The US Court of Appeals for the Federal Circuit reversed jury verdicts of infringement, finding that they were not supported by substantial evidence because of deficiencies in the patent owner’s expert testimony. Finesse Wireless LLC v. AT&T Mobility LLC, Case No. 2025 WL 2713518 (Fed. Cir. Sept. 24, 2025) (Moore, C.J.; Linn, Cunningham, JJ.)

AT&T Mobility was accused of infringing two patents owned by Finesse Wireless, both directed to methods for mitigating intermodulation product interference in radios. The accused technology involved Nokia radios implementing passive intermodulation (PIM) cancellation. Nokia intervened in the case. A jury found all asserted claims valid and infringed, awarding Finesse more than $166 million in lump sum damages. AT&T and Nokia moved for judgment as a matter of law (JMOL) on both noninfringement and the damages award, and alternatively sought a new trial. The district court denied the motions. AT&T and Nokia appealed.

The Federal Circuit reversed the district court’s denial of JMOL on noninfringement and vacated the damages award, concluding that the jury verdicts were not supported by substantial evidence. The Court’s decision turned largely on shortcomings in the testimony of Finesse’s infringement expert, whose analysis was the sole basis for Finesse’s infringement case.

For the first patent, the Federal Circuit found that Finesse’s expert failed to demonstrate that Nokia’s PIM cancellation feature received all input signals required by the asserted claims. The expert relied on a Nokia diagram but misinterpreted it by mistakenly identifying a signal generated by the radio as one of the required input signals. Although the expert was made aware of the error, he did not clearly correct his position or identify alternative signals that satisfied the claim limitation. Finesse argued that the expert had corrected a “misimpression,” but the Court disagreed, finding that the expert failed to provide a clear and consistent explanation reconciling his contradictory positions.

The asserted claims of the second patent required seven multiplications involving three signals. Finesse’s expert relied solely on a Nokia document that listed only three multiplications yet equated them to the seven required by the claims. The Federal Circuit found this testimony inadequate, noting that the expert failed to explain how the three multiplications mapped to the seven required. On appeal, Finesse argued that the document actually evidenced 10 multiplications, but the Court was unpersuaded. Neither Finesse nor its expert explained how the 10 multiplications corresponded to the seven required multiplications, nor did they reconcile this new position with the expert’s prior reliance on only three multiplications.

Because Finesse failed to present expert testimony that adequately mapped each claim limitation to the accused method, the Federal Circuit reversed the jury’s infringement findings for both patents and vacated the damages award.

Practice note: The decision underscores the importance of detailed and consistent expert analysis in patent infringement cases, particularly when expert testimony is the sole basis for proving infringement.