International Court of Justice

YEAR 1997

1997
25 September
General List
No. 92

25 September 1997

CASE CONCERNING THE GABCÍKOVO-NAGYMAROS PROJECT

(HUNGARY/SLOVAKIA)

Treaty of 16 September 1977 concerning the construction and operation of the Gabcíkovo-Nagymaros System of Locks — "Related instruments".

Suspension and abandonment by Hungary, in 1989, of works on the Project — Applicability of the Vienna Convention of 1969 on the Law of Treaties — Law of treaties and law of State responsibility — State of necessity as a ground for precluding the wrongfulness of an act — "Essential interest" of the State committing the act — Environment — "Grave and imminent peril" — Act having to constitute the "only means" of safeguarding the interest threatened — State having "contributed to the occurrence of the state of necessity".

Czechoslovakia,s proceeding, in November 1991, to "Variant C" and putting into operation, from October 1992, this Variant — Arguments drawn from a proposed principle of approximate application — Respect for the limits of the Treaty — Right to an equitable and reasonable share of the resources of an international watercourse — Commission of a wrongful act and prior conduct of a preparatory character — Obligation to mitigate damages — Principle concerning only the calculation of damages — Countermeasures — Response to an internationally wrongful act — Proportionality — Assumption of unilateral control of a shared resource.

Notification by Hungary, on 19 May 1992, of the termination of the 1977 Treaty and related instruments — Legal effects — Matter falling within the law of treaties — Articles 60 to 62 of the Vienna Convention on the Law of Treaties — Customary law — Impossibility of performance — Permanent disappearance or destruction of an "object" indispensable for execution — Impossibility of performance resulting from the breach, by the party invoking it, of an obligation under the Treaty — Fundamental change of circumstances — Essential basis of the consent of the parties — Extent of obligations still to be performed — Stability of treaty relations — Material breach of the Treaty — Date on which the breach occurred and date of notification of termination — Victim of a breach having itself committed a prior breach of the Treaty — Emergence of new norms of environmental law — Sustainable development — Treaty provisions permitting the parties, by mutual consent, to take account of those norms — Repudiation of the Treaty — Reciprocal non-compliance — Integrity of the rule pacta sunt servanda — Treaty remaining in force until terminated by mutual consent.

Legal consequences of the Judgment of the Court — Dissolution of Czechoslovakia — Article 12 of the Vienna Convention of 1978 on Succession of States in respect of Treaties — Customary law — Succession of States without effect on a treaty creating rights and obligations "attaching" to the territory — Irregular state of affairs as a result of failure of both Parties to comply with their treaty obligations — Ex injuria jus non oritur — Objectives of the Treaty — Obligations overtaken by events — Positions adopted by the parties after conclusion of the Treaty — Good faith negotiations — Effects of the Project on the environment — Agreed solution to be found by the Parties — Joint régime — Reparation for acts committed by both Parties — Co-operation in the use of shared water resources — Damages — Succession in respect of rights and obligations relating to the Project — Intersecting wrongs — Settlement of accounts for the construction of the works.

JUDGMENT

Present: President SCHWEBEL; Vice-President WEERAMANTRY; Judges ODA, BEDJAOUI, GUILLAUME, RANJEVA, HERCZEGH, SHI, FLEISCHHAUER, KOROMA, VERESHCHETIN, PARRA-ARANGUREN, KOOIJMANS, REZEK; Judge ad hoc SKUBISZEWSKI; Registrar VALENCIA-OSPINA.

In the case concerning the Gabcíkovo-Nagymaros Project,

between

the Republic of Hungary,

represented by

H. E. Mr. György Szénási, Ambassador, Head of the International Law Department, Ministry of Foreign Affairs,

as Agent and Counsel;

H. E. Mr. Dénes Tomaj, Ambassador of the Republic of Hungary to the Netherlands,

as Co-Agent;

Mr. James Crawford, Whewell Professor of International Law, University of Cambridge,

Mr. Pierre-Marie Dupuy, Professor at the University Panthéon-Assas (Paris II) and Director of the Institut des hautes études internationales of Paris,

Mr. Alexandre Kiss, Director of Research, Centre national de la recherche scientifique (ret.),

Mr. László Valki, Professor of International Law, Eötvös Loránd University, Budapest,

Mr. Boldizsár Nagy, Associate Professor of International Law, Eötvös Loránd University, Budapest,

