and that way of thinking is today con-
sidered outmoded, and rightly so. They accordingly minimized the risks,
whilst at the same time having an imperfect understanding of the damage
they could cause, and therefore of the possible solutions. To give just one
example, the fact that the Joint Contractual Plan only provided for a dis-
charge of 50 cubic metres per second in the old channel of the Danube
during the months of March to November shows clearly that the most
basic ecological considerations were not accorded the weight they
deserved. The original Project was criticized not only by the Hungarian
party, but also by the Czechoslovak leaders. Paragraph 38 of the Judg-
ment quotes the Czechoslovak President, Mr. Havel, as saying that the
G/N Project was a “totalitarian, gigomaniac monument which is against
nature” (Counter-Memorial of Hungary, Vol. 3, Ann. 88), together with
part of a statement made by the Czechoslovak Minister for the Environ-
ment, Mr. Vavrouÿek, for whom “the G/N Project was an old, obsolete
one”, and who went on to say that “there is no doubt that if we could
turn the course of time, we would never approve the original project . . .”
but that even though there were “many reasons to change, modify the
Treaty . .. it [was] not acceptable to cancel the Treaty . . . and negotiate
later on” (Memorial of Slovakia, Vol. IV, Ann. 97, pp. 248-249).

Given the declarations of the Czechoslovak leaders, it is somewhat
surprising that the Court adopted the approach that the ecological risks
listed by Hungary in 1989 were already known when the Treaty was con-
cluded but remained uncertain, and the provisions of Articles 15, 19 and
20 covered the protection of the natural environment, water quality, and

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so forth, whereas it could and should have concerned itself with the prob-
lems which the interpretation and implementation of these provisions
might raise in the field. However, the Judgment merely mentions the aims
of the Project and the advantages it was presumed to offer.

Unfortunately, that picture is a far cry from reality. It is difficult to see
otherwise why the Minister, Mr. VavrouSek, would have considered the
G/N Project contained in the 1977 Treaty to be “old”, of an “obsolete”
character, and needing to be “changed” or “modified”, and so on. More-
over, the key question is not whether the Treaty contained certain pro-
visions protecting the environment, but whether those provisions had
been effectively implemented during the construction of the G/N Project.

Since the negotiations which led to the conclusion of the 1977 Treaty,
ecological knowledge has become considerably broader and deeper whilst
international environmental law has also progressed. In its Advisory
Opinion on the Legal Consequences for States of the Continued Presence
of South Africa in Namibia (South West Africa) notwithstanding Secu-
rity Council Resolution 276 (1970), the Court found that:

“Moreover, an international instrument has to be interpreted and
applied within the framework of the entire legal system prevailing at
the time of the interpretation. In the domain to which the present
proceedings relate, the last fifty years . . . have brought important
developments . . . In this domain, as elsewhere, the corpus juris gen-
tium has been considerably enriched, and this the Court, if it is faith-
fully to discharge its functions, may not ignore.” (C.J. Reports
1971, pp. 31-32, para. 53.)

What held good for the Mandate system of the League of Nations also
holds good for the duty to safeguard the natural environment, the only
difference being that instead of a 50-year period, we have to look at a
20-year period in this case. Under Article 19 of the 1977 Treaty,

“The Contracting Parties shall, through the means specified in the
joint contractual plan, ensure compliance with the obligations for
the protection of nature arising in connection with the construction
and operation of the System of Locks.”

The original Hungarian wording uses, instead of the word “obliga-
tions”, the word “requirements”, but that does not in any way affect its
essential scope: the protection of nature was to be ensured in a manner
commensurate with the requirements of the day, that is to say, in 1989, in
accordance with the requirements of 1989, and not those that might have
prevailed in 1977. Likewise, and in so far as it is accepted, as it is by the
majority of the Members of the Court, that the Treaty still applies as it
stands, the same would hold good for 1997, and it is in accordance with

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 179

present-day requirements that the scope of the Parties’ treaty obligations
with regard to protection of the environment should be defined.
The Court, in the “prescriptive” part of its Judgment, states:

“Owing to new scientific insights and to a growing awareness of
the risks for mankind — for present and future generations — of
pursuit of such interventions at an unconsidered and unabated pace,
new norms and standards have been developed, set forth in a great
number of instruments during the last two decades. Such new norms
have to be taken into consideration, and such new standards given
proper weight, not only when States contemplate new activities but
also when continuing with activities begun in the past.” (Para. 140.)

It is regrettable that the Court did not follow this principle even in the
reasoning which led to its reply to the first question put to it in the
Special Agreement.

To have perceived the shortcomings of a project — to avoid using the
word “error” — and to recognize that one is the source of those short-
comings are two very different things which may sometimes be very far
apart. The principal argument put forward, in 1991, by the Czechoslovak
party in favour of the G/N Project, was based on the fact that the Project
was almost completed. By the acceleration of the works laid down in the
Protocol of 6 February 1989, certain Hungarian leaders wanted to do the
same thing —- to claim that a point of no return had been reached — in
order to deal with increasing opposition and resistance. Political changes
during that year prevented them from achieving that aim.

The crucial problem posed by the G/N Project was that of peak mode
operation, for which the 1977 Treaty makes no provision. Slovakia con-
firmed repeatedly that there was no agreement between the contracting
parties with regard to the peak mode operation of the system of locks. It
maintained that the operational rules relating to peak mode operation
had still not been established at the start of 1989, and that without the
agreement and co-operation of the parties no plan to operate in peak
mode could be implemented. In its Reply (Vol. II, pp. 8-9), Slovakia
states “the Gabëikovo plant would have operated at a level of maximum
peak mode operation that was never agreed between the Treaty parties”
and “Czechoslovakia offered its pledge to limit or exclude [that mode of
operation] in October 1989 if justified by subsequent studies” (emphasis
added). A few lines further on, it reaffirms that:

“no agreed method or level of peak mode operation had been
reached prior to 1989 . .. The focus on peak mode operation here is
therefore misplaced, for it assumes a mode of operation that was
neither agreed nor certain to be adopted in any form.” (/bid., p. 9.)

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 180

It is the Joint Contractual Plan which describes peak mode operation,
thus demonstrating that the 1977 Treaty and the Joint Contractual Plan
do not have the same legal character since Slovakia would not otherwise
have denied the existence of an agreement as to mode of operation.

It is true that the Preamble to the Special Agreement mentions the
Treaty on the Construction and Operation of the Gabtikovo-Nagymaros
Barrage System and related instruments (“the Treaty”) but, despite the
linking of the “related instruments” to the term freaty, it is absolutely
incorrect to conclude that all those instruments — including the Joint
Contractual Plan —— are of the same nature and carry the same legal
weight as the Treaty itself.

Moreover, the Special Agreement does not define the concept of
“related instruments” at all and a list of the instruments was not appended
to the Special Agreement or to the other documents lodged at the Court
by the Parties, for the simple reason that they disagreed as to the material
content of that expression. The references made by the Parties to the
“related instruments”, both in the written proceedings and in the hear-
ings, were vague, ambiguous and often contradictory. Since the file sub-
mitted to the Court was insufficient to clarify what was meant by that
expression, the Court should have avoided using it in its reasoning and
especially in the operative part. Unfortunately, it did not follow this
course, and this was detrimental to the necessary precision of its Judg-
ment.

To return to the problem posed by the mode of operation of the system
of locks, the above statements by the Slovak party show, moreover, that
Czechoslovakia itself had certain doubts and certain reservations about
the peak mode of operation. However, Slovakia emphasized during the
hearings that the Parties had to resolve the problem of defining “the
modalities of (and limitations to) the production of electricity in peak
mode” (CR 97/15, p. 50, Pellet), yet without specifying the treaty basis of
such a claim.

