Altun and Others

The Court (Grand Chamber) ruled:

Article 14(1)(a) of Council Regulation (EEC) No 1408/71 of 14 June 1971 on the application of social security schemes to employed persons, to self‑employed persons and to members of their families moving within the Community, in the version amended and updated by Council Regulation (EC) No 118/97 of 2 December 1996, as amended by Regulation (EC) No 631/2004 of the European Parliament and of the Council of 31 March 2004, and Article 11(1)(a) of Council Regulation (EEC) No 574/72 of 21 March 1972 laying down rules for the application of Regulation No 1408/71, as amended and updated by Regulation No 118/97, must be interpreted as meaning that, when an institution of a Member State to which workers have been posted makes an application to the institution that issued E 101 certificates for the review and withdrawal of those certificates in the light of evidence, collected in the course of a judicial investigation, which supports the conclusion that those certificates were fraudulently obtained or relied on, and the issuing institution fails to take that evidence into consideration for the purpose of reviewing the grounds for the issue of those certificates, a national court may, in the context of proceedings brought against persons suspected of having used posted workers ostensibly covered by such certificates, disregard those certificates if, on the basis of that evidence and with due regard to the safeguards inherent in the right to a fair trial which must be granted to those persons, it finds the existence of such fraud.