Mr. Philippe Sands, Reader in International Law, University of London, School of Oriental and African Studies, and Global Professor of Law, New York University,

Ms Katherine Gorove, consulting Attorney,

as Counsel and Advocates;

Dr. Howard Wheater, Professor of Hydrology, Imperial College, London,

Dr. Gábor Vida, Professor of Biology, Eötvös Loránd University, Budapest, Member of the Hungarian Academy of Sciences,

Dr. Roland Carbiener, Professor emeritus of the University of Strasbourg,

Dr. Klaus Kern, consulting Engineer, Karlsruhe,

as Advocates;

Mr. Edward Helgeson,

Mr. Stuart Oldham,

Mr. Péter Molnár

as Advisers;

Dr. György Kovács,

Mr. Timothy Walsh,

Mr. Zoltán Kovács

as Technical Advisers;

Dr. Attila Nyikos,

as Assistant;

Mr. Axel Gosseries, LL.M.,

as Translator;

Ms Éva Kocsis,

Ms Katinka Tompa,

as Secretaries,

and

the Slovak Republic,

represented by

H. E. Dr. Peter Tomka, Ambassador, Legal Adviser of the Ministry of Foreign Affairs,

as Agent;

Dr. Václav Mikulka, Member of the International Law Commission,

as Co-Agent, Counsel and Advocate;

Mr. Derek W. Bowett, C.B.E., Q.C., F.B.A., Whewell Professor emeritus of International Law at the University of Cambridge, Former Member of the International Law Commission,

as Counsel;

Mr. Stephen C. McCaffrey, Professor of International Law at the University of the Pacific, McGeorge School of Law, Sacramento, United States of America, Former Member of the International Law Commission,

Mr. Alain Pellet, Professor at the University of Paris X-Nanterre and at the Institute of Political Studies, Paris, Member of the International Law Commission,

Mr. Walter D. Sohier, Member of the Bar of the State of New York and of the District of Columbia,

Sir Arthur Watts, K.C.M.G., Q.C., Barrister, Member of the Bar of England and Wales,

Mr. Samuel S. Wordsworth, avocat à la Cour d,appel de Paris, Solicitor of the Supreme Court of England and Wales, Frere Cholmeley, Paris,

as Counsel and Advocates;

Mr. Igor Mucha, Professor of Hydrogeology and Former Head of the Groundwater Department at the Faculty of Natural Sciences of Comenius University in Bratislava,

Mr. Karra Venkateswara Rao, Director of Water Resources Engineering, Department of Civil Engineering, City University, London,

Mr. Jens Christian Refsgaard, Head of Research and Development, Danish Hydraulic Institute,

as Counsel and Experts;

Dr. Cecília Kandráèová, Director of Department, Ministry of Foreign Affairs,

Mr. Ludìk Krajhanzl, Attorney at Law, Vyroubal Krajhanzl Skácel and Partners, Prague,

Mr. Miroslav Liška, Head of the Division for Public Relations and Expertise, Water Resources Development State Enterprise, Bratislava,

Dr. Peter Vršanský, Minister-Counsellor, Chargé d,affaires a.i., of the Embassy of the Slovak Republic, The Hague,

as Counsellors;

Miss Anouche Beaudouin, allocataire de recherche at the University of Paris X-Nanterre,

Ms Cheryl Dunn, Frere Cholmeley, Paris,

Ms Nikoleta Glindová, attachée, Ministry of Foreign Affairs,

Mr. Drahoslav Štefánek, attaché, Ministry of Foreign Affairs,

as Legal Assistants,

THE COURT

composed as above,

after deliberation,

delivers the following Judgment:

1. By a letter dated 2 July 1993, filed in the Registry of the Court on the same day, the Ambassador of the Republic of Hungary (hereinafter called "Hungary") to the Netherlands and the Chargé d,affaires ad interim of the Slovak Republic (hereinafter called "Slovakia") to the Netherlands jointly notified to the Court a Special Agreement in English that had been signed at Brussels on 7 April 1993 and had entered into force on 28 June 1993, on the date of the exchange of instruments of ratification.