In any event there was an obvious contradiction between a project
designed for peak mode operation and the absence of an agreement
between the parties as to this mode of operation. The Court did not
attempt to resolve that contradiction, but was unable to remain entirely
silent as to the doubts it had regarding that mode of operation. In para-
graph 134 of the Judgment, the Court concluded that there had been an
“effective discarding by both Parties of peak power operation” (emphasis
added). In paragraph 138, it states that Czechoslovakia “was willing to
consider a limitation or even exclusion of operation” in peak power
mode.

Between 1977 and 1989 Hungarian experts became aware of the eco-
logical dangers potentially caused not only by the peak mode operation
of the system of locks, but also by the construction of certain works of
the system which had been designed with a view to such a mode of opera-
tion: more particularly the Nagymaros dam and the storage reservoir at

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 181

Dunakiliti as initially designed, that is, with an enormous surface area of
60 square kilometres, neither construction being indispensable or even of
use if the Gabéikovo power plant were to be operated in run-of-the-river
mode. Slovakia recognizes that the Nagymaros dam was intended, “first,
to compensate fluctuating water levels caused by peak operation of Gab-
&ikovo” (Memorial of Slovakia, para. 2.51), that “One of the functions of
the Nagymaros section was to utilize the Danube waters so as to permit
peak power production at Gabéikovo” (ibid., para. 7.13) or, to reiterate
the words used by the agent of Slovakia during the hearings, that “to
produce peak power electricity at Gabcikovo required the existence of
the Nagymaros weir” (CR 97/7, p. 15, Tomka).

It is therefore difficult to understand why Czechoslovakia insisted with
some vigour that Hungary had to continue with the construction of the
Nagymaros dam — when its primary purpose was to allow peak mode
operation of the Gabéikovo power station — if the mode of operation, as
Slovakia expressly concedes, was never the subject of an agreement
between the Parties. There was therefore no legal obstacle to prevent the
G/N Project from being modified for adaptation to a less dangerous
mode of operation. Slovakia, for its part, has repeatedly stated that

“The 1977 Treaty and the international agreements linked to it
were highly flexible . . . there were continuing studies of problems
emerging during construction, which led to modifications related,
inter alia, to the environment and water quality.” (CR 97/7, p. 14,
Tomka.)

In that case, the danger which the construction of the Nagymaros dam
posed for Budapest's drinking water supply — a point I shall return to
later — was a sufficient ground for amending the 1977 Treaty and
the international agreements linked to it, as Hungary suggested in its
Note Verbale dated 3 November 1989 (Memorial of Hungary, Vol. 4,
Ann. 29).

Before replying to the question “whether the Republic of Hungary was
entitled to suspend and subsequently abandon, in 1989, the works on the
Nagymaros Project and on the part of the Gabéikovo Project” for which
it was responsible, it should be noted that that question covers several
actions taken by the Hungarian Government which must be assessed
individually. Those actions are the following:

— in May 1989, the suspension of work on the Nagymaros dam;
— in July 1989, the suspension of work at Dunakiliti;
— in October 1989, the abandonment of work at Nagymaros.

At the same time, it should be noted that, towards the end of 1991,
Hungary carried on with and even completed the work relating to the

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downstream section of the bypass canal, on Czechoslovakian territory,
between Gabéikovo and Szap, for which it was responsible under Ar-
ticle 5, paragraph 5 (5) (4), of the 1977 Treaty, and that it did so because
it did not consider that part of the G/N Project to threaten the environ-
ment. That is symptomatic of its attitude towards the 1977 Treaty. The
allegation that Hungary repudiated or rejected the 1977 Treaty as such in
1989 or in 1990 is therefore groundless.

In order to justify its conduct, Hungary put forward various grounds
and these included, inter alia, a state of necessity, the main and decisive
reason. A state of necessity does not have the effect of extinguishing or
suspending a treaty, but it is a circumstance exonerating the State from
the responsibility it incurs in committing an act not in conformity with its
international obligations.

Article 33, paragraph 1, of the Draft of the International Law Com-
mission on the International Responsibility of States, considered as
expressing the rules of customary international law and cited by the
Court in its Judgment, stipulates the following:

“I. A state of necessity may not be invoked by a State as a
ground for precluding the wrongfulness of an act of that State not in
conformity with an international obligation of the State unless:

(a) the act was the only means of safeguarding an essential interest
of the State against a grave and imminent peril; and

(b) the act did not seriously impair an essential interest of the State
towards which the obligation existed.”

The state of necessity is “the situation of a State” — according to the
International Law Commission Report —

“whose sole means of safeguarding an essential interest threatened
by a grave and imminent peril is to adopt conduct not in conformity
with what is required of it by an international obligation to another
State” (Yearbook of the International Law Commission, 1980,
Vol. II, Part 2, p. 34, para. 1).

The “deliberate nature of the conduct, the intentional aspect of its failure
to conform with the international obligation” — according to the
Report —

“are not only undeniable but in some sense logically inherent in the
justification alleged; invoking a state of necessity implies perfect
awareness of having deliberately chosen to act in a manner not in
conformity with an international obligation” (ibid., p. 34, para. 3).

State of necessity is a very narrow concept in general international law.
In the course of the International Law Commission’s work on the codi-
fication of State responsibility, the great majority of its members were of
the view “that any possibility of the notion of state of necessity being

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applied where it is really dangerous must certainly be prevented, but
that this should not be so in cases where it is and will continue to be [a]
useful . . .” “The imperative need for compliance with the law must not
be allowed to result in situations so aptly characterized by the maxim
summum jus summa injuria” (Yearbook of the International Law Com-
mission, 1980, Vol. II, Part 2, p. 49, para. 31). Thus the International
Law Commission, expressing an almost general approach and convic-
tion, stressed that the situation had to involve an “essential” interest of
the State in question. That “essential” character naturally depends upon
the circumstances in which a State finds itself, which cannot be defined
beforehand, in the abstract. The peril threatening the essential interest
must be extremely grave and imminent, and it must have been avertable
only by means conflicting with an international obligation. In a state of
necessity, there is a

“grave danger to the existence of the State itself, to its political or
economic survival, the maintenance of conditions in which its essen-
tial services can function, the keeping of its internal peace, the sur-
vival of part of its population, the ecological preservation of all or
some of its territory...” (ibid., p. 35, para. 3).

Invoking a state of necessity is not a way to terminate treaty obliga-
tions lawfully, that is, to terminate an international treaty. However, the
party in question will be released from the consequences of the violation
of international law, since it acted in a state of necessity. The state of
necessity is a circumstance which exonerates from responsibility: in other
words, it exonerates the author of the unlawful act from that interna-
tional responsibility. Hence the problem has not been resolved — and
cannot be resolved — by the law of treaties, but pertains to the provi-
sions of the international law of State responsibility.

The question is therefore whether the criteria for a state of necessity
are fulfilled in relation to the construction of the Nagymaros dam? It
should be noted in this context that more than 500 bank-filtered wells
which satisfy about two-thirds of Budapest’s drinking water requirements
are situated on the island of Szentendre, downstream of Nagymaros. The
water from those wells is fit for consumption without any purification
procedure being necessary. The provision of drinking water for the Hun-
garian capital — which has two million inhabitants (that is, one-fifth of
the country’s population) —, qualitatively and quantitatively, certainly
constitutes an essential interest for Hungary. Hungary had to protect the
branches of the Danube, on either side of the island, against any erosion
endangering the production of drinking water from those wells.

The dredging of the bed of the Danube in the two branches around the
island of Szentendre — as laid down by Article 1, paragraph 3 (c), of the
1977 Treaty — had already caused serious damage. After the water
services of the Hungarian capital had raised the alarm, those works

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were not only suspended, but abandoned in 1980, resulting in a natural
improvement of the state of the river bed. Since the construction of
the Nagymaros dam would have had the same harmful effects down-
stream as those of the dredging, and in particular the erosion of the river
bed, that construction constituted a grave peril.

