Judgment_paragraph 56 · Solvay Chimica Italia SpA and Others v Autorità per l'energia elettrica, il gas e il sistema idrico (C-262/17, C-263/17, C-273/17)

56In that regard, although Article 32(1) of Directive 2009/72 leaves the Member States free to take the measures necessary to establish a system of third-party access to transmission or distribution systems, the Member States therefore having authority, in accordance with Article 288 TFEU, over the form and the methods to be used to implement such a system, the fact remains that, having regard to the importance of the principle of open access to transmission or distribution systems, that margin of discretion does not authorise them to depart from that principle except in those cases where that directive lays down exceptions or derogations (see, by analogy, judgment of 22 May 2008, citiworks, C‑439/06, EU:C:2008:298, paragraph 55).