39First, as regards the observance of the principle of equality of arms, it must be noted that, if the content of documents setting out an institution’s position in a dispute were to form the subject of public debate, criticism of them could unduly influence the position defended by the institution before the courts in question. In addition, the granting of access to documents relating to an institution’s position in ongoing court proceedings to another party could upset the vital balance between the parties to a dispute, a state of balance which is at the root of the principle of equality of arms, inasmuch as only the institution concerned by a request for access to documents, and not all the parties to the proceedings, would be bound by the obligation of disclosure. Observance of the principle of equality of arms is, however, essential since it is a corollary of the very concept of a fair hearing (see, to that effect, judgments of 21 September 2010, Sweden and Others v API and Commission, C‑514/07 P, C‑528/07 P and C‑532/07 P, EU:C:2010:541, paragraphs 86 and 87 and the case-law cited, and of 28 June 2012, Commission v Éditions Odile Jacob, C‑404/10 P, EU:C:2012:393, paragraph 132).