The expression “grave peril” refers to the existence of a strong like-
lihood that detrimental effects and very extensive damage will occur. It
is true that the damage in connection with Nagymaros would not occur
overnight, but after a lapse of time. The Judgment cites the International
Law Commission’s commentary to the effect that the “extremely grave
and imminent” peril] must “have been a threat to the interest at the actual
time”. That does not rule out, the Court adds,

“that a ‘peril’ appearing in the long term might be held to be ‘immi-
nent’ as soon as it is established, at the relevant point in time, that
the realization of that peril, however far off it might be, is not
thereby any less certain and inevitable” (para. 54).

Unfortunately, the Court has not drawn the obvious conclusion from
that definition as far as the construction of the Nagymaros dam is con-
cerned. There could be no doubt that the erosion of the bed of the Danube
downstream of Nagymaros would be the certain and inevitable conse-
quence of the dam. These were not “uncertainties”, as could be claimed in
relation to other ecological consequences of the G/N Project, but certainties
as to the foreseeable effects of the construction of the dam. If the Court did
not want, in this respect, to rely solely on Hungary’s arguments, it could
have used the information provided by Slovakia. According to Slovakia,

“the construction of water projects and hydropower plants upstream
in Germany and Austria had the effect of dramatically reducing the
quantities of sediments transported downstream to the Slovak-
Hungarian section .. . dredging coupled with erosion began to exceed
the annual deposition of sediment from upstream, the Danube river
bed started to deteriorate in the region between Devin Gate and Sap
(Palkoviéovo) and the erosion processes caused by ‘hungry water’
commenced.” (Memorial of Slovakia, para. 1.42.)

The Memorial of Slovakia cites the Report of 2 November 1993 of the
European Communities Working Group of Experts that:

“The main channel has been significantly lowered due to erosion
caused by a combination of several man-made factors:

— dam construction in Austria in the last decades resulting in a
sediment (in particular bed load) deficit . . .” (Jbid., para. 1.57.)

The Nagymaros dam could only have had the same effects, down-
stream, on the bed of the Danube, as the dams built in Austria had had

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 185

on the sector of the Slovak capital: the erosion of the river bed. As a
result of such erosion, the production of drinking water from the bank-
filtered wells on the banks of the island of Szentendre could only dimin-
ish, and the quality deteriorate. Certus an incertus quando. It was impos-
sible to predict exactly that that diminution would amount to such-and-
such a percentage of the former production of those wells, and whether it
would occur over five or ten years, but it was certain that the quantity of
water would diminish and its quality deteriorate in the relatively near
future.

The imminence of the peril in question depended on the construction
of the Nagymaros dam: without the dam, there would be no grave peril,
either imminent or long-term; once the dam had been constructed, it
would no longer have been appropriate to speak of a peril, but rather of
grave and permanent damage occurring for so long as the dam existed —
a dam built by the very State whose population and territory would have
been its victims. To claim that the suspension of works on the Nagy-
maros dam was not justified by a state of necessity, since the peril was not
imminent, means in reality that Hungary should have completed the dam
and waited for the bank-filtered wells on the island of Szentendre to dry
out because of the erosion of the river bed and for the supply of drinking
water to the Hungarian capital to be called critically into question. The
Court, in deciding the case, ought to have taken account of the damage
that would have occurred if the Party in question had not taken the
necessary preventive measures. States are under an obligation of preven-
tion and not merely of reparation.

Slovakia did not deny that the effectiveness of the wells would be
reduced, but it claimed that they would not be entirely lost and suggested
measures designed to deal with such a situation, but without taking
account of the cost of such measures (see Slovakia’s reply, dated 7 May
1997, to the question asked by the Vice-President (CR 97/15, p. 64).
Indeed, the surface waters could have been purified and rendered fit for
human consumption; however, that would have been enormously expen-
sive in view of the requirements of a city of two million inhabitants. The
other solution proposed, namely the discharging of large quantities
of gravel into the river bed, did not seem very realistic: both branches of
the Danube around the island of Szentendre, taken together, are
1,000 metres wide and 70 kilometres long. How much gravel would there-
fore have been necessary to counteract the erosion of the river bed caused
by the Nagymaros dam? The third solution raised, the construction of a
second dam downstream of Budapest, would have cost no less and, in the
end, a third dam would have been needed, at Paks or at Mohacs, not to
mention the potential consequences of such a series of dams on the
Yugoslav sector of the Danube. Jn theory, all three solutions were pos-
sible — the argument of impossibility does not stand up — but the imple-
mentation of these measures would have radically transformed the scope
of Hungary’s remaining obligations under the Treaty. Such a solution
denotes a fundamental change of circumstances which may be relied

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upon as a ground for terminating the Treaty, as prescribed in Article 62,
paragraph | (5), of the 1969 Vienna Convention on the Law of Treaties.
The Court expressed itself as follows in its Judgment of 2 February 1973
in the case concerning Fisheries Jurisdiction ( United Kingdom v. Iceland):

“International law admits that a fundamental change in the cir-
cumstances which determined the parties to accept a treaty, if it has
resulted in a radical transformation of the extent of the obligations
imposed by it, may, under certain conditions, afford the party
affected a ground for invoking the termination or suspension of the
treaty.” (LC.J. Reports 1973, p. 18, para. 36.)

Instead of taking into consideration the consequence of the changes
thus operated on the scope of Hungary’s remaining obligations under the
Treaty, the Court, in this Judgment, merely states that “the purification
of the river water, like the other measures envisaged, clearly would have
been a more costly technique” (para. 55). The costs of discharging gravel
into the river and those of constructing a second dam were not given
serious consideration, any more than was the radical transformation of
the scope of the obligations assumed.

As far as a fundamental change in circumstances is concerned, it
should be noted that he who can do the most can do the least. Hungary
did not rely on the Treaty having lapsed or on the suspension of the
Treaty as such, but it did suspend performance of one of its obligations
— the construction of the Nagymaros dam — on the basis of a state of
necessity, a ground for setting aside unlawfulness resulting from the fail-
ure to implement a treaty provision. In this case, it was a matter of safe-
guarding an essential interest against a peril which was grave and immi-
nent — that is, certain and inevitable. The taking of other measures to
counteract that grave peril would have radically transformed the scope of
the obligations to be performed by Hungary under the Treaty.

Since the Court has not adopted a position on the question whether
the suspension and abandonment of the construction at Nagymaros
impaired an essential interest of the other Party, I shall merely observe
that the Gabüikovo power plant operates normally today, as a run-of-
the-river power station, without a dam at Nagymaros, where the Danube
flows naturally in its bed. Boats use the bypass canal, so that navigation
has not been affected, and there is no danger of flooding which could
have been caused by the present state of the works. Accordingly, the sus-
pension and subsequent abandonment of the construction works has not
impaired an essential interest of the other contracting party.

However, the Court finds as follows:

“even if it had been established that there was, in 1989, a state of
necessity linked to the performance of the 1977 Treaty, Hungary
would not have been permitted to rely upon that state of necessity in

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order to justify its failure to comply with its treaty obligations, as it
had helped, by act or omission to bring it about” (para. 57).

That is a surprising conclusion, implying that Hungary should have
finished the construction of the Nagymaros dam, which in reality would
have helped to aggravate the state of necessity already existing as a result
of the start of the works, by causing irreparable damage to the drinking
water supply to its capital city. In that case, it would have had only itself
to blame, since it alone would have been the cause of the catastrophic
situation that would have ensued.

