Judgment of the Court (Grand Chamber) of 3 May 2022.#CityRail a.s. v Správa železnic, státní organizace.#Reference for a preliminary ruling – Article 267 TFUE – Concept of ‘court or tribunal’ – Criteria relating to the body’s constitution and function – Exercise of judicial or administrative functions – Directive 2012/34/EU – Articles 55 and 56 – Single national regulatory body for the railway sector – Independent regulatory authority for the sector – Entitlement to act on an ex-officio basis – Power to impose penalties – Decisions that are open to challenge before the courts – Inadmissibility of the request for a preliminary ruling.#Case C-453/20.