Judgment of the Court (Fourth Chamber) of 18 December 2025.#Electrabel SA and Others v Commission de Régulation de l’Electricité et du Gaz (CREG).#Request for a preliminary ruling from the Cour d'appel de Bruxelles.#Reference for a preliminary ruling – Internal market for electricity – Regulation (EU) 2022/1854 – Emergency intervention to address high energy prices – Article 2(5) and (9) – Articles 6 to 8 – Cap on market revenues obtained by electricity producers using certain energy sources – Determination of ‘market revenues’ – National legislation providing for the use of presumptions that are either irrebuttable or rebuttable by means of other presumptions – Principle of proportionality – Article 22(2)(c) – Period of application of Articles 6 to 8 of that regulation – Application of a measure capping revenue for a period prior to that provided for in that regulation, pursuant to national legislation adopted after the entry into force of that regulation – Principles of the primacy and effectiveness of EU law – Principle of sincere cooperation.#Case C-633/23.