The suspension of the works at Dunakiliti is to be seen in a somewhat
different context. The suspension of those works was intended to safe-
guard an essential interest of Hungary, that is, principally the protection
of the aquifer situated below the Szigetkôz and the surrounding area. The
risk of damage to the aquifer arose from the size of the storage reservoir
at Dunakiliti (oversized were Gabëikovo to be operated as a run-of-the-
river power station) and from the polluting effect of its stagnant waters.
The national report of the Czech and Slovak Republic to the Rio Con-
ference showed that Gabéikovo constituted a threat to the environment:

“Example of disturbance of the unique water and rural ecological
systems due to large water works are the reservoirs in Nove Mlyny
in Czech Republic and the Gabéikovo water works on the Danube
river in the Slovak Republic. In the first example the mead forest
with its unique flora and fauna were seriously damaged, in the
second example, the huge and unique volume of underground water
is threatened and the systems of mead forests and river tributaries are
drastically affected.” (P. 92.) (See file of documents relating to the
second round of oral arguments of Hungary, 10-11 April 1997,
Ann. III-5.)

The suspension of the works at Dunakiliti certainly impaired the inter-
ests of Czechoslovakia inasmuch as they related to the commissioning of
the almost completed Gabéikovo power plant; the dykes which were
already constructed had to be protected, and a supply of water from the
Danube was essential in order to operate the plant even as a run-of-the-
river power station. There was therefore a conflict of interests between
the two States. Czechoslovakia could rely on the provisions of the Treaty
which the two Parties considered to be valid, whereas Hungary referred
to the ecological damage which would occur, as far as Dunakiliti —
unlike Nagymaros — was concerned, in the more distant future. How-
ever, the interests of Czechoslovakia were of a financial nature, theoreti-
cally easy to compensate, whereas those of Hungary related to the safe-
guarding of its ecological balance and the difficult and uncertain struggle
against damage to its environment. Jn dubio pro natura.

The G/N Project had other consequences for the environment, the
details of which were discussed at length by the Parties, which presented

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 188

them in diametrically opposed ways. That detailed and conflicting pres-
entation did not ease the Court’s task and made it harder for it to deter-
mine the facts not denied or challenged by one or the other of the Parties.

The Court held that the state of necessity, as a ground for precluding
the wrongfulness of an act not in conformity with an international obli-
gation, can only be accepted on an exceptional basis and, referring to the
relevant International Law Commission Report, added that

“the state of necessity can only be invoked under certain strictly
defined conditions which must be cumulatively satisfied; and the
State concerned is not the sole judge of whether those conditions
have been met” (para. 51).

I entirely concur with that approach, but I cannot accept the conclu-
sions drawn in this case by the Court. It has concluded that, with respect
to both Nagymaros and Gabtikovo,

“the perils invoked by Hungary, without prejudging their possible
gravity, were not sufficiently established in 1989, nor were they
‘imminent’; and... Hungary had available to it at that time means
of responding to these perceived perils other than the suspension and
abandonment of works with which it had been entrusted” (para. 57).

This is absolutely not the case. As far as Hungary was concerned, what
was at stake was the safeguarding of an essential interest against a peril
which was grave and imminent, that is to say certain and inevitable, and
any measures taken to counteract that peril would have radically trans-
formed the scope of the obligations to be performed under the Treaty. By
suspending and abandoning the works at Nagymaros, Hungary has not
impaired an essential interest of Czechoslovakia, and it is precisely by
constructing the dam at Nagymaros that it would have contributed to
an unequalled state of necessity and to a situation catastrophic for its
capital. The existence of the peril alleged by Hungary was recognized —
at least in part — by the other Party, and Hungary therefore did not act
in an arbitrary manner.

The first question asked in the Special Agreement was whether the
Republic of Hungary was entitled to suspend certain works for which it
was responsible under the 1977 Treaty. The Vienna Convention on the
Law of Treaties is silent as to the state of necessity. However, interna-
tional law — and particularly the law of responsibility —- recognizes it.
The state of necessity exists not only in theory, but also in reality. In the
present case, even the strictest criteria applied cumulatively prove that, as
far as the construction of the Nagymaros dam is concerned, Hungary
was entitled to rely on that ground precluding its responsibility for not
having fulfilled one of its obligations under the 1977 Treaty. It was there-
fore entitled to suspend and subsequently abandon the works at Nagy-
maros. As far as the suspension of the works at Dunakiliti is concerned,
the existence of a state of necessity is debatable, but Hungary’s anxieties

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 189

regarding the ecological risks occasioned by the reservoir — and partially
recognized by Czechoslovakia itself — should not have been taken lightly,
and still less categorically refuted. That latter measure of suspension was
undoubtedly provisional (the installations at Dunakiliti have been main-
tained in good condition by Hungary up to the present day). Although
the circumstances prevailing on that site do not entirely relieve Hungary
of its responsibility, they do nonetheless provide some mitigation which
the Court should have taken into account.

The Court, whilst refusing to accept that Hungary was entitled to sus-
pend and subsequently abandon, in 1989, the works on the G/N Project
relating to Nagymaros, recognizes — albeit indirectly — that Hungary's
position is well founded, when it manages to assert, in the “prescriptive”
part of its Judgment, that the Nagymaros dam should not be built: “with
the effective discarding by both Parties of peak power operation, there is
no longer any point in building it” (para. 134); “the construction of the
Nagymaros dam would have become pointless” (para. 138). Moreover, it
must be acknowledged that the ecological considerations that now weigh
against the dam are the same as those holding in 1989. If it has finally
been concluded that the dam should not have been built in 1997, this is
because in reality it should not have been built in 1989, either.

The dispute between the two Parties is very much the result of their
geographical situations. The harmonization of the interests of the coun-
tries upstream and downstream is the crucial problem of the law govern-
ing international watercourses. During the work done by the United
Nations on the Draft Convention on the Law of the Non-Navigational
Uses of International Watercourses, the upstream countries complained
that the provisions of the draft limited their right to use and develop the
resources of those watercourses, whereas the downstream countries criti-
cized the provisions of the draft by maintaining that they failed to protect
their interests adequately and even allowed significant damage to be
inflicted upon them. As far as the course of the Danube is concerned,
Slovakia is an upstream country and Hungary a downstream country. In
this Judgment the Court should have maintained a balance, admittedly
hard to achieve, between the interests of the upstream and the down-
stream countries, and have ensured that harmonious progress in enhance-
ment of the natural resources would be carefully organized to prevent the
long-term disadvantages from outweighing the immediate advantages.
Unfortunately, in the present case, it has not succeeded in doing so.

I have found it necessary to stress this question since the position to be
taken, in particular, on whether Hungary was entitled to suspend and
subsequently abandon the works at Nagymaros, and to suspend those at
Dunakiliti, to a large extent determines the replies, or at least the reason-
ing, for the questions which follow.

x *

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 190

I now come to the second question asked in the Special Agreement,
that is, “whether the Czech and Slovak Federal Republic was entitled to
proceed, in November 1991, to the provisional solution and to put into
operation from October 1992 this system . . .”.

Since Slovakia has consistently maintained that the 1977 Treaty was
extremely flexible and essentially open-ended, the contracting parties
were entitled to propose that it be adapted to the requirements of envi-
ronmental protection — having regard to new information and experi-
ence gained — and even modified, in order that the Treaty might match
those requirements. The abandonment of the construction of the Nagy-
maros dam, whose main function would have been to allow the use of the
Gabtikovo power plant in peak mode (a use for which there had been no
prior agreement between the parties), has not called in question the
accomplishment of the object and purpose of the Treaty.

In September 1991, Mr. Vavrouëek, the Czech Minister for the Envi-
ronment, declared to the Hungarian Parliament:

“I believe there is the only practicable way, a traditional one, that
is being used not only in case of international treaties, but also when
new acts are adopted. It simply means to prepare a new treaty and to
incorporate into the last paragraph provisions that would cancel
obsolete parts of the 1977 Treaty.” (Memorial of Slovakia, Vol. IV,
Ann. 97, p. 249.)