2. The text of the Special Agreement reads as follows:

" The Republic of Hungary and the Slovak Republic,

Considering that differences have arisen between the Czech and Slovak Federal Republic and the Republic of Hungary regarding the implementation and the termination of the Treaty on the Construction and Operation of the Gabcíkovo-Nagymaros Barrage System signed in Budapest on 16 September 1977 and related instruments (hereinafter referred to as "the Treaty"), and on the construction and operation of the "provisional solution";

Bearing in mind that the Slovak Republic is one of the two successor States of the Czech and Slovak Federal Republic and the sole successor State in respect of rights and obligations relating to the Gabcíkovo-Nagymaros Project;

Recognizing that the Parties concerned have been unable to settle these differences by negotiations;

Having in mind that both the Czechoslovak and Hungarian delegations expressed their commitment to submit the differences connected with the Gabcíkovo-Nagymaros Project in all its aspects to binding international arbitration or to the International Court of Justice;

Desiring that these differences should be settled by the International Court of Justice;

Recalling their commitment to apply, pending the Judgment of the International Court of Justice, such a temporary water management régime of the Danube as shall be agreed between the Parties;

Desiring further to define the issues to be submitted to the International Court of Justice,

Have agreed as follows:

Article 1

The Parties submit the questions contained in Article 2 to the International Court of Justice pursuant to Article 40, paragraph 1, of the Statute of the Court.

Article 2

(1) The Court is requested to decide on the basis of the Treaty and rules and principles of general international law, as well as such other treaties as the Court may find applicable,

(a)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 Gabcíkovo Project for which the Treaty attributed responsibility to the Republic of Hungary;

(b)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, described in the Report of the Working Group of Independent Experts of the Commission of the European Communities, the Republic of Hungary and the Czech and Slovak Federal Republic dated 23 November 1992 (damming up of the Danube at river kilometre 1851.7 on Czechoslovak territory and resulting consequences on water and navigation course);

(c)what are the legal effects of the notification, on 19 May 1992, of the termination of the Treaty by the Republic of Hungary.

(2) The Court is also requested to determine the legal consequences, including the rights and obligations for the Parties, arising from its Judgment on the questions in paragraph 1 of this Article.

Article 3

(1) All questions of procedure and evidence shall be regulated in accordance with the provisions of the Statute and the Rules of Court.

(2) However, the Parties request the Court to order that the written proceedings should consist of:

(a)a Memorial presented by each of the Parties not later than ten months after the date of notification of this Special Agreement to the Registrar of the International Court of Justice;

(b)a Counter-Memorial presented by each of the Parties not later than seven months after the date on which each has received the certified copy of the Memorial of the other Party;

(c)a Reply presented by each of the Parties within such time-limits as the Court may order.

(d)The Court may request additional written pleadings by the Parties if it so determines.

(3) The above-mentioned parts of the written proceedings and their annexes presented to the Registrar will not be transmitted to the other Party until the Registrar has received the corresponding part of the proceedings from the said Party.

Article 4

(1) The Parties agree that, pending the final Judgment of the Court, they will establish and implement a temporary water management régime for the Danube.

(2) They further agree that, in the period before such a régime is established or implemented, if either Party believes its rights are endangered by the conduct of the other, it may request immediate consultation and reference, if necessary, to experts, including the Commission of the European Communities, with a view to protecting those rights; and that protection shall not be sought through a request to the Court under Article 41 of the Statute.

(3) This commitment is accepted by both Parties as fundamental to the conclusion and continuing validity of the Special Agreement.

Article 5

(1) The Parties shall accept the Judgment of the Court as final and binding upon them and shall execute it in its entirety and in good faith.

(2) Immediately after the transmission of the Judgment the Parties shall enter into negotiations on the modalities for its execution.

(3) If they are unable to reach agreement within six months, either Party may request the Court to render an additional Judgment to determine the modalities for executing its Judgment.

Article 6

(1) The present Special Agreement shall be subject to ratification.

(2) The instruments of ratification shall be exchanged as soon as possible in Brussels.

(3) The present Special Agreement shall enter into force on the date of exchange of instruments of ratification. Thereafter it will be notified jointly to the Registrar of the Court.

In witness whereof the undersigned being duly authorized thereto, have signed the present Special Agreement and have affixed thereto their seals."

3. Pursuant to Article 40, paragraph 3, of the Statute and Article 42 of the Rules of Court, copies of the notification and of the Special Agreement were transmitted by the Registrar to the Secretary-General of the United Nations, Members of the United Nations and other States entitled to appear before the Court.

