4.  The applicants were born in 1914, 1920, 1921 and 1945 respectively. The first lives in Timişoara, the second in Delémont (Switzerland) and the others in Arad. 5.  The first two applicants and their deceased brother, Mircea Stoinescu, whose heirs are the other two applicants, were the owners of a house in Arad. In 1950 the State took possession of that house under Decree no. 92/1950 on nationalisation. The house was converted into four flats intended for rental. 6.  On 27 September 1993 the first two applicants and Mircea Stoinescu brought an action for the recovery of possession of immovable property in the Arad Court of First Instance against Arad Town Council and R., a State-owned company responsible for the management of property belonging to the State. After the death of Mircea Stoinescu, the action was pursued by his heirs, Mrs Felicia Stoinescu and Mrs Maria Tăucean. The applicants sought a declaration that they were the rightful owners of the house and appurtenant land that the State had, in their opinion, wrongfully seized in 1950. They claimed that, under Article 2 of Decree no. 92/1950, property belonging to persons in certain social categories was not subject to nationalisation, and that they fell within such a category. In their view, the nationalisation of the house in question had therefore been improper and unlawful. 7.  In a judgment of 12 April 1994, the Arad Court of First Instance dismissed the applicants' action, refusing to rule on the merits on the ground that they could not obtain redress for the damage they had sustained until the enactment of special legislation introducing reparation measures. The judgment was upheld by the Arad County Court on 3 November 1995. The applicants appealed against that decision. 8.  In 1996 the tenants of the flats making up the house applied to purchase them, relying on Law no. 112/1995. Arad Town Council informed the R. company that a dispute was pending concerning the title to the house and instructed it not to pursue the sale of the flats in question. 9.  Consequently, the tenants of three flats had their purchase applications rejected, but not H.D. (a former football player and international celebrity) and his wife, to whom the R. company sold flat no. 3 on 18 December 1996. 10.  On 25 February 1997 the Timişoara Court of Appeal upheld an appeal by the applicants and remitted the case to the Arad Court of First Instance for a decision on the merits. 11.  On 12 May 1997 Mr and Mrs D. applied to intervene in the Court of First Instance proceedings on the ground that they had been the owners of flat no. 3 since its sale on 18 December 1996. 12.  Further to the couple's application to intervene, the applicants requested the court to find that the sale of flat no. 3 was null and void. In their view, as the nationalisation had been improper and unlawful, the State could not have been the rightful owner of the property and thus could not lawfully have sold any part of it. The applicants relied in particular on Article 966 of the Civil Code, whereby an undertaking entered into on an erroneous or unlawful basis could not produce any useful effect. 13.  On 7 June 1997 the Arad Court of First Instance held that the nationalisation of the house had been unlawful and that the applicants were therefore the rightful owners. However, the court rejected the request for the rescission of the contract of sale between the State and Mr and Mrs D., on the ground that the couple had made the purchase in good faith. 14.  The applicants appealed against that judgment. On 28 November 1997 the Arad County Court allowed the appeal and remitted the case to the Court of First Instance for reconsideration. 15.  In a judgment of 6 July 1998, the Arad Court of First Instance held that the nationalisation of the house had been unlawful, that the applicants were the rightful owners and that the contract of sale between the State and Mr and Mrs D. was null and void. 16.  On 2 February 1999 the Arad County Court allowed an appeal by Mr and Mrs D. and dismissed the applicants' action, finding that the nationalisation had been lawful and that, consequently, the sale by the State of flat no. 3 was also lawful. 17.  The applicants appealed to the Timişoara Court of Appeal, which gave its judgment on 30 June 1999. It partly allowed the applicants' appeal in so far as it found the nationalisation to have been unlawful and acknowledged that they had remained the rightful owners of the property. However, it dismissed the appeal as regards the rescission of the sale of flat no. 3, considering that the State had been presumed to be the owner of the property at the time of the sale, in spite of the dispute over the property that was pending in the courts. It moreover relied on the fact that Law no. 112/1995, which had formed the statutory basis for the sale of the property, did not provide for any penalty in respect of property sold when the title to it was in dispute before the courts. The Court of Appeal did not address the applicants' argument relating to the principle of unjust enrichment (see paragraph 27 below). 18.  On 20 August 2001 the applicants again requested the Arad Court of First Instance to order the rescission of the sale of flat no. 3, contending that the purchasers had broken the law. Their action was dismissed on 13 December 2001 on the ground that the matter had become res judicata.