The judgment of the General Court regarding the Fehmarn project annulled the Commission’s approval of the aid following a preliminary procedure. The judgment is one of many that add a new angle to the previous Case law. Prior to these new Cases, serious difficulties resulting in a formal investigation either required that the circumstances of the case were very complicated (and the complexity to be related to the assessment of the comparability of the measure) or that the Commission had failed to investigate legal aspects. In the Fehmarn Case, the General Court concluded that serious difficulties were present due to the Commission’s failure to investigate the facts of the matter carefully and with sufficient detail. The General Court has thereby limited the Commission’s margin of discretion. If this is truly the case, Member States and the Commission will have to consider even more carefully in the future whether to seek a formal investigation that will prolong the approval process, or rely on a decision reached after the preliminary investigation whereby it may be subject to complaints, and scrutiny by the General Court – and even the Court of Justice, causing further delays.