Article 6(1) of Directive 93/13 on unfair terms in consumer contracts must be interpreted as precluding national case-law that temporally limits the restitutory effects connected with a finding of unfairness by a court, in accordance with Article 3(1) of that directive, in respect of a clause contained in a contract concluded between a consumer and a seller or supplier, to amounts overpaid under such a clause after the delivery of the decision in which the finding of unfairness is made.

Article 6(1) of Directive 93/13 must be interpreted as meaning that a contractual term held to be unfair must be regarded, in principle, as never having existed, so that it cannot have any effect on the consumer. Therefore, the determination by a court that such a term is unfair must, in principle, have the consequence of restoring the consumer to the legal and factual situation that he would have been in if that term had not existed. It follows that the obligation for the national court to exclude an unfair contract term imposing the payment of amounts that prove not to be due entails, in principle, a corresponding restitutory effect in respect of those same amounts. The absence of such restitutory effect would be liable to call into question the dissuasive effect that Article 6(1) of Directive 93/13, read in conjunction with Article 7(1) of that directive, is designed to attach to a finding of unfairness in respect of terms in contracts concluded between consumers and sellers or suppliers.

In addition, the regulation by national law of the protection guaranteed to consumers by Directive 93/13 may not alter the scope and, therefore, the substance of that protection and thus affect the strengthening of the effectiveness of that protection by the adoption of uniform rules of law in respect of unfair terms, which was the intention of the EU legislature, as stated in recital 10 of Directive 93/13. Consequently, while it is for the Member States, by means of their national legislation, to define the detailed rules under which the unfairness of a contractual clause is established and the actual legal effects of that finding are produced, the fact remains that such a finding must allow the restoration of the legal and factual situation that the consumer would have been in if that unfair term had not existed, by inter alia, creating a right to restitution of advantages wrongly obtained, to the consumer’s detriment, by the seller or supplier on the basis of that unfair term.

In that context, the provisions of national law to which Article 6(1) of Directive 93/13 refers may not adversely affect the substance of the right that consumers acquire under that provision not to be bound by a term deemed to be unfair.

It follows that national case-law concerning the temporal limitation of the legal effects resulting, in accordance with Article 6(1) of Directive 93/13, from the finding that a contractual term is unfair, ensures only limited protection for consumers. Such protection is, therefore, incomplete and insufficient and does not constitute either an adequate or effective means of preventing the continued use of that type of term, contrary to Article 7(1) of Directive 93/13. In those circumstances, the referring courts, being bound for the purposes of the decisions to be given in the main proceedings by the interpretation of EU law given by the Court, must disapply, of their own motion, the temporal limitation resulting from such case-law, because that limitation does not appear to be compatible with that law.

Consequently, Article 6(1) of Directive 93/13 must be interpreted as precluding national case-law that temporally limits the restitutory effects connected with a finding of unfairness by a court, in accordance with Article 3(1) of that directive, in respect of a clause contained in a contract concluded between a consumer and a seller or supplier, to amounts overpaid under such a clause after the delivery of the decision in which the finding of unfairness is made.

(see paras 61-63, 65, 66, 71, 73-75, operative part)