50      Enfin, dans ce dernier arrêt, le Tribunal a apprécié la portée du diplôme de l’université de Poitiers délivré à M. Brouillard au regard des exigences d’un autre avis de concours, publié par la Cour de justice de l’Union européenne pour pourvoir à ses besoins en traduction de textes juridiques, et non au regard de l’avis de concours concerné dans la présente affaire. Or, l’autorité de la chose jugée ne s’attache qu’aux points de fait et de droit qui ont été effectivement ou nécessairement tranchés par la décision judiciaire en cause (arrêt du 19 février 1991, Italie/Commission, C‑281/89, EU:C:1991:59, point 14, et ordonnance du 28 novembre 1996, Lenz/Commission, C‑277/95 P, EU:C:1996:456, point 50). Par conséquent, lorsque, dans l’arrêt attaqué, il a apprécié la portée du diplôme de l’université de Poitiers au regard de l’avis de concours en cause dans la présente affaire, le Tribunal n’était pas tenu de respecter la chose jugée par son arrêt du 14 septembre 2015, Brouillard/Cour de justice (T‑420/13, non publié, EU:T:2015:633), ni, par voie de conséquence, de justifier des raisons pour lesquelles il entendait s’écarter des appréciations contenues dans cet arrêt.

46     As stated in paragraph 38 above, it is for the Commission to prove that the rules of the common organisation of the agricultural markets have been infringed (see also to that effect Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 19, and Case C-253/97 Italy v Commission [1999] ECR I-7529, paragraph 6).

33     It should also be noted that it is for the Commission to prove an infringement of the rules on the common organisation of the agricultural markets (see, in particular, Case C‑281/89 Italy v Commission [1991] ECR I‑347, paragraph 19). The Commission is therefore obliged to give reasons for its decision finding an absence of, or defects in, inspection procedures operated by the Member State in question (see Case C‑349/97 Spain v Commission, paragraph 46).

44 In that connection, it should be observed that, in paragraph 77 of the contested judgment, the Court of First Instance rightly pointed out that the principle of res judicata extends only to matters of fact and law actually or necessarily settled by the judicial decision in question (Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 14, and Case C-277/95 Lenz v Commission [1996] ECR I-6109, paragraph 50).

37 The reason for this mitigation of the burden of proof on the Commission is that it is the State which is best placed to collect and check the data required for the clearance of EAGGF accounts, and which is consequently required to adduce the most detailed and comprehensive evidence that its figures are accurate and, if appropriate, that the Commission's calculations are incorrect (Netherlands v Commission, cited above, paragraph 17; Case C-59/97 Italy v Commission [1999] ECR I-1683, paragraph 55). In the event of a dispute, it is for the Commission to prove that the rules of the common organisation of the agricultural markets have been infringed and, once it has established such an infringement, the Member State concerned must then, if appropriate, demonstrate that the Commission made an error as to the financial consequences to be inferred from that infringement (Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 19, Netherlands v Commission, cited above, paragraph 18, and Case C-59/97 Italy v Commission, cited above, paragraph 55).

7 As the Court has held, only intervention undertaken in accordance with the Community rules within the framework of the common organisation of agricultural markets is to be financed by the EAGGF (see Case C-253/97 Italy v Commission [1999] ECR I-7529, paragraph 6). In that context, it is for the Commission to prove an infringement of the rules on the common organisation of the agricultural markets (see Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 19; Case C-55/91 Italy v Commission [1993] ECR I-4813, paragraph 13; and Case C-253/97, cited above, paragraph 6). Accordingly, the Commission is obliged to give reasons for its decision finding an absence of, or defects in, inspection procedures operated by the Member State in question (Case C-8/88 Germany v Commission [1990] ECR I-2321, paragraph 23).

