Article L613-7 of the French Intellectual Property Code
Any person who, in good faith, at the date of filing or priority of a patent, was, in the territory where this Book is applicable, in possession of the invention which is the subject of the patent, shall have the right, in a personal capacity, to work the invention notwithstanding the existence of the patent. The right recognised by this Article may only be transferred together with the business, undertaking…