The Federal Circuit recently found that a district court abused its discretion when it struck portions of a patentee’s expert infringement report as allegedly including an infringement theory absent from the plaintiff’s contentions. The district court found that the patentee’s infringement contentions identified “where” a claim limitation was found but failed to explain “how” the identified components satisfied the claim limitation. In Taction Tech., Inc. v. Apple Inc., Appeal No. 2023-2349 (Fed. Cir. Aug. 13, 2025) (nonprecedential), the Federal Circuit reversed. The Federal Circuit held that the additional “how” requirement imposed by the district court was unsupported by the court’s local patent rules, which require only an identification of “where” each element of each asserted claims is found within each accused product.
Procedural Background
The Taction appeal arrived at the Federal Circuit after the district court (the United States District Court for the Southern District of California) granted summary judgment of noninfringement. In its order granting summary judgment, the court struck certain portions of the infringement report of Taction’s expert as improperly including an infringement theory absent from plaintiff’s infringement contentions. In those infringement contentions, Taction identified Taptic Engines in Apple’s accused products as satisfying a “highly damped output” claim requirement. Taction also referenced certain graphs in its contentions, and, in those graphs, Taction asserted that “ferrofluid” reduces a mechanical resonance. Taction’s expert identified those same two components—the Taptic Engines and ferrofluid—as satisfying the “highly damped output” requirement and further explained how those components did so. The district court found this additional “how” explanation as impermissibly exceeding the scope of Taction’s contentions. Taction argued that its contentions complied with the court’s patent local rules which require, as party of infringement contentions, “[a] chart identifying specifically where each element of each asserted claim is found within each Accused Instrumentality.” The district court disagreed, holding that Taction was required to explain how the identified components satisfied the claim requirements. The district court thus struck the portions of the expert’s report that provided the “how” explanation missing from Taction’s contentions.
The Federal Circuit vacated the district court’s order. The appeals court found that the district court abused its discretion in applying the patent local rules. In relevant part, the Federal Circuit found the district court’s interpretation of the patent local rules “as including an unwritten ‘how’ requirement was arbitrary and improperly reads in a requirement that has no support in the plain language of the rule.” The Federal Circuit contrasted the local rules from the Southern District of California with the local rules from the Northern District of California, which require the charts specify “where and how” the elements are found. The Federal Circuit noted that a district court may add requirements beyond those found in the local rules; however, the district court had not done so in this instance. Thus, “the parties were not on notice of the requirement and did not have an opportunity to comply.”
Conclusion
Although the Taction opinion is nonprecedential, patentees nevertheless can be expected to cite to it in defense of an expert’s infringement report that arguably exceeds its contentions. Specifically, in jurisdictions whose patent local rules are similar to those of the Southern District of California, patentees will argue that the requirement for infringement contention claim charts to specify the “where” of infringement do not require the “where and how.” There are numerous such districts, including, for example, the following: Eastern District of Texas, District of New Jersey, Middle District of North Carolina, and Northern District of Georgia. On the other hand, defendants in those jurisdictions may propound interrogatories seeking the “how” of the patentee’s infringement theories during fact discovery and may argue that such interrogatories are not redundant of the applicable patent local rules for the same reason.