This is an Opinion Statement prepared by the CFE ECJ Task Force1 on the Engie case, in which the Court of Justice of the EU (Grand Chamber) delivered its decision on 5 December 2023. The Engie case concerns the question whether tax rulings issued by Luxembourg to companies part of the French energy group Engie, are compatible with primary EU law, notably rules on State aid; and, whether, and to what extent, the Commission can invoke the concept of “abuse of law” for a State aid challenge of ex ante tax assessment issued by a tax authority of a Member state in the form of a tax ruling. The Court set aside the General Court judgment of 12 May 2021, which initially upheld the European Commission findings of State aid. The CJEU’s Grand Chamber found that the European Commission did not establish to the appropriate legal standard that the tax rulings related to the zero-interest convertible loan (ZORA) provided selective advantage for the Engie entities. It did not establish the correct reference framework for assessment of State aid by way of excluding the legal basis for the tax ruling practice from the reference framework itself (Articles 164 and 166 LIR). By establishing an erroneous reference framework, the Commission relied on a wrongfully based selectivity analysis, a key step in establishing State aid for purposes of Article 107(1) TFEU. Finally, the Court established that the Commission cannot invoke national anti-abuse rules to establish selectivity in a situation where the non-application of the “abuse of law” concept by tax authorities unless the non-application of the anti-abuse provisions is based on derogation from national law or administrative practice on anti-abuse provisions comparable to the case at issue (in concreto). Thus, the Grand Chamber judgment follows the Opinion of AG Kokott delivered on 4 May 2023.3The Court, however, opened the door for establishing selectivity of tax rulings such as those in the Engie case, where the basis for taxation consists of pre-agreed margin (mark-up), approved ...