In other words, that would have involved the conclusion of a treaty
taking the place of the old one, by modifying or abrogating those provi-
sions that are out of date.

Between Mr. Vavrouëek’s visit to Budapest and the recourse to the
“provisional solution” in November 1991, only two months elapsed.
That is an extremely brief interval when one considers that the 1977
Treaty took two decades to prepare.

The Report of the Special Rapporteur on the Law on the Non-Navi-
gational Uses of International Watercourses noted the importance of the
parties’ duty to negotiate by citing the Judgment delivered by the Court
in the North Sea Continental Shelf cases. That obligation flows from the
very nature of the respective rights of the parties. It

“merely constitutes a special application of a principle which under-
lies all international relations, and which is moreover recognized in
Article 33 of the Charter of the United Nations...” (4 CJ. Reports
1969, p. 47, para. 86).

From all these considerations, the Rapporteur concludes:

“there is a general principle of international law that requires nego-
tiations among States in dealing with international fresh water
resources . . . Jand they also have the obligation] to negotiate the
apportionment of the waters of an international watercourse” ( Year-

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 191

book of the International Law Commission, 1980, Vol. IT, Part. 2,
pp. 116-117, paras. 31 and 34).

The Articles of the Draft Convention on the Law of the Non-Naviga-
tional Uses of International Waterways, adopted very recently by the
General Assembly of the United Nations, are prompted by exactly the
same principles.

The Court, in its Judgment (para. 141), reaffirms what it stated in the
North Sea Continental Shelf cases:

“[the Parties] are under an obligation so to conduct themselves that
the negotiations are meaningful, which will not be the case when
either of them insists upon its own position without contemplating
any modification of it” (4. C.J. Reports 1969, p. 47, para. 85).

{t is difficult to accept that during the two months in question, the con-
tracting parties to the 1977 Treaty exhausted all the possibilities of reach-
ing an agreement with respect to a mutually acceptable modification of
that instrument. However, the Czechoslovak Government decided to
change unilaterally the state of affairs established in the Treaty and
openly to breach it. Under the cover of a “provisional” measure, it
undertook works which related to a permanent construction and were
not authorized by the Treaty, thereby making it impossible to attain its
object and purpose. Instead of negotiating in order to reach an agree-
ment, it opted for a policy of “faits accomplis”, having recourse to uni-
lateral measures when the negotiations were still under way. The oppor-
tunity of a solution agreed between the Parties nonetheless still existed.

The Parties do not agree as to when and how the decision was taken.
On 31 August 1989 the Czechoslovak Prime Minister, Mr. Adamec,
raised the possibility of “unilateral measures” to ensure the operation of
the GabCikovo dam. In its representation of 30 October 1989, Czecho-
slovakia indicated that:

“In the event that the Republic of Hungary fail to fulfil its obli-
gations the Czechoslovakian party would be obliged to implement a

provisional technical solution . . . consisting in diverting, for the
Gabtikovo works, the volumes of Danube water agreed in the origi-
nal treaty...”

In a work by Egil Lejon, copies of which were made available to Mem-
bers of the Court during the Slovak stage of the site visit, the following is
stated:

“January 17, 1991: Based on the report, the Slovak Govern-
ment decides to start preparations of the temporary solution, i.e.
‘Variant C’, not depending on Hungarian co-operation, however not
excluding the possibility of returning to the Treaty conditions
in the future.” (Gabéikovo-Nagymaros, Old and New Sins, 1994
(English ed., 1996), p. 86.)

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 192

Furthermore, Bratislava newspapers reported that work had actually
started on 2 April 1991.

Those various dates are only pertinent in the event that it has to be
decided whether the parties negotiated in good faith. However, the Court
was not called upon to pronounce on the Parties’ responsibility for the
failure of the negotiations. In any event, it does not appear to be neces-
sary to proceed with an examination of the different dates relevant to the
recourse to the “provisional solution” — namely Variant C — since the
important one is that appearing in the Special Agreement.

Variant C differs in several respects from the original Project included
in the 1977 Treaty. Its Phase I includes nine features unrelated to the
1977 Project, and Phase IT has three. Instead of the dam at Dunakiliti
and its installations, another dam and its additional installations were
built, 10 kilometres upstream, in Czechoslovak territory, making it pos-
sible to divert waters from the Danube into the bypass canal leading to
Gabéikovo. The storage reservoir at Cunovo has 30 per cent less surface
area as compared with the original Dunakiliti project, which has cer-
tainly reduced the risks of damage that polluted water retained by its
dykes could have caused to the groundwater. However, at the same time,
Variant C has enabled the Danube to be diverted from its old bed, over
a 40-kilometre section instead of the 30 provided for in the original
Project, and this has had a significant impact on the environment of the
Szigetkôz region.

It is not, however, the range of new installations that puts Variant C
quite at odds with the original Project and renders it contrary to the 1977
Treaty and to general international law, but the fact that its construction
is the result of acts undertaken unilaterally by Czechoslovakia, without
the agreement of the directly interested party, Hungary. Variant C was
built despite repeated protests from Hungary and the fact that its opera-
tion was going to have direct and significant consequences on the terri-
tory of Hungary.

Slovakia claims that Hungary acquiesced in the original plan to divert
the Danube, and that it was therefore not entitled to protest against the
diversion carried out under Variant C. It is true that, under the 1977
Treaty and the related Joint Contractual Plan, the Parties were to build
the Dunakiliti reservoir and divert the Danube waters into the bypass
canal leading to Gabéikovo, and from there to Szap. However, that part
of the original Project did not deprive Hungary of control over its border
waters and did not expose the ecology of one of its regions to the effects
of uncontrollable activity by its neighbour. On the basis of the original
Project, Hungary was able to defend its own interests directly, and Vari-
ant C deprived it of that possibility. Hungary no longer commanded the
means made available to it by Article 14, paragraph 1, of the 1977 Treaty
in respect of its ability to withdraw water from the Danube in excess of
the specified quantities, in order to protect its essential interests regarding
the environment of the Szigetkôz. Only Slovakia is in a position to with-

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 193

draw water from the Danube at its own convenience. The old project,
with all its drawbacks and defects, was a joint enterprise under the joint
control of both parties. Variant C no longer had or has anything in com-
mon between the two parties, as a result of the exclusive control exercised
by Czechoslovakia — now Slovakia — and was never given any kind of
approval by Hungary.

According to the well-known maxim sic utere tuo ut alienum non lae-
das, one’s property may not be used in such a way as to cause significant
damage to another. Furthermore, in the present case, Czechoslovakia did
not, and Slovakia today does not use its property in an unlawful manner,
but it has appropriated — and this is one of the key factors in the dispute
—- something which did not belong to it, namely almost all the waters of
the Danube. It follows from Article 3 of the 1976 Agreement on Bound-
ary Waters that the Parties to the dispute “are entitled, unless otherwise
agreed, to one-half of the natural discharge of water not augmented by
technical means”. The Parties have not agreed otherwise, since there has
been no agreement between them as to Variant C. Variant C is therefore
a grave breach both of the 1977 Treaty and of the 1976 Treaty on Bound-
ary Waters.

In its Judgment the Court has rejected the doctrine of “approximate
application” on which Slovakia based its reasoning in order to justify the
construction of Variant C. I concur with the conclusion and reasoning of
the Court on that point: “In spite of having a certain external physical
similarity with the original Project, Variant C thus differed sharply from
it in its legal characteristics.” (Para. 77.)

Thus, I shall not labour the point. | am moreover in agreement with
what the Court states in its Judgment as regards the justification of
Variant C as a countermeasure:

“an important consideration is that the effects of a countermeasure
must be commensurate with the injury suffered, taking account of
the rights in question.