4. Since the Court included upon the Bench no judge of Slovak nationality, Slovakia exercised its right under Article 31, paragraph 2, of the Statute to choose a judge ad hoc to sit in the case: it chose Mr. Krzysztof Jan Skubiszewski.

5. By an Order dated 14 July 1993, the Court fixed 2 May 1994 as the time-limit for the filing by each of the Parties of a Memorial and 5 December 1994 for the filing by each of the Parties of a Counter-Memorial, having regard to the provisions of Article 3, paragraph 2 (a) and (b), of the Special Agreement. Those pleadings were duly filed within the prescribed time-limits.

6. By an Order dated 20 December 1994, the President of the Court, having heard the Agents of the Parties, fixed 20 June 1995 as the time-limit for the filing of the Replies, having regard to the provisions of Article 3, paragraph 2 (c), of the Special Agreement. The Replies were duly filed within the time-limit thus prescribed and, as the Court had not asked for the submission of additional pleadings, the case was then ready for hearing.

7. By letters dated 27 January 1997, the Agent of Slovakia, referring to the provisions of Article 56, paragraph 1, of the Rules of Court, expressed his Government,s wish to produce two new documents; by a letter dated 10 February 1997, the Agent of Hungary declared that his Government objected to their production. On 26 February 1997, after having duly ascertained the views of the two Parties, the Court decided, in accordance with Article 56, paragraph 2, of the Rules of Court, to authorize the production of those documents under certain conditions of which the Parties were advised. Within the time-limit fixed by the Court to that end, Hungary submitted comments on one of those documents under paragraph 3 of that same Article. The Court authorized Slovakia to comment in turn upon those observations, as it had expressed a wish to do so; its comments were received within the time-limit prescribed for that purpose.

8. Moreover, each of the Parties asked to be allowed to show a video cassette in the course of the oral proceedings. The Court agreed to those requests, provided that the cassettes in question were exchanged in advance between the Parties, through the intermediary of the Registry. That exchange was effected accordingly.

9. In accordance with Article 53, paragraph 2, of the Rules of Court, the Court decided, after having ascertained the views of the Parties, that copies of the pleadings and documents annexed would be made available to the public as from the opening of the oral proceedings.

10. By a letter dated 16 June 1995, the Agent of Slovakia invited the Court to visit the locality to which the case relates and there to exercise its functions with regard to the obtaining of evidence, in accordance with Article 66 of the Rules of Court. For his part, the Agent of Hungary indicated, by a letter dated 28 June 1995, that, if the Court should decide that a visit of that kind would be useful, his Government would be pleased to co-operate in organizing it. By a letter dated 14 November 1995, the Agents of the Parties jointly notified to the Court the text of a Protocol of Agreement, concluded in Budapest and New York the same day, with a view to proposing to the Court the arrangements that might be made for such a visit in situ; and, by a letter dated 3 February 1997, they jointly notified to it the text of Agreed Minutes drawn up in Budapest and New York the same day, which supplemented the Protocol of Agreement of 14 November 1995. By an Order dated 5 February 1997, the Court decided to accept the invitation to exercise its functions with regard to the obtaining of evidence at a place to which the case relates and, to that end, to adopt the arrangements proposed by the Parties. The Court visited the area from 1 to 4 April 1997; it visited a number of locations along the Danube and took note of the technical explanations given by the representatives who had been designated for the purpose by the Parties.

11. The Court held a first round of ten public hearings from 3 to 7 March and from 24 to 27 March 1997, and a second round of four public hearings on 10, 11, 14 and 15 April 1997, after having made the visit in situ referred to in the previous paragraph. During those hearings, the Court heard the oral arguments and replies of:

For Hungary: H. E. Mr. Szénási,

Professor Valki,

Professor Kiss,

Professor Vida,

Professor Carbiener,

Professor Crawford,

Professor Nagy,

Dr. Kern,

Professor Wheater,

Ms Gorove,

Professor Dupuy,

Professor Sands.

For Slovakia: H. E. Dr. Tomka,

Dr. Mikulka,

Mr. Wordsworth,

Professor McCaffrey,

Professor Mucha,

Professor Pellet,

Mr. Refsgaard,

Sir Arthur Watts.

12. The Parties replied orally and in writing to various questions put by Members of the Court. Referring to the provisions of Article 72 of the Rules of Court, each of the Parties submitted to the Court its comments upon the replies given by the other Party to some of those questions.

