C-872/25

62025CO0872

ORDER OF THE COURT (Chamber determining whether appeals may proceed)

30 June 2026 ( *1 )

(Appeal – Regulation (EU) 2017/2195 – European Union Agency for the Cooperation of Energy Regulators (ACER) – Determination as to whether appeals should be allowed to proceed – Article 170b of the Rules of Procedure of the Court of Justice – Request demonstrating that an issue is significant with respect to the unity, consistency or development of EU law – Appeal allowed to proceed)

In Case C‑872/25 P,

APPEAL under Article 56 of the Statute of the Court of Justice of the European Union, brought on 24 December 2025,

intervener at first instance,

THE COURT (Chamber determining whether appeals may proceed),

composed of T. von Danwitz, Vice-President of the Court, O. Spineanu-Matei and N. Fenger (Rapporteur), Judges,

Registrar: A. Calot Escobar,

having regard to the written procedure,

having regard to the proposal from the Judge-Rapporteur and after hearing the Advocate General, M. Szpunar,

Under the first paragraph of Article 58a of the Statute of the Court of Justice of the European Union, an appeal brought against a decision of the General Court concerning a decision of an independent board of appeal of ACER is not to proceed unless the Court of Justice first decides that it should be allowed to do so.

3

In accordance with the third paragraph of Article 58a of the Statute of the Court of Justice of the European Union, an appeal is to be allowed to proceed, wholly or in part, in accordance with the detailed rules set out in the Rules of Procedure of the Court of Justice, where it raises an issue that is significant with respect to the unity, consistency or development of EU law.

4

Article 170a(1) of the Rules of Procedure provides that, in the situations referred to in the first paragraph of Article 58a of the Statute of the Court of Justice of the European Union, the appellant is to annex to the appeal a request that the appeal be allowed to proceed, setting out the issue raised by the appeal that is significant with respect to the unity, consistency or development of EU law and containing all the information necessary to enable the Court of Justice to rule on that request.

5

8

By the first part, ACER contends that the General Court erred in its assessment of the legal effect of the decision at issue with regard to Swissgrid, the electricity transmission system operator in Switzerland. By failing to take into account that the de jure exclusion of Swissgrid from the European platform for the imbalance netting process (‘the IN Platform’), which that company attributed to that decision, followed directly from Commission Regulation (EU) 2017/2195 of 23 November 2017 establishing a guideline on electricity balancing ( OJ 2017 L 312, p. 6 ), the General Court failed to consider the context in which that decision had been adopted and ACER’s lack of powers to decide on Swissgrid’s participation in that platform.

9

The General Court itself stated, in paragraphs 27, 28, 32 and 36 of the contested judgment, that Swissgrid’s authorisation to participate in the European energy balancing platforms was determined either by Article 1(6) and (7) of Regulation 2017/2195 or by a bilateral agreement concluded between the European Union and the Swiss Confederation, thereby confirming that ACER had no powers to decide on Swissgrid’s participation in the IN Platform. Had the General Court taken that lack of powers into account, it would have found that Swissgrid’s exclusion from participating in the IN Platform did not follow from the contested decision and would have concluded that the appeal brought by Swissgrid before the ACER Board of Appeal was not capable, through its outcome, of procuring an advantage for that company.

13

In paragraphs 62 to 65 of the contested judgment, the General Court erred in considering that private contracts concluded among electricity transmission system operators, and ACER Decision No 13/2020, had the effect of authorising Swissgrid’s participation in that platform.

14

Furthermore, by holding, in paragraph 66 of the contested judgment, that the interpretation of the implementation framework for the IN Platform in the light of Regulation 2017/2195 was not capable of dispelling any doubt as to whether that company could continue to participate in that platform, the General Court introduced a new criterion, relating to the existence of doubt, for assessing the legal effects of an act. Such a criterion is not relevant and disregards the presumption of legality of acts of institutions and bodies of the European Union, the principle of legal certainty, the rule of law and the principle iura novit curia . According to ACER, there could be no doubt on that point, since Swissgrid’s participation in that platform was clearly excluded in the light of the assessments set out in paragraphs 27 to 33 and 35 to 39 of the contested judgment.

15

Moreover, the General Court contradicted itself by stating, on the one hand, that ACER had the competence to exclude Swissgrid from participating in the IN Platform and, on the other, that that exclusion was determined either by Article 1(6) and (7) of Regulation 2017/2195 or by a bilateral agreement.

19

First of all, such a possibility would be contrary to the Court’s case-law according to which the context of the contested act and the powers of the body which adopted it must be taken into account when assessing the admissibility of an appeal brought against that act. Next, such a possibility may lead to the adoption of contradictory grounds in all cases in which a court or administrative appellate body must, in order to rule on the admissibility of an appeal, assess the legal effects of an act of a higher rank than the contested act. Lastly, the approach adopted by the General Court, consisting in finding that there may be a doubt as to the interpretation of a regulation before the courts, would require administrative appellate bodies to consider, when examining the appeals before them, whether the General Court might harbour such doubt, which would undermine the presumption of legality of acts of the institutions and bodies of the European Union, as recalled, inter alia, in the judgment of 12 February 2008, CELF and ministre de la Culture et de la Communication ( C‑199/06 , EU:C:2008:79 ).

