The EU General Court holds that the compatibility of a State aid depends on the rules that are applicable when aid measures produce effects (Buonotourist)

The Compatibility of State Aid Depends on the Rules which are Applicable at the Time the Aid is Granted Failure to comply with just a single provision of an exemption regulation results in the non-applicability of the whole regulation and makes any implemented aid measure automatically illegal. The compatibility of aid measures adopted in the past but continuing having effects are assessed not on the basis of old rules but on the basis of the rules which are applicable at the moment the aid measures produce effects that fall within the scope of new rules, unless the new rules explicitly exclude them from their scope. Introduction There have been several cases in the past few years where Member States granted aid in the belief that it was compatible with an exemption regulation only