I. Introduction In his recent opinion1 Advocate General Mengozzi addressed an issue which is of pivotal importance for many aid recipients, namely the question whether a decision to open a formal investigation (Article 108(2) TFEU, Article 6(1) of Reg. 659/1999) can have legally binding effect on national courts. Under Article 267 TFEU a German Court had asked the question whether an “uncontested decision of the Commission to initiate a formal investi