The Federal Court of Justice (ref. X ZR 180/18) had to decide in a nullity case whether a citation found by the plaintiff only during the appeal proceedings and introduced into the proceedings can still be taken into account.

The plaintiff had brought a nullity action against the patent in suit before the Federal Patent Court. At first instance, the patent proprietor and defendant had defended the patent in suit only in three restricted versions, but not to the extent granted. The Federal Patent Court then declared the patent in suit invalid to the extent no longer defended and dismissed the action in all other respects. The nullity plaintiff appealed against this decision.

In the appeal proceedings, the plaintiff had introduced citation D20 for the first time. The plaintiff had only become aware of this citation during the appeal proceedings by means of an official communication relating to the priority specification of the patent in suit. Prior to that, the plaintiff had carried out two searches which had not found citation D20. The first search had been carried out by the plaintiff after the defendant’s warning letter. However, the plaintiff could not comprehensibly explain the search criteria for this search. The second search had been carried out by the plaintiff after the statement of defence in the nullity proceedings. In the search, the plaintiff had combined classification F16D 55/*, to which the patent in suit is assigned, with the names of individual applicants or with search terms. The D20 did not contain these search terms and did not originate from any of the applicants combined with classification F16/D 55/* in the search. On the basis of the search terms, the plaintiff had found an application from an applicant who had not been included in the search until then and who was the applicant for D20. However, the plaintiff then did not extend its search to other applications filed by the applicant in class F16D 55/*. A search profile with the combination of the applicant and class F16D 55/* would have led to the D20 appearing in the search results.

The Federal Court of Justice dismissed the appeal. In doing so, the Federal Court of Justice did not consider citation D20. According to the decision, a citation that only came to the plaintiff’s attention in the second instance may only be taken into account pursuant to Sec. 117 (1) Patent Act and Sec. 531 (1) sentence 1 no. 3 Code of Civil Procedure if the plaintiff explains and, if necessary, substantiates why a search that would have brought the citation to light was not initiated in the first instance. The plaintiff must thus be able to explain how it created the search profile of the first instance search and why it chose such a profile. The Federal Court of Justice thus follows its previous case law (Federal Court of Justice, judgment of 27.08.2013 – X ZR 19/12 – Tretkurbeleinheit). As a result, the Federal Court of Justice considered it negligent not to extend the search in class F16D 55/* to the applicant of D20, although the plaintiff had already found a relevant citation from the applicant in this class. According to this, the plaintiff would not have found out about the D20 only by chance via the official communication, but would have found it at the latest with the second search.

For practice, this decision means that the hurdles are still high for successfully introducing a new citation into nullity proceedings only at the appeal instance. Primarily, the plaintiff should precisely define and record the search criteria of the search beforehand. If the plaintiff receives relevant indications in the course of the search that further relevant prior art might exist outside the search profile, the search profile should at least be reviewed and adjusted if necessary. Nullity plaintiffs should therefore also critically examine external searches to see whether they give rise to further indications that the plaintiff could pursue.