*

13. In the course of the written proceedings, the following submissions were presented by the Parties:

On behalf of Hungary,

in the Memorial, the Counter-Memorial and the Reply ( mutatis mutandis identical texts):

"On the basis of the evidence and legal argument presented in the Memorial, Counter-Memorial and this Reply, the Republic of Hungary

Requests the Court to adjudge and declare

First, that the Republic of Hungary was entitled to suspend and subsequently abandon the works on the Nagymaros Project and on the part of the Gabcíkovo Project for which the Treaty attributed responsibility to the Republic of Hungary;

Second, that the Czech and Slovak Federal Republic was not entitled to proceed to the ,provisional solution, (damming up of the Danube at river kilometres 1,851.7 on Czechoslovak territory and resulting consequences on water and navigation course);

Third, that by its Declaration of 19 May 1992, Hungary validly terminated the Treaty on the Construction and Operation of the Gabcíkovo-Nagymaros Barrage System of 16 September 1977;

Requests the Court to adjudge and declare further

that the legal consequences of these findings and of the evidence and the arguments presented to the Court are as follows:

(1)that the Treaty of 16 September 1977 has never been in force between the Republic of Hungary and the Slovak Republic;

(2)that the Slovak Republic bears responsibility to the Republic of Hungary for maintaining in operation the ,provisional solution, referred to above;

(3)that the Slovak Republic is internationally responsible for the damage and loss suffered by the Republic of Hungary and by its nationals as a result of the ,provisional solution,;

(4)that the Slovak Republic is under an obligation to make reparation in respect of such damage and loss, the amount of such reparation, if it cannot be agreed by the Parties within six months of the date of the Judgment of the Court, to be determined by the Court;

(5)that the Slovak Republic is under the following obligations:

(a)to return the waters of the Danube to their course along the international frontier between the Republic of Hungary and the Slovak Republic, that is to say the main navigable channel as defined by applicable treaties;

(b)to restore the Danube to the situation it was in prior to the putting into effect of the provisional solution; and

(c)to provide appropriate guarantees against the repetition of the damage and loss suffered by the Republic of Hungary and by its nationals."

On behalf of Slovakia:

in the Memorial, the Counter-Memorial and the Reply ( mutatis mutandis identical texts):

"On the basis of the evidence and legal arguments presented in the Slovak Memorial, Counter-Memorial and in this Reply, and reserving the right to supplement or amend its claims in the light of further written pleadings, the Slovak Republic

Requests the Court to adjudge and declare:

1.That the Treaty between Czechoslovakia and Hungary of 16 September 1977 concerning the construction and operation of the Gabcíkovo/Nagymaros System of Locks, and related instruments, and to which the Slovak Republic is the acknowledged successor, is a treaty in force and has been so from the date of its conclusion; and that the notification of termination by the Republic of Hungary on 19 May 1992 was without legal effect.

2.That the Republic of Hungary was not entitled to suspend and subsequently abandon the works on the Nagymaros Project and on that part of the Gabcíkovo Project for which the 1977 Treaty attributed responsibility to the Republic of Hungary.

3.That the act of proceeding with and putting into operation Variant C, the ,provisional solution,, was lawful.

4.That the Republic of Hungary must therefore cease forthwith all conduct which impedes the full and bona fide implementation of the 1977 Treaty and must take all necessary steps to fulfil its own obligations under the Treaty without further delay in order to restore compliance with the Treaty.

5.That, in consequence of its breaches of the 1977 Treaty, the Republic of Hungary is liable to pay, and the Slovak Republic is entitled to receive, full compensation for the loss and damage caused to the Slovak Republic by those breaches, plus interest and loss of profits, in the amounts to be determined by the Court in a subsequent phase of the proceedings in this case."

14. In the oral proceedings, the following submissions were presented by the Parties

On behalf of Hungary,

at the hearing of 11 April 1997:

The submissions read at the hearing were mutatis mutandis identical to those presented by Hungary during the written proceedings.

