A patent is ineffective in regard of persons who had used the patented invention prior to the application or priority date (so-called “right of prior use”, see article of 06/08/2012 and, for designs, of 07/12/2017). However, this applies without limitation only to such embodiments of the invention which had been used before said date. How variants should be dealt with, is still an open issue.
This question is addressed by a recent decision “Schutzverkleidung” (“Protective cover”) of the German Federal Court of Justice (judgement of 14/05/2019, case No. X ZR 95/18). According to this judgment, a patent remains ineffective for variants which are self-evident or disclosed in the patent, however not associated with any advantage over the prior used embodiment. On the other hand, patent protection may apply in regard of such variants, which are emphasized as advantageous in the description or in a sub-claim.
This seems to indicate that patent applicants may, when drafting descriptions, influence in how far they can counteract such prior use rights later on: The more embodiments they disclose, associated with expressly mentioned advantages over the subject-matter of the main claim(s), the more effective the protection.
The judgment further clarifies that a person who had used the subject-matter of a patent not directly, but only indirectly, may nevertheless benefit from a right of prior use if such indirect use practically inevitably leads to a direct use. This addresses, in particular, the situation of a supplier of components who does not himself/herself assemble them to obtain a patented article. In these cases, a right of prior use may nevertheless arise for the supplier if such assembly is the only meaningful use of the components.