IP Hot Topic: “Confusing and Unclear” Expert Testimony Results in Loss of $166.3 Million Jury Verdict

On Wednesday, September 24, the Federal Circuit set aside a $166.3 million patent infringement verdict in Finesse Wireless LLC v. AT&T Mobility LLC, 24-1039 (Fed. Cir. Sept. 24, 2025). The Court held that the jury’s verdict rested on “confusing and unclear” expert testimony and therefore lacked substantial evidence.

Finesse’s asserted patents, U