On behalf of Slovakia:

at the hearing of 15 April 1997:

"On the basis of the evidence and legal arguments presented in its written and oral pleadings, the Slovak Republic,

Requests the Court to adjudge and declare:

1.That the Treaty, as defined in the first paragraph of the Preamble to the Compromis between the Parties, dated 7 April 1993, concerning the construction and operation of the Gabcíkovo/Nagymaros System of Locks and related instruments, concluded between Hungary and Czechoslovakia and with regard to which the Slovak Republic is the successor State, has never ceased to be in force and so remains, and that the notification of 19 May 1992 of purported termination of the Treaty by the Republic of Hungary was without legal effect;

2.That the Republic of Hungary was not entitled to suspend and subsequently abandon the works on the Nagymaros Project and on that part of the Gabcíkovo Project for which the 1977 Treaty attributes responsibility to the Republic of Hungary;

3.That the Czech and Slovak Federal Republic was entitled, in November 1991, to proceed with the ,provisional solution, and to put this system into operation from October 1992; and that the Slovak Republic was, and remains, entitled to continue the operation of this system;

4.That the Republic of Hungary shall therefore cease forthwith all conduct which impedes the bona fide implementation of the 1977 Treaty and shall take all necessary steps to fulfil its own obligations under the Treaty without further delay in order to restore compliance with the Treaty, subject to any amendments which may be agreed between the Parties;

5.That the Republic of Hungary shall give appropriate guarantees that it will not impede the performance of the Treaty, and the continued operation of the system;

6.That, in consequence of its breaches of the 1977 Treaty, the Republic of Hungary shall, in addition to immediately resuming performance of its Treaty obligations, pay to the Slovak Republic full compensation for the loss and damage, including loss of profits, caused by those breaches together with interest thereon;

7.That the Parties shall immediately begin negotiations with a view, in particular, to adopting a new timetable and appropriate measures for the implementation of the Treaty by both Parties, and to fixing the amount of compensation due by the Republic of Hungary to the Slovak Republic; and that, if the Parties are unable to reach an agreement within six months, either one of them may request the Court to render an additional Judgment to determine the modalities for executing its Judgment."

*

* *

15. 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.

16. The Danube is the second longest river in Europe, flowing along or across the borders of nine countries in its 2,860-kilometre course from the Black Forest eastwards to the Black Sea. For 142 kilometres, it forms the boundary between Slovakia and Hungary. The sector with which this case is concerned is a stretch of approximately 200 kilometres, between Bratislava in Slovakia and Budapest in Hungary. Below Bratislava, the river gradient decreases markedly, creating an alluvial plain of gravel and sand sediment. This plain is delimited to the north-east, in Slovak territory, by the Malý Danube and to the south-west, in Hungarian territory, by the Mosoni Danube. The boundary between the two States is constituted, in the major part of that region, by the main channel of the river. The area lying between the Malý Danube and that channel, in Slovak territory, constitutes the itný Ostrov; the area between the main channel and the Mosoni Danube, in Hungarian territory, constitutes the Szigetköz. Cunovo and, further downstream, Gabcíkovo, are situated in this sector of the river on Slovak territory, Cunovo on the right bank and Gabcíkovo on the left. Further downstream, after the confluence of the various branches, the river enters Hungarian territory and the topography becomes hillier. Nagymaros lies in a narrow valley at a bend in the Danube just before it turns south, enclosing the large river island of Szentendre before reaching Budapest (see sketch-map No. 1 - 85 kb).

17. 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.

18. 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" (see sketch-map No. 2 - 85 kb). The Court will subsequently have occasion to revert in more detail to those works, which were to

comprise, inter alia, a reservoir upstream of Dunakiliti, in Hungarian and Czechoslovak territory; a dam at Dunakiliti, in Hungarian territory; a bypass canal, in Czechoslovak territory, on which was to be constructed the Gabcíkovo System of Locks (together with a hydroelectric power plant with an installed capacity of 720 megawatts (MW)); the deepening of the bed of the Danube downstream of the place at which the bypass canal was to rejoin the old bed of the river; a reinforcement of flood-control works along the Danube upstream of Nagymaros; the Nagymaros System of Locks, in Hungarian territory (with a hydroelectric power plant of a capacity of 158 MW); and the deepening of the bed of the Danube downstream.

Article 1, paragraph 4, of the Treaty further provided that the technical specifications concerning the system would be included in the "Joint Contractual Plan" which was to be drawn up in accordance with the Agreement signed by the two Governments for this purpose on 6 May 1976; Article 4, paragraph 1, for its part, specified that "the joint investment [would] be carried out in conformity with the joint contractual plan".

According to Article 3, paragraph 1,

"Operations connected with the realization of the joint investment and with the performance of tasks relating to the operation of the System of Locks shall be directed and supervised by the Governments of the Contracting Parties through . . . ( . . . ,government delegates,)."