The Court considers that Czechoslovakia, by unilaterally assum-
ing control of a shared resource, and thereby depriving Hungary of
its right to an equitable and reasonable share of the natural resources
of the Danube — with the continuing effects of the diversion of
these waters on the ecology of the riparian area of the Szigetkôz —
failed to respect the proportionality which is required by interna-
tional law.

the diversion of the Danube carried out by Czechoslovakia was
not a lawful countermeasure because it was not proportionate”
(paras. 85 and 87).

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 194

That observation, however, implies a need for certain additional con-
clusions. We are not dealing simply with “intersecting wrongs” on the
part of both Parties to the dispute. The Court has not taken care to dis-
tinguish between the “wrongs”, and has declared, inter alia, “that both
Hungary and Czechoslovakia failed to comply with their obligations
under the 1977 Treaty”. It referred to the existence of “reciprocal wrong-
ful conduct” and “reciprocal non-compliance” (para. 114) as the conse-
quence of “the fact that the Treaty has not been fully implemented by
either party for years” (para. 133). What should have been done was
assess how serious the unlawful conduct attributed to both Parties was in
order to make the necessary inferences.

Hungary, by abandoning the construction of the Nagymaros dam,
ruled out the peak mode operation of the Gabüikovo power plant, a
mode of operation on which there was no prior agreement between the
Parties, and, by suspending the works at Dunakiliti, it delayed the com-
missioning of the Gab¢éikovo power plant. As a result, it inflicted finan-
cial losses on its partner whereas Czechoslovakia, later Slovakia, by
building on its territory a dam unilaterally diverting the waters of the
Danube, violated a provision essential to the accomplishment of the
object and purpose of the Treaty, as laid down in Article 60, paragraph 3,
of the Vienna Convention on the Law of Treaties.

The construction of Variant C infringed several essential provisions of
the 1977 Treaty: not only those to be found in Articles 15, 19 and 20, but
above all those concerning the joint use and control of the plant built
under the Treaty. The Agent of Slovakia admitted this expressly during
the hearings: “a joint operation was of the very essence of the Project
under the 1977 Treaty” (CR97/7, p. 16, Tomka). Variant C therefore
infringed the object and purpose of the 1977 Treaty itself, and that
serious infringement is tantamount to a rejection of the Treaty by
Czechoslovakia.

The Court, in its Advisory Opinion on the Legal Consequences for
States of the Continued Presence of South Africa in Namibia (South
West Africa) notwithstanding Security Council Resolution 276 (1970),
referred to General Assembly resolution 2145 (XXI), when stating:

“The resolution in question is therefore to be viewed as the exer-
cise of the right to terminate a relationship in case of a deliberate
and persistent violation of obligations which destroys the very object
and purpose of that relationship.” (4 CJ. Reports 1971, p. 47,
para. 95.)

The object and purpose of the 1977 Treaty (the “socialist integration”
of the States Members of COMECON, included in its preamble, having
in the event become obsolete) consisted in joint utilization of the natural
resources of the Danube. The unilateral diversion of these waters and
their exclusive utilization by Slovakia were undoubtedly a breach of a
provision essential to the accomplishment of the object and purpose of

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 195

the Treaty, whereas the conduct of Hungary simply delayed but did not
preclude the commissioning of the power plant; Hungary did not destroy
“the object and purpose” of the treaty relationship.

I disagree with the Judgment of the Court when it concludes that
Czechoslovakia was entitled, in November 1991, to carry out Variant C
(para. 88), given that:

“between November 1991 and October 1992, Czechoslovakia con-
fined itself to the execution, on its own territory, of the works which
were necessary for the implementation of Variant C, but which
could have been abandoned if an agreement had been reached
between the parties and did not therefore predetermine the final
decision to be taken” (para. 79) .

I cannot agree with that explanation for the following reasons:

The fact that the work on Variant C was only carried out on Czecho-
slovak territory does not preclude its unlawfulness. A State can quite well
use its own territory to breach its international obligations, and there are
numerous examples which could show this to be the case. The fact that
the works “could have been halted” is not a convincing argument either
and, in any event, work on Variant C was not stopped, as requested by
Hungary — not even for a limited time.

The constructions of Variant C could not be considered to be “works
preparatory” to the diverting of the Danube waters. Only the design and
plans for Variant C may be so described, but not the actual recourse to
that Variant. namely the construction of works — dykes, dams —
intended for the diversion. The Judgment refers (in paragraph 79), to
the commentary of the International Law Commission on the Draft
Articles on State Responsibility. However, that commentary expressly
mentions the following:

“With regard to the timing of any claim for cessation on the part
of the injured State or States, it is obvious that no such claim could
be lawfully put forward unless the wrongful conduct had begun,
namely unless the threshold of unlawfulness had been crossed by an
allegedly wrongdoing State’s conduct.” ( Yearbook of the Interna-
tional Law Commission, 1993, Vol. II, Part 2, p. 57, para. 14;
emphasis added.)

Since Variant C, as such, constituted a breach of the 1977 Treaty, the
unlawful conduct of Czechoslovakia began when it proceeded to the con-
struction of those works necessary for the unilateral diversion of the
Danube waters. It is completely arbitrary and inconsistent to separate
that conduct of Czechoslovakia — unlawful in my opinion — from its
result — unlawful according to the Court.

Accordingly, I conclude that Czechoslovakia acted unlawfully when,
in November 1991, it embarked on the provisional solution. In other

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 196

words, it was no more entitled to do so than to commission it in October
1992.

x * s

I feel obliged to express a dissenting opinion in respect of the reply to
the third question put to the Court, namely: “what are the legal effects of
the notification, on 19 May 1992, of the termination of the Treaty by the
Republic of Hungary?” In other words, did the 1977 Treaty remain in
force?

On 19 May 1992, the Government of Hungary notified the Govern-
ment of Czechoslovakia that it would consider the 1977 Treaty to have
been terminated as from 25 May of that same year. Diplomatic exchanges
show that it was Czechoslovakia’s categoric refusal to suspend the work
on Variant C, even for a limited time, which determined the date of the
Government of Hungary’s decision to terminate the Treaty. The main
reason for that decision was a wish to respond to the rejection of the
Treaty by Czechoslovakia, constituted by the construction of Variant C.
Article 60 of the Vienna Convention on the Law of Treaties authorizes a
contracting party to act in this way, as will be shown later.

The Hungarian Government took its decision on the basis of the fol-
lowing considerations: (a) state of necessity; (b) impossibility of per-
formance; (c) fundamental change of circumstances; (d) substantial
breach of the Treaty by the other party; and, finally, (e) protection of
the environment which had become mandatory in international law.

As a preliminary, I would observe that in reality one does not often see
“pure” or unequivocal cases, in the sense that they require only one single
abstract type of legal settlement or solution. More often than not, the
legal situation in which the parties find themselves falls within the ambit
of several rules of international law at the same time.

I shall not examine all the arguments put forward by Hungary. Its
main argument to justify termination of the 1977 Treaty is clearly that
the construction of Variant C constituted a breach of that Treaty, for
the reasons given before the Court. Hungary described the grave breach
constituted by Variant C as a “repudiation” by Czechoslovakia of the
Treaty, constituting a fundamental change of circumstances (CR 97/13,
p. 42, Crawford). The aforementioned concepts and expressions reflect
the situation which prevailed in May 1992, viewed from different angles.
Hungary further contended that that situation could be characterized as
a case of impossibility of performance and, of course, that the develop-
ment of international environmental law ought to be taken into consid-
eration in this context.

From among these different approaches, I shall select the one which
seems to me to be the most adequate and the result of which best reflects
the legal points characterizing the situation. That will render superfluous

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 197

the examination of the other arguments put forward, which I do not think
do more than “reorganize” those points differently and less precisely.

Article 60, paragraph 1, of the Vienna Convention on the Law of
Treaties provides:

“A material breach of a bilateral treaty by one of the parties
entitles the other to invoke the breach as a ground for terminating
the treaty or suspending its operation in whole or in part.”

