Asserting dependent claims in German patent infringement proceedings

Typically, in German patent infringement cases, the plaintiff only asserts one of the independent claims of the patent. In such a case, dependent claims are neither mentioned in the prayer for injunctive relief nor elsewhere in the plaintiff’s pleadings.

Having the broadest scope of protection, the asserted independent claim and an injunction based on it automatically covers embodiments in accordance with any of the dependent claims. Hence, there is generally no need for the plaintiff to assert dependent claims.

Such a need may arise, however, if the patent’s validity is or can be credibly challenged, and a stay of the case pending the outcome of German nullity or EPO opposition proceedings is likely. A plaintiff may therefore opt to assert a dependent claim already in the statement of claim or in its reply following the defendant’s invalidity arguments. By limiting the motions to a narrower, dependent claim, the plaintiff may be able to persuade the court that the additional feature(s) of the asserted dependent claim do establish novelty und inventiveness, thereby avoiding a stay.

In case of a reasonable non-infringement argument regarding the dependent claim, the plaintiff can and should assert the independent claim in the alternative to avoid a dismissal of the action. However, due to procedural reasons, the plaintiff cannot assert dependent claims in the alternative (in case the court would otherwise stay the case), but will have to decide – at the latest in the oral hearing – whether to assert the independent claim or a narrower, dependent claim. Hence, the plaintiff faces a trade-off between the chance to obtain a broad injunction and reducing the risk of a stay of the proceedings. In making this strategic decision, a plaintiff will be led by practical considerations as well as legal considerations, the most important of which will be addressed in the following:

Practical considerations:

• The attacked embodiments – will any of the attacked embodiments fall out of the scope of an injunction, if only a narrower, dependent claim is asserted? If not, asserting the dependent claim seems reasonable. If yes, the impact of the remaining scope of the injunction will have to be considered.
• A sign of weakness – asserting a dependent claim, already in the initial complaint or later as a reaction to the defendant’s invalidity arguments, might be interpreted as a sign of weakness by the court or the defendant. Are the validity arguments for the validity of the independent claim reasonable? If yes, asserting a dependent claim might needlessly weaken the case, especially if the features of the dependent claim do not clearly add value.

Legal considerations:

• Shifted burden of proof – generally, to obtain a stay, the defendant has to persuade the court that a revocation of the (independent claim of the) patent is very likely. If the plaintiff relies on a dependent claim, because the validity of the independent claim seems uncertain, the burden of proof shifts and the plaintiff has to persuade the court that the dependent claim is novel and inventive. The reason behind this shift in the burden of proof is that novelty and inventive step of the dependent claims are not independently examined by the patent offices. Therefore, it will have to be considered how straightforward the novelty argument for the dependent claim really is in case the independent claim is found invalid.
• Choice of venue – the major German patent infringement courts (Munich, Mannheim and Dusseldorf) do not apply exactly the same standard, when it comes to the assertion of dependent claims. While Mannheim is more hesitant to issue an injunction based on dependent claims once the independent claim lacks patentability – and will rather lean towards a stay –, Dusseldorf and Munich tend to be open for reasonable validity arguments in support of the dependent claim – and are more likely to issue an injunction based on dependent claims.
• Timing – the plaintiff will have to consider the appropriate timing for introducing the dependent claims into the proceedings. If an action is filed based on the independent claim, a later amendment of the prayers for relief will be admissible. However, if one of the attacked embodiments no longer falls under the narrower claim, the plaintiff risks a partial dismissal of the action and may have to bear the associated costs. In any case, in order to be sure to avoid a delay of the proceedings, the plaintiff should introduce the dependent claim in its reply at the latest.
• Respective auxiliary request in opposition or nullity proceedings – according to case law of the Federal Court of Justice, the plaintiff has to make sure that a patent claim corresponding with the scope of the requested injunction can also be maintained in nullity or opposition proceedings. Hence, the plaintiff will have to defend the patent with a request that covers the scope of the asserted dependent claim (e. g. by filing the dependent claim as an auxiliary request).

Finally, it is worth remembering that a defendant can only request a stay of the infringement proceedings, if the asserted patent and patent claim is in fact challenged in nullity or opposition proceedings (otherwise, the validity of the patent or patent claim is not at stake).

In a case before the Dusseldorf Court of Appeal, the defendant had filed a nullity action only against the asserted independent claim of the patent, although one of the dependent claims was equally infringed, but had not been mentioned in the infringement proceedings. Following a first instance injunction based on the independent claim and its revocation by the Federal Patent Court, the plaintiff limited the motions by only asserting the narrower, dependent claim on appeal. The defendant now had to file a second nullity action against the dependent claim in order to request a stay of the proceedings. Of course, in a case where infringement of the dependent claim (and the need to challenge its validity) is obvious, such a second nullity action may be considered late-filed and a stay may be denied for that reason alone. In the case at hand, the Dusseldorf Court of Appeal found negligence on part of both the defendant and the plaintiff (who should have mentioned the infringement of the dependent claim earlier in the proceedings), therefore considered a stay, but denied it based on a preliminary assessment of the merits of the second nullity action.