Judgment of the Court (Third Chamber) of 20 May 2021.#X v College van burgemeester en wethouders van de gemeente Purmerend.#Request for a preliminary ruling from the Raad van State.#Reference for a preliminary ruling – Inland transport of dangerous goods – Directive 2008/68/EC – Article 5(1) – Concept of ‘construction requirement’ – Prohibition on laying down more stringent construction requirements – Authority of a Member State requiring a service station to be supplied with liquefied petroleum gas (LPG) only from road tankers fitted with a particular heat-resistant lining not provided for by the European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) – Unlawfulness – Decision legally unchallengeable by a category of persons – Strictly limited possibility of obtaining the annulment of such a decision where there is clear conflict with EU law – Principle of legal certainty – Principle of effectiveness.#Case C-120/19.