Article 60, paragraph 3, provides as follows:

“A material breach of a treaty, for the purposes of this article,
consists in:

(a) a repudiation of the treaty not sanctioned by the present Con-
vention; or

(b) the violation of a provision essential to the accomplishment of
the object or purpose of the treaty.”

Variant C constituted a violation of the provisions of the 1977 Treaty
and other rules of international law, since Hungary was deprived of the
Danube waters which belonged to it. As joint operation was the very
essence of the Project provided for by the Treaty, the unilateral diversion
precluded the accomplishment of the object and purpose of the Treaty.
Notwithstanding the ecological effects that the diversion of the Danube is
alleged to have had, predictably, on Hungary, the mere fact of a uni-
lateral diversion — taken on its own — was so serious that it justified
termination of the Treaty. The main and decisive reason for the termina-
tion is to be found in the construction of Variant C and its unlawfulness,
which must be described as a fundamental violation within the meaning
of Article 60, paragraph 3 (b), of the Vienna Convention. The question
falls clearly within the ambit of the law of treaties. All the other reasons
put forward are merely subsidiary.

If Variant C truly constituted a grave breach, a fundamental violation
of the Treaty — which the Court itself has noted — Hungary was entitled
to terminate the Treaty.

Was Hungary’s decision premature?

It is true that the diversion of the waters of the Danube had not yet
been completed in May 1992, but the grave breach of the Treaty had
already begun — as I have shown earlier — when Czechoslovakia started
constructing Variant C in November of the preceding year. It is difficult
to accept that Hungary should have passively awaited completion of the
construction of Variant C. Czechoslovakia had on several occasions
stated that it was determined to implement the “provisional” solution.
The bilateral negotiations were deadlocked; work on Variant C was pro-
gressing well and Czechoslovakia made no secret of its intention to carry
out a unilateral diversion of the Danube waters at Cunovo on the
planned date, while refusing, even for a strictly limited time, to suspend
the works whose objective was no longer a mystery.

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 198

When implementing Variant C, Czechoslovakia always described it, in so
far as it was a measure designed to attain the purpose of the 1977 Treaty, as
an “approximate application” of that Treaty. In an attempt to stop con-
struction work, Hungary sought to deprive Variant C of its alleged justifi-
cation, and hence it announced its termination of the Treaty. Work on
Variant C was undertaken and completed on Czechoslovak territory alone.
Termination of the 1977 Treaty was the only means available to Hungary
to prevent Czechoslovakia from diverting the Danube waters in the sector
where both banks of the river belong to that country. On 19 May 1992, it
notified Czechoslovakia that it would consider the Treaty to be terminated
as from 25 May of that year. The period of notice was certainly very short
but Article 65, paragraph 2, of the Vienna Convention on the Law of Trea-
ties, which provides for a three month time-limit, contains — as it should be
emphasized — the following exception: “except in cases of special urgency”.
In such a case the time-limit may be less than three months. In May 1992,
in the face of very visible progress in the building of Variant C, Hungary
was manifestly in such a situation “of special urgency”.

Recourse to termination of the 1977 Treaty proved ineffectual: Czecho-
slovakia’s decision was taken, and it was to remain irreversible. In fact,
construction had started up and work was not suspended for a single
moment; it carried on, even after Hungary had notified its partner that it
considered the Treaty to be terminated. In any event, the unilateral diver-
sion of the Danube was completed on 26 October 1992, and the grave
breach of the 1977 Treaty was complete. Even if Hungary’s Note of
19 May could — as the Court holds — have been considered premature,
it took effect, at the latest, when the diversion of the Danube waters was
completed.

Did Hungary, as a result of the alleged violations of its international
obligations, forfeit its right to terminate the 1977 Treaty?

In the first part of my dissenting opinion, [ showed that, when sus-
pending and then abandoning the works at Nagymaros, Hungary acted
out of a state of necessity, for which the criteria — which do not need to
be repeated here — were all met. The state of necessity exonerated Hun-
gary from the responsibility incurred on account of its failure to comply
with certain provisions of the 1977 Treaty. As far as the suspension of the
works at Dunakiliti is concerned, the majority of the criteria for a state of
necessity were also met, but it is true that Czechoslovakia had an essen-
tial interest in the continuation of these works. Hungary, for its part,
completed the construction of the dykes downstream of Gabëikovo for
which it was responsible under the Treaty and it offered to compensate
Czechoslovakia for such losses as that State might have sustained. There
are therefore, in Hungary’s favour, circumstances exonerating it from
responsibility and certain mitigating circumstances, since the conduct for
which it can be reproached is not as serious as that constituted by

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Czechoslovakia’s construction of Variant C. The Treaty did not survive
the joint effect of the serious breach constituted by the diversion of the
Danube and Hungary’s notification of its termination. The question of
State succession to the Treaty is therefore irrelevant.

As far as the expression “related instruments” is concerned, it should
be noted that with the disappearance of the Treaty, the fundamental text
which could hold all the instruments together no longer exists. That
expression subsequently lost any legal significance. That does not mean
that all the instruments whose provisions could have a certain relation-
ship to those of the 1977 Treaty have become obsolete. Their fate should
be decided separately, having regard to the relevant rules of international
law.

%
* *

The Court in its Judgment has taken the view, however, that the
16 September 1977 Treaty remained in force and that the Slovak Repub-
lic, as successor State to the Federal Czech and Slovak Republic,
became a party to the Treaty as from 1 January 1993. With regard to the
legal consequences of the Judgment, including the rights and obligations
for the Parties which the Court was asked to determine under Article 2,
paragraph 2, of the Special Agreement, the Court, in paragraph 2 of the
operative part of the Judgment, states at point B that

“Hungary and Slovakia must . . . take all necessary measures to
ensure the achievement of the objectives of the Treaty of 16 Septem-
ber 1977, in accordance with such modalities as they may agree
upon”.

For its part, point C of paragraph 2 of the operative part uses the words
“in accordance with the Treaty”, and point E the expression “in accord-
ance with the relevant provisions of the Treaty”.

By deciding that the 1977 Treaty is still in force, the Court made its
own task more difficult and did nothing to ease that of the Parties since
they have to reach an agreement on the resolution of questions over
which they have been in dispute. According to its reasoning,

“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 . .. might be
unilaterally set aside on grounds of reciprocal non-compliance.”
(Para. 114.)

1 must observe that the expression “reciprocal non-compliance” does
not adequately reflect the cause or causes of the termination of the treaty.
However, that is not my essential objection regarding that part of the
Judgment; rather am I concerned at the divergences — not to say con-
tradictions — between its “declaratory” part and its “prescriptive” part.
The Court, while maintaining the Treaty in force, wanted to avoid being

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set against the maxim summum jus summa injuria, and it recognized that
the 1977 Treaty, in its original form, did not apply. I will cite the perti-
nent passages of the Judgment in extenso:

“133. The Court, however, cannot disregard the fact that the
Treaty has not been fully implemented by either party for years, and
indeed that their acts of commission and omission have contributed
to creating the factual situation that now exists. Nor can it overlook
that factual situation — or the practical possibilities and impossibili-
ties to which it gives rise — when deciding on the legal requirements
for the future conduct of the Parties.

What is essential, therefore, is that the factual situation as it has
developed since 1989 shall be placed within the context of the pre-
served and developing treaty relationship, in order to achieve its
object and purpose in so far as that is feasible. For it is only then
that the irregular state of affairs which exists as the result of the fail-
ure of both Parties to comply with their treaty obligations can be
remedied.

