“93. The court has consistently held that individuals are entitled to obtain repayment of charges levied in a member state in breach of Community provisions. That right is the consequence and the complement of the rights conferred on individuals by Community provisions as interpreted by the court. The member state in question is therefore required, in principle, to repay charges levied in breach of Community law (see, in particular, the Comateb case (para 20), Metallgesellschaft Ltd v IRC, Hoechst AG v IRC Joined cases C-397/98 and C-410/98 [2001] All ER (EC) 496,[2001] ECR I-1727 (para 84) and the Marks & Spencer case (para 30)). 94. According to the case law, there is only one exception to that obligation to make repayment. A member state may resist repayment to the trader of a charge levied though not due only where it is established by the national authorities that the charge has been borne in its entirety by someone other than the taxable person and that reimbursement of the charge would constitute unjust enrichment of the latter. It follows that, if the burden of the charge has been passed on only in part, the national authorities are required to repay the amount not passed on (see to that effect, in particular, the Comateb case (paras 27, 28)).”
“67. Where such a rule applies to claims in respect of situations which arose before its enactment, that effect does not seem to me incompatible with Community law. On the one hand, in so far as it seeks to preclude unjust enrichment, it in fact precludes only enrichment which would have occurred after its enactment, provided that there is no provision for recovery of any amount already reimbursed. On the other hand, there can in any event be no legitimate expectation of any such enrichment, since the very concept of legitimacy cannot embrace what is unjust.”
“ 69…since Community law does not require a right to reimbursement at all where unjust enrichment would ensue, the fact that, following a change to national law, a claim which might previously have succeeded can on that ground no longer succeed has no impact on the effectiveness of a right conferred by Community law.”
“92. It must be concluded on this point, therefore, that the adoption by a member state of rules which retroactively restrict the right to repayment of a sum levied but not due, in order to forestall the possible effects of a judgment of the court holding that Community law precludes the maintenance of a national duty, is contrary to Community law and, more particularly, to art 10 EC only in so far as it is aimed specifically at that duty, a point which falls to be determined by the national court. Accordingly, the fact that such a measure has retroactive effect does not in itself amount to an infringement of Community law, where the measure is not aimed specifically at the duty which formed the subject matter of a judgment of the court.”
“65. The limitation of the temporal effect of the ruling in the EKW judgment does not mean that whenever a person had raised a claim before the date of the judgment that claim must be free from any other restriction laid down by national law but rather that, in relation to the period specified, no other claims may be allowed to proceed. Nor is there is anything in the judgment which itself imposes or implies any general condition as to the date of enactment of any applicable national rules or which precludes any retroactive effect thereof. ”
“20. It appears that a large number of claims had in fact been raised, in one form or another, before the date of the judgment in the EKW case (when the court had been informed of a total which might have to be reimbursed if all claims were to succeed, but not of the number of claims estimated to have been brought already). In its observations in the present case, the Austrian government states that 16,000 such claims, representing some ATS 3,000m, are pending for Vienna alone, and suggests that their number is due at least in part to the fact that the Verwaltungsgerichtshof has decided that the concept of 'equivalent administrative claims', used by the court in the EKW judgment, must be given a broad interpretation.”
“… the general principle of equal treatment requires that similar situations are not treated differently unless differentiation is objectively justified”