Judgment of the Court (Fifth Chamber) of 11 November 2021.#MG v Dublin City Council.#Request for a preliminary ruling from the The Labour Court, Ireland.#Reference for a preliminary ruling – Protection of the safety and health of workers – Organisation of working time – Directive 2003/88/EC – Article 2 – Concept of ‘working time’ – Retained firefighter – Stand-by time according to a stand-by system – Pursuit, during the period of stand-by time, of a self-employed professional activity – Constraints arising from the stand-by system.#Case C-214/20.