An opposition filed against a patent based on the ground of a lack of practicability is admissible even if the opposition is based on a (partially) wrong interpretation of the claim wording, as long as this wrong interpretation is not arbitrary.
In the present case, the appellant had filed an opposition against the German patent DE 10 2006 004 232 based on the ground of a lack of practicability (Section 59 German Patent Act in connection with Section 21  No. 2 German Patent Act). Lack of practicability in this sense means that the patent is regarded not to disclose the invention in a manner sufficiently clear and complete for it to be carried out by the person skilled in the art.
The opposition was rejected by the German Patent and Trademark Office as being inadmissible for not fulfilling the formal requirements of an opposition (Section 59  Sentence 4 German Patent Act). The German Patent and Trademark Office argued that the ground for opposition is based on a misinterpretation of the claim wording and only due to this misinterpretation the alleged lack of practicability would arise.
Against this decision, the appellant filed an appeal with the German Federal Patent Court. In its decision of November 22, 2012, the German Federal Patent Court set aside the decision of the German Patent and Trademark Office and highlighted that an opposition is admissible even if it is based on partially wrong interpretations of the claim wording, as long as these wrong interpretations are not arbitrary and may even be suggested by the claim wording. Furthermore, the Federal Patent Court highlighted that, in order to fulfill the formal requirements of an opposition (Section 59  Sentence 4 German Patent Act), it would be sufficient to briefly outline the underlying facts, as long as the facts can be verified and proven by the German Patent and Trademark Office or the German Federal Patent Court, respectively. In detail, in the present case, the patent claims concerned a system for the sequential observing of different fluorescent materials. Thereby, for one mode of operation, a filter is used which blocks emissions in the infrared spectrum. However, one of the materials to be observed is emitting light in the infrared spectrum. Hence, with the filter blocking emissions in the infrared spectrum, an observation of this material would not be possible. This would give rise to the objection with regard to the lack of practicability – light which is blocked cannot be observed. Thereby, from the claim wording, it was not unambiguously clear that in the second mode of operation not the material emitting in the infrared spectrum, but another material shall be observed. The patent holder, however, was able to clarify this ambiguity based on the description, such that the patent was upheld in the amended version, eventually.
In the present case, the German Federal Patent Court highlights that the formal requirements for an opposition to be admissible are very low and are already fulfilled if the underlying facts are briefly outlined, as long as they can be verified and proven by the German Patent and Trademark Office or the German Federal Patent Court, respectively.
However, even though the requirements for the admissibility of an opposition are set low, the German Federal Patent Court makes it unmistakably clear that there is still the question of whether or not the objection raised is also reasoned. Nevertheless, the decision seems to soften the boundary between the valid ground for opposition of a lack of practicability and the not valid ground for opposition of a lack of clarity.
Therefore, “unclarity” may be a door opener for oppositions. Consequently, when claims are drafted, the claim wording has to be firmly checked as to not encompass features, which may be regarded to contradict each other, even if only unclear, in order not to open the door for an admissible opposition. Because once an opposition is admissible, there is always the risk for the patent holder that the opposition may also be successful and the patent is – in its entirety or at least partially – revoked.