It cannot be accepted that the Commission is not entitled to refer directly to the Court of Justice for the purposes of a declaration that a Member State has failed to comply with a decision taken as part of the monitoring of State aid in the event that the Council makes use, exceptionally, of the power which the Commission normally exercises. In particular, where the infringement which the Commission considers to have been committed is linked to the granting of new aid, it is entitled to exercise the powers conferred on it by Article 108 TFEU for the purposes of reviewing the compatibility of that aid with the internal market. In that context, the Commission must take into account all relevant matters, including, where appropriate, the circumstances already considered in any previous decision and any conditions which that decision may have imposed on the Member State concerned. Furthermore, the Commission may take into account any new information likely to alter the analysis previously carried out. In the absence of such information, the Commission is entitled to base its new decision on the assessments made in the earlier decision and on the failure to comply with the conditions imposed by that decision.

The possibility, for the Commission, of classifying as new, and where necessary unlawful, aid not only the alteration of existing aid, but also all the existing aid to which that alteration relates, is subject, as regards the substance, to the condition that the Commission establish that that alteration affects the very substance of the pre-existing measure. Furthermore, in the event that the Member Sate concerned submits, during the administrative procedure, either that that alteration is clearly severable from the pre-existing measure, or that it is purely formal or administrative in character and is not capable of influencing the assessment of the compatibility of that measure with the internal market, the Commission must justify why those arguments appear to it to be unfounded.

Where the Commission detects a failure to comply with a decision which declared aid or an aid scheme compatible with the internal market subject to certain conditions, it may either obtain a direct finding of that failure by the Court of Justice or, if that failure consists in the granting of new aid, exercise the powers enabling it to monitor the latter, provided that it meets the related substantive and procedural requirements. If the Commission chooses to exercise its monitoring powers, it must in principle confine itself to examining the new aid. It is only provided that it is demonstrated that the latter has altered the actual substance of existing aid or an existing aid scheme that the Commission is, by way of exception, entitled to declare that all of that pre-existing measure, as altered, is incompatible with the internal market, to find that it is unlawful if the Commission was also not made aware of that alteration prior to its implementation and to order, therefore, the withdrawal or modification of the altered aid or aid scheme.

By contrast, the Commission is not entitled to take the view that failure to comply with a condition imposed at the time of approving an existing aid scheme involves, ipso facto, the ‘reclassification’ of that measure as new aid, and still less to consider the latter as unlawful ab initio and to order its recovery as if it were aid that had been unlawfully implemented and not aid authorised in advance.

In the first place, any existing aid is covered by the authorisation decision relating to it, except where the Commission considers that it has been misused or that its very substance has been altered by new aid. Subject to those two situations, such aid must therefore be regarded as lawful so long as the Commission has not found that it is incompatible with the internal market.

Next, having regard to the objective pursued by such conditions, any subsequent failure to comply with them can lead the Commission to call into question, by having recourse to one of the various legal remedies provided for by the FEU Treaty and Regulation No 659/1999, only the benefit of the declaration of compatibility with the internal market granted to the measure at issue, and not its classification as existing aid.

Furthermore, since the existing aid may, in accordance with Article 108(1) TFEU, be properly implemented as long as the Commission has not found it to be incompatible, that declaration of incompatibility can produce effects only in the future.

Failing that, a properly implemented aid scheme and individual aid lawfully granted under that scheme before the Member State concerned fails to fulfil its obligations would be retroactively deemed to constitute aid which is unlawful and incompatible with the internal market. Such a result would amount to revocation of the decision authorising the implementation of those measures. As is clear from recital 10 and Article 9 of Regulation No 659/1999, such a sanction was provided for by the legislature only in the specific situation where a decision taken as part of State aid monitoring is based on incorrect information.

Lastly, Regulation No 659/1999 was adopted, inter alia, in order to ensure legal certainty in procedural matters, in particular as regards the treatment of existing aid and unlawful aid. That regulation lays down a set of rules enabling the Commission to ensure compliance with decisions adopted in the context of monitoring State aid, and in particular to deal with a situation in which the Member State concerned fails to comply with one of the conditions accompanying the declaration of compatibility and to draw from it all the appropriate legal conclusions.

(see paras 85-91)