Case C-767/21 P: Judgment of the Court (Third Chamber) of 14 December 2023 — Jérôme Rivière, Dominique Bilde, Joëlle Mélin, Aurélia Beigneux, Thierry Mariani, Jordan Bardella, Jean Paul Garraud, Jean-François Jalkh, Gilbert Collard, Gilles Lebreton, Nicolaus Fest, Gunnar Beck and Philippe Olivier v European Parliament (Appeal — Law governing the institutions — Members of the European Parliament — Rules of Procedure of the European Parliament — Standards of conduct — Rule 10(3) — Prohibition on displaying banners during the sittings of Parliament — Oral measure of the President of the Parliament prohibiting MEPs from displaying national flags on their lecterns — Action for annulment — Article 263 TFEU — Concept of ‘challengeable act’)