It should be noted in this connection that it is for the Commission to prove an infringement of the rules on the common organisation of the agricultural markets (see Case C-281/89

6 As the Court has already observed, only intervention undertaken in accordance with the Community rules within the framework of the common organisation of agricultural markets is to be financed by the EAGGF (see Case C-48/91 Netherlands v Commission [1993] ECR I-5611, paragraph 14). In that context, it is for the Commission to prove an infringement of the rules on the common organisation of the agricultural markets (see Case 347/85 United Kingdom v Commission [1988] ECR 1749, paragraph 16; Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 19; Case C-55/91 Italy v Commission [1993] ECR I-4813, paragraph 13; and Case C-48/91, cited above, paragraph 18). Accordingly, the Commission is obliged to give reasons for its decision finding an absence of, or defects in, inspection procedures operated by the Member State in question (Case C-8/88 Germany v Commission [1990] ECR I-2321, paragraph 23).

34 The reason for this mitigation of the burden of proof on the Commission is that it is the State which is best placed to collect and check the data required for the clearance of EAGGF accounts, and which is consequently required to adduce the most detailed and comprehensive evidence that its figures are accurate and, if appropriate, that the Commission's calculations are incorrect (Netherlands v Commission, cited above, paragraph 17; Case C-59/97 Italy v Commission [1999] ECR I-1683, paragraph 55). In the event of a dispute, it is for the Commission to prove that the rules of the common organisation of the agricultural markets have been infringed and, once it has established such an infringement, the Member State concerned must then, if appropriate, demonstrate that the Commission committed an error as to the financial consequences to be inferred from that infringement (Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 19, and Netherlands v Commission, cited above, paragraph 18).

55 Where the Commission refuses to charge certain expenditure to the EAGGF on the ground that it was incurred as a result of breach of Community rules for which a Member State can be held responsible, it is for that State to show that the conditions for obtaining the financing refused are fulfilled (see Case 347/85 United Kingdom v Commission [1988] ECR 1749, paragraph 14, and Case C-48/91 Netherlands v Commission [1993] ECR I-5611, paragraph 16). The Commission is not required to demonstrate that there are irregularities in the data submitted by Member States, it is sufficient for it to show that it has serious and reasonable doubts. The reason for this mitigation of the burden of proof on the Commission is that it is the State which is best placed to collect and check the data required for the clearance of EAGGF accounts, and which is consequently required to adduce the most detailed and comprehensive evidence that its figures are accurate and, if appropriate, that the Commission's calculations are incorrect (Netherlands v Commission, cited above, paragraph 17). In the event of a dispute, it is for the Commission to prove that the rules of the common organisation of the agricultural markets have been infringed and, once it has established such an infringement, the Member State concerned must then, if appropriate, demonstrate that the Commission committed an error as to the financial consequences to be drawn from it (Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 19, and Netherlands v Commission, cited above, paragraph 18).

58 As the Court has already observed, only intervention undertaken in accordance with the Community rules within the framework of the common organisation of agricultural markets is to be financed by the EAGGF (see Case C-48/91 Netherlands v Commission [1993] ECR I-5611, paragraph 14). In that context, it is for the Commission to prove an infringement of the rules on the common organisation of the agricultural markets (see Case 347/85 United Kingdom v Commission [1988] ECR 1749, paragraph 16; Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 13; Case C-55/91 Italy v Commission [1993] ECR I-4813, paragraph 13; and Case C-48/91, cited above, paragraph 18). Accordingly, the Commission is obliged to give reasons for its decision finding an absence of, or defects in, inspection procedures operated by the Member State in question (Case C-8/88 Germany v Commission [1990] ECR I-2321, paragraph 23).

50 The principle of res judicata extends only to the matters of fact and law actually or necessarily settled by the judicial decision in question (Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 14).

13 As regards the burden of proof, it should next be pointed out that, as far as the financing of the common agricultural policy is concerned, it is first for the Commission to prove an infringement of the rules of the common organization of the agricultural markets. Once such an infringement has been established, the Member State concerned must then, if appropriate, demonstrate that the Commission committed an error as to the financial consequences to be attributed to it (see, in particular, Case C-281/89 Italy v Commission [1991] ECR I-347, paragraph 19).