134. What might have been a correct application of the law in
1989 or 1992, if the case had been before the Court then, could be a
miscarriage of justice if prescribed in 1997. The Court cannot ignore
the fact that the Gabtikovo power plant has been in operation for
nearly five years, that the bypass canal which feeds the plant receives
its water from a significantly smaller reservoir formed by a dam
which is built not at Dunakiliti but at Cunovo, and that the plant is
operated in a run-of-the-river mode and not in peak hour mode as
originally foreseen. Equally, the Court cannot ignore the fact that,
not only has Nagymaros not been built, but that, with the effective
discarding by both Parties of peak power operation, there is no
longer any point in building it.”

The reasoning of the Court in that context is based above all on the
role of the time factor — the eight years that have elapsed between 1989
and 1997: “What might have been a correct application of the law in
1989 or 1992, if the case had been before the Court then, could be a mis-
carriage of justice if prescribed in 1997.” (One should not forget, in this
context, that Hungary proposed, as early as November 1989, that the dis-
putes which the parties could not resolve themselves should be decided by
arbitration or by recourse to the International Court of Justice.) In my
opinion, however, the approach limiting the impact of the time factor to
the period that has elapsed since the dispute arose does not enable the
Court, against the background of a complex case, to incorporate all of its
relevant aspects.

Time passed, not only between 1989 and 1997, but also between 1977

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 201

and 1989. The 1977 Treaty — a bilateral treaty — was concluded in a
specific political context, that of the bid to promote socialist integration
of the States Members of the Council for Mutual Economic Assistance,
which was radically transformed in 1989. The economic climate prevail-
ing in 1977, marked by the economic system known as the command
economy, was overturned in a no less radical manner when the advent of
the market economy modified all expectations as to the cost and viability
of the G/N Project. Furthermore, since the signature of the Treaty, eco-
logical knowledge and requirements have evolved rapidly. The Parties
both admitted that the Treaty was out of date: Hungary by proposing to
amend it in November 1989; and Czechoslovakia in September 1991, by
recognizing that the obsolete parts of the Treaty should be cancelled
(Memorial of Slovakia, Vol. IV, Ann. 97, p. 249). The sudden recourse to
Variant C, the so-called “provisional solution”, prevented the Parties
from finding a mutually acceptable solution to the problems raised by the
Treaty. The facts, which I need not repeat at this juncture, that argue for
modification of the Treaty and require the conclusion of a new agreement
already existed in 1989, and do not derive from the period subsequent to
that date as consequences of the unlawful conduct of the Parties.

The Judgment of the Court puts those Parties back in the context of an
“old”, “out-of-date” Treaty, whilst prescribing sensible, reasonable and
even essential changes: to exclude definitively the peak mode operation
of the Gabtikovo power plant; not to build the Nagymaros works since
“there is no longer any point in building [them]”; and, with regard to
environmental protection, to take “new norms” into consideration and to
assess “new requirements” appropriately, “not only when States contem-
plate new activities but also when continuing with activities begun in the
past” (para. 140).

Those norms would be more effective and the Parties to the dispute
could apply them more easily without the references to the 1977 Treaty.
The Court could and should have founded the prescriptive part of its
Judgment not upon an obsolete Treaty which could not be implemented
— and which in my opinion had been terminated — but on the uncon-
tested rules of general international law and on other treaties and con-
ventions in force between the Parties, in order to resolve the problems
they had inherited from the old G/N Project.

One may be certain that the termination of the 1977 Treaty would not
have left the Parties to the dispute in a legal vacuum. Their “relation-
ship”, as the Court noted,

“is also determined by the rules of other relevant conventions to which
the two States are party, by the rules of general international law and,
in this particular case, by the rules of State responsibility” (para. 132).

The preamble to the Special Agreement concluded by Slovakia and Hun-
gary states that the Slovak Republic is the “sole successor State” of the

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GABCIKOVO-NAGYMAROS PROJECT (DISS. OP. HERCZEGH) 202

Czech and Slovak Federal Republic “in respect of rights and obligations
relating to the Gabëikovo-Nagymaros Project”. The rights and obliga-
tions created by the performance of the 1977 Treaty before it was termi-
nated are not affected by the termination of the Treaty. Under Article 70,
paragraph 1, of the Vienna Convention on the Law of Treaties:

“Unless the treaty otherwise provides or the parties otherwise
agree, the termination of a treaty under its provisions or in accord-
ance 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.” (Emphasis added.)

The installations constructed in good faith in fulfilment of the 1977
Treaty — such as Gabtikovo and Dunakiliti — are not affected by the
ultimate fate of that Treaty. Slovakia may therefore keep up and use the
Gabéikovo power plant in a manner not causing significant damage to its
neighbour, that is to say, in particular, by operating it in run-of-the-river
mode. As to the problems resulting from construction of the Cunovo
dam and the diversion of the Danube waters, they should be settled in
accordance with other treaties in force between the Parties, in particular
the 1976 Boundary Waters Convention, and with the other principles and
rules of international law in force between the Parties and placing them
under certain binding obligations. It follows that each of the Parties is
obliged to refrain from any act or any conduct having harmful effects on
the environment and causing significant damage to the other Party.

The most important point in that regard is the equitable and reason-
able sharing of the Danube waters. The Judgment of the Court cites
Article 5, paragraph 2, of the Convention on the Law of the Non-
Navigational Uses of International Watercourses, according to which:

“Watercourse States shall participate in the use, development and
protection of an international watercourse in an equitable and
reasonable manner. Such participation includes both the right to
utilize the watercourse and the duty to co-operate in the protection
and development thereof, as provided in the present Convention.”
(Para. 147.)

That principle, which may rightly be deemed to express a general rule
of international law in force, is relevant to the settlement of the dispute in
this case. The unlawfulness of Variant C lay in the appropriation by
Czechoslovakia, then by Slovakia, of almost all the Danube waters,
a shared natural resource. That unilateral use must cease as soon as
possible and definitively. That aim can be achieved by “associating
Hungary, on an equal footing, in the operation and management, and the

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GABCIKOVO-NAGYMAROS PROJECT (DISS, OP. HERCZEGH) 203

benefits” of the works built to date in fulfilment of the 1977 Treaty or
outside and against it, and that by way of the agreed utilization of
the natural resources of the Danube in the sector in question. This
would provide a remedy for the breach of international law constituted
by Variant C, and the de facto status would be transformed into a régime
of law. That is the direction and spirit expressed by the Court in para-
graph 146 of it its Judgment. I concur with the essence of the message
contained in that paragraph, whilst considering myself obliged to
express it differently in order to take account of the reasons which I
have attempted to set out above.

Finally, I reiterate my conclusion that the 1977 Treaty was lawfully ter-
minated and that it is no longer in force. The prescriptive part of the
Judgment of the Court would, in my opinion, have been more logical and
more convincing if the Court had not based it on the 1977 Treaty but
rather on the rules of general international law and on the other treaties
and conventions binding on the Parties.

These considerations forced me to vote against points A, B and D of
paragraph 1 of the operative part.

As regards the points of paragraph 2 of the operative part, it goes with-
out saying that, having voted against point D of the first paragraph,
I had to vote against point A of the second paragraph. I am firmly con-
vinced that Hungary and Slovakia must negotiate in good faith, on the
basis of the international law in force, to implement the rights and obli-
gations relating to the shared natural resources of the Danube. These
shared resources should be exploited jointly and in accordance with
mutually agreed arrangements. However, the fact that point B of para-
graph 2 refers expressly to the objectives of the Treaty of 16 September
1977, point C to a joint operational régime in accordance with that
Treaty, and point E to the relevant provisions of the said Treaty — which
Treaty in my opinion, and having regard to the arguments put forward
above, is no longer in force — prevented me from voting in favour of
these points. At the same time, I voted in favour of point D on the
reciprocal compensation of Slovakia and Hungary — unless the Parties
otherwise agree — for the damage they have sustained on account
of the construction of the System of Locks, since I considered that point
to be fair and in accordance with the relevant rules of international law.

(Signed) Géza HERCZEGH.

200