Case concerning Gabcikovo-Nagymaros project (Hungary/Slovakia). Judgement

Hungary and Czechoslovakia in 1977 concluded a treaty for the building of dam structures in Slovakia and Hungary for the production of electric power, flood control and improvement of navigation on the Danube. In 1989 Hungary suspended and subsequently abandoned completion of the project alleging that it entailed grave risks to the Hungarian environment and the water supply of Budapest. Slovakia (successor to Czechoslovakia) denied these allegations and insisted that Hungary carry out its treaty obligations. It planned and subsequently put into operation an alternative project only on Slovak territory, whose operation had effects on Hungary's access to the water of the Danube. In this judgement, the Court found: (1) that Hungary was not entitled to suspend and subsequently abandon, in 1989, its part of the works in the dam project, as laid down in the treaty signed in 1977 by Hungary and Czechoslovakia and related instruments; (2) that Czechoslovakia was entitled ti start, in November 1991, preparation of an alternative provisional solution (called Variant C), but not to put that solution into operation in October 1992 as a unilateral measure; (3) that Hungary's notification of termination of the 1977 Treaty and related instruments on 19 May 1992 did not legally terminate them (and they are consequently still in force and govern the relationship between the Parties); (4) and that Slovakia, as successor to Czechoslovakia became a party the Treaty of 1997.As to the future conduct of the Parties, the Court found: (1) that Hungary and Slovakia must negotiate in good faith in the light of the prevailing situation, and must take all necessary measures to ensure the achievement of the objectives of the 1997 Treaty; (2) that, unless the Parties agree otherwise, a joint operational regime for the dam on Slovak territory must be established in accordance with the Treaty of 1977; (3) that each Party must compensate the other Party for the damage caused by its conduct; (4) and that the accounts for the construction and operation of the works must be settled in accordance with the relevant provisions of the 1977 Treaty and its related instruments