According to Art. 81 (2) German Patent Act, an action for declaration of nullity of a German patent is inadmissible as long as an opposition against said patent may still be filed or opposition proceedings against the patent are pending. This regulation also applies to nullity actions directed against the German part of a European Patent (Art. 2 (2) European Patent Convention).

Generally speaking, Art. 81 (2) German Patent Act does not pose a significant problem to third parties, who are attacked on the basis of a European Patent falling under the scope of this procedural rule. Art. 105 European Patent Convention allows for such parties to participate in already pending opposition proceedings even after the expiry of the 9 months opposition deadline. However, problems can occur, if the scope of a German nullity action would be broader than that of the (already pending or still possible) opposition proceedings before the European Patent Office. For example, novelty issues based on national patent applications, which have been published on or after the publication date of the opposed European Patent, but which have an earlier priority date, cannot be taken into consideration by the European Patent Office. However, they would be comprised of the scope of a German nullity action.

In a judgment of April 19, 2011 (X ZR 124/10, “Mautberechnung”), the German Federal Supreme Court now found that Art. 81 (2) German Patent Act also applies in such specific situations of divergent scopes of (European) opposition proceedings and (German) nullity action. As long as the opposition proceedings are pending or the filing of an opposition is possible, a nullity action against the German part of the European patent is inadmissible, even if it is based solely on the argument of a lack of novelty deriving from prior German patent applications that have been published on or after the filing date of the European Patent.

However, as some kind of “remedy” for the potential infringer in such problematic situations, the Federal Supreme Court held that the court responsible for the parallel infringement action also has to take into consideration the chances of success of a nullity action as to be filed subsequently to the opposition proceedings when deciding on a suspension of the infringement action proceedings.