Those delegates had, inter alia, "to ensure that construction of the System of Locks is . . . carried out in accordance with the approved joint contractual plan and the Project work schedule". When the works were brought into operation, they were moreover "To establish the operating and operational procedures of the System of Locks and ensure compliance therewith."

Article 4, paragraph 4, stipulated that:

"Operations relating to the joint investment [should] be organized by the Contracting Parties in such a way that the power generation plants [would] be put into service during the period 1986-1990."

Article 5 provided that the cost of the joint investment would be borne by the contracting parties in equal measure. It specified the work to be carried out by each one of them. Article 8 further stipulated that the Dunakiliti dam, the bypass canal and the two series of locks at Gabcíkovo and Nagymaros would be "jointly owned" by the contracting parties "in equal measure". Ownership of the other works was to be vested in the State on whose territory they were constructed.

The parties were likewise to participate in equal measure in the use of the system put in place, and more particularly in the use of the base-load and peak-load power generated at the hydroelectric power plants (Art. 9).

According to Article 10, the works were to be managed by the State on whose territory they were located, "in accordance with the jointly-agreed operating and operational procedures", while Article 12 stipulated that the operation, maintenance (repair) and reconstruction costs of jointly owned works of the System of Locks were also to be borne jointly by the contracting parties in equal measure.

According to Article 14,

"The discharge specified in the water balance of the approved joint contractual plan shall be ensured in the bed of the Danube [between Dunakiliti and Sap] unless natural conditions or other circumstances temporarily require a greater or smaller discharge."

Paragraph 3 of that Article was worded as follows:

"In the event that the withdrawal of water in the Hungarian-Czechoslovak section of the Danube exceeds the quantities of water specified in the water balance of the approved joint contractual plan and the excess withdrawal results in a decrease in the output of electric power, the share of electric power of the Contracting Party benefiting from the excess withdrawal shall be correspondingly reduced."

Article 15 specified that the contracting parties "shall ensure, by the means specified in the joint contractual plan, that the quality of the water in the Danube is not impaired as a result of the construction and operation of the System of Locks".

Article 16 set forth the obligations of the contracting parties concerning the maintenance of the bed of the Danube.

Article 18, paragraph 1, provided as follows:

"The Contracting Parties, in conformity with the obligations previously assumed by them, and in particular with article 3 of the Convention concerning the regime of navigation on the Danube, signed at Belgrade on 18 August 1948, shall ensure uninterrupted and safe navigation on the international fairway both during the construction and during the operation of the System of Locks."

It was stipulated in Article 19 that:

"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."

Article 20 provided for the contracting parties to take appropriate measures, within the framework of their national investments, for the protection of fishing interests in conformity with the Convention concerning Fishing in the Waters of the Danube, signed at Bucharest on 29 January 1958.

According to Article 22, paragraph 1, of the Treaty, the contracting parties had, in connection with the construction and operation of the System of Locks, agreed on minor revision to the course of the State frontier between them as follows:

" (d)In the Dunakiliti-Hrušov head-water area, the State frontier shall run from boundary point 161.V.O.á. to boundary stone No. I.5. in a straight line in such a way that the territories affected, to the extent of about 10-10 hectares shall be offset between the two States."

It was further provided, in paragraph 2, that the revision of the State frontier and the exchange of territories so provided for should be effected "by the Contracting Parties on the basis of a separate treaty". No such treaty was concluded.

Finally a dispute settlement provision was contained in Article 27, worded as follows:

"1. The settlement of disputes in matters relating to the realization and operation of the System of Locks shall be a function of the government delegates.

2. If the government delegates are unable to reach agreement on the matters in dispute, they shall refer them to the Governments of the Contracting Parties for decision."

19. The Joint Contractual Plan, referred to in the previous paragraph, set forth, on a large number of points, both the objectives of the system and the characteristics of the works. In its latest version it specified in paragraph 6.2 that the Gabcíkovo bypass canal would have a discharge capacity of 4,000 cubic metres per second (m ³/s). The power plant would include "Eight . . . turbines with 9.20 m diameter running wheels" and would "mainly operate in peak-load time and continuously during high water". This type of operation would give an energy production of 2,650 gigawatt/hours (GWh) per annum. The plan further stipulated in paragraph 4.4.2:

"The low waters are stored every day, which ensures the peak load time operation of the Gabcíkovo hydropower plant . . . a minimum of 50 m ³/s additional water is provided for the old bed [of the Danube] besides the water supply of the branch system."

