Judgment of the Court (Fifth Chamber) of 18 December 2019.#IT Development SAS v Free Mobile SAS.#Request for a preliminary ruling from the Cour d'appel de Paris.#Reference for a preliminary ruling — Intellectual property — Enforcement of intellectual property rights — Directive 2004/48/EC — Legal protection of computer programs — Directive 2009/24/EC — Software licence agreement — Unauthorised modification of the source code of a computer program by a licensee in breach of the licence agreement — Action for infringement brought by the author of the program against the licensee — Nature of the applicable liability regime.#Case C-666/18.