Findings of the Court

20

As a preliminary point, it must be recalled that it is for the appellant to demonstrate that the issues raised by its appeal are significant with respect to the unity, consistency or development of EU law (orders of 10 December 2021, EUIPO v The KaiKai Company Jaeger Wichmann, C‑382/21 P , EU:C:2021:1050 , paragraph 20 , and of 24 March 2026, Capella v EUIPO, C‑766/25 P , EU:C:2026:276 , paragraph 15 ).

21

Accordingly, a request that an appeal be allowed to proceed must, in any event, set out clearly and in detail the grounds on which the appeal is based, identify with equal clarity and detail the issue of law raised by each ground of appeal, specify whether that issue is significant with respect to the unity, consistency or development of EU law and set out the specific reasons why that issue is significant according to that criterion. As regards, in particular, the grounds of appeal, the request that an appeal be allowed to proceed must specify the provision of EU law or the case-law that has been infringed by the judgment or order under appeal, explain succinctly the nature of the error of law allegedly committed by the General Court, and indicate to what extent that error had an effect on the outcome of the judgment or order under appeal. Where the error of law relied on results from an infringement of the case-law, the request that the appeal be allowed to proceed must explain, in a succinct but clear and precise manner, first, where the alleged contradiction lies, by identifying the paragraphs of the judgment or order under appeal which the appellant is calling into question as well as those of the ruling of the Court of Justice or the General Court alleged to have been infringed, and, second, the concrete reasons why such a contradiction raises an issue that is significant with respect to the unity, consistency or development of EU law (orders of 10 December 2021, EUIPO v The KaiKai Company Jaeger Wichmann, C‑382/21 P , EU:C:2021:1050 , paragraph 22 , and of 24 March 2026, Capella v EUIPO, C‑766/25 P , EU:C:2026:276 , paragraph 17 ).

26

It is apparent from the request that the appeal be allowed to proceed that ACER is claiming that the General Court, first, disregarded the case-law of the Court of Justice according to which the context of the contested act and the powers of the body which adopted it must be taken into consideration when assessing the admissibility of an appeal. It relies, in particular, on the order of 11 April 2024, Atesos medical and Others v Commission and Others ( C‑491/23 P , EU:C:2024:320 ), the facts of which are said to be similar to those of the present case. According to ACER, the General Court erred in law by failing to take into account, in paragraphs 60 and 61 of the contested judgment, the context in which the decision at issue was adopted, in particular, the fact that the de jure exclusion of Swissgrid from participating in the IN Platform followed from Regulation 2017/2195 and ACER’s lack of competence to authorise Swissgrid’s participation in that platform.

27

Second, as set out in paragraphs 11 to 14 of the present order, ACER alleges a failure to respect the presumption of legality of acts of the institutions and bodies of the European Union, the principle of legal certainty, the rule of law and the principle iura novit curia . It claims that the General Court relied on contradictory grounds as regards Swissgrid’s participation in that platform and ACER’s competence to exclude such participation.

28

In the second place, the request that the appeal be allowed to proceed sets out to the requisite standard the extent to which the alleged errors had an influence on the outcome of the contested judgment. ACER submits that, absent the infringements alleged, the General Court would have made a different assessment of the legal effect of the decision at issue and held that Swissgrid’s appeal against that decision was not capable of procuring an advantage for it.

32

Second, ACER submits that the General Court’s approach in the contested judgment gives rise to a risk of legal uncertainty since it disregards the case-law of the Court of Justice on that issue and, in particular, the case-law recalled in paragraphs 61 to 64 of the order of 11 April 2024, Atesos medical and Others v Commission and Others ( C‑491/23 P , EU:C:2024:320 ).

33

Third and lastly, ACER states that, in considering that there may be a doubt as to the interpretation of a regulation before the courts, the General Court introduced a new and irrelevant criterion for assessing whether the acts of the institutions and bodies of the European Union have ‘direct legal effect’. Such an approach would require administrative appellate bodies, when examining the appeals before them, to consider whether the General Court might harbour such a doubt, thereby calling into question the presumption of legality of those acts, the principle of legal certainty, the rule of law and the principle iura novit curia .

34

In the light of the matters set out by ACER, it must be held that this request that the appeal be allowed to proceed demonstrates to the requisite legal standard that the appeal raises an issue that is significant with respect to the unity, consistency and development of EU law.

Under Article 137 of the Rules of Procedure, applicable to proceedings on appeal pursuant to Article 184(1) of those rules, a decision as to costs is to be given in the judgment or order which closes the proceedings.

38

Accordingly, since the request that the appeal be allowed to proceed must be allowed, the costs must be reserved.

On those grounds, the Court (Chamber determining whether appeals may proceed) hereby orders:

1.

The appeal is allowed to proceed.

President of the Chamber determining whether appeals may proceed

( *1 ) Language of the case: English.