The Plan further specified that, in the event that the discharge into the bypass canal exceeded 4,000-4,500 m ³/s, the excess amounts of water would be channelled into the old bed. Lastly, according to paragraph 7.7 of the Plan:

"The common operational regulation stipulates that concerning the operation of the Dunakiliti barrage in the event of need during the growing season 200 m ³/s discharge must be released into the old Danube bed, in addition to the occasional possibilities for rinsing the bed."

The Joint Contractual Plan also contained "Preliminary Operating and Maintenance Rules", Article 23 of which specified that "The final operating rules [should] be approved within a year of the setting into operation of the system." (Joint Contractual Plan, Summary Documentation, Vol. O-1-A.)

Nagymaros, with six turbines, was, according to paragraph 6.3 of the Plan, to be a "hydropower station . . . type of a basic power-station capable of operating in peak-load time for five hours at the discharge interval between 1,000-2,500 m ³/s" per day. The intended annual production was to be 1,025 GWh (i.e., 38 per cent of the production of Gabcíkovo, for an installed power only equal to 21 per cent of that of Gabcíkovo).

20. 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.

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21. The schedule of work had for its part been fixed in an Agreement on mutual assistance signed by the two parties on 16 September 1977, at the same time as the Treaty itself. The Agreement moreover made some adjustments to the allocation of the works between the parties as laid down by the Treaty.

Work on the Project started in 1978. On Hungary,s initiative, the two parties first agreed, by two Protocols signed on 10 October 1983 (one amending Article 4, paragraph 4, of the 1977 Treaty and the other the Agreement on mutual assistance), to slow the work down and to postpone putting into operation the power plants, and then, by a Protocol signed on 6 February 1989 (which amended the Agreement on mutual assistance), to accelerate the Project.

22. 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.

23. During this period, negotiations were being held between the parties. Czechoslovakia also started investigating alternative solutions. One of them, subsequently known as "Variant C", entailed a unilateral diversion of the Danube by Czechoslovakia on its territory some 10 kilometres upstream of Dunakiliti (see sketch-map No. 3 - 88 kb). In its final stage, Variant C included the construction at Cunovo of an overflow dam and a levee linking that dam to the south bank of the bypass canal. The corresponding reservoir was to have a smaller surface area and provide approximately 30 per cent less storage than the reservoir initially contemplated. Provision was made for ancillary works, namely: an intake structure to supply the Mosoni Danube; a weir to enable, inter alia, floodwater to be directed along the old bed of the Danube; an auxiliary shiplock; and two hydroelectric power plants (one capable of an annual production of 4 GWh on the Mosoni Danube, and the other with a production of 174 GWh on the old bed of the Danube). The supply of water to the side-arms of the Danube on the Czechoslovak bank was to be secured by means of two intake structures in the bypass canal at Dobrohošt, and Gabcíkovo. A solution was to be found for the Hungarian bank. Moreover, the question of the deepening of the bed of the Danube at the confluence of the bypass canal and the old bed of the river remained outstanding.

On 23 July 1991, the Slovak Government decided "to begin, in September 1991, construction to put the Gabcíkovo Project into operation by the provisional solution". That decision was endorsed by the Federal Czechoslovak Government on 25 July. Work on Variant C began in November 1991. Discussions continued between the two parties but to no avail, and, on 19 May 1992, the Hungarian Government transmitted to the Czechoslovak Government a Note Verbale terminating the 1977 Treaty with effect from 25 May 1992. On 15 October 1992, Czechoslovakia began work to enable the Danube to be closed and, starting on 23 October, proceeded to the damming of the river.

24. On 23 October 1992, the Court was seised of an "Application of the Republic of Hungary v. The Czech and Slovak Federal Republic on The Diversion of the Danube River"; however, Hungary acknowledged that there was no basis on which the Court could have founded its jurisdiction to entertain that application, on which Czechoslovakia took no action. In the meanwhile, the Commission of the European Communities had offered to mediate and, during a meeting of the two parties with the Commission held in London on 28 October 1992, the parties entered into a series of interim undertakings. They principally agreed that the dispute would be submitted to the International Court of Justice, that a tripartite fact-finding mission should report on Variant C not later than 31 October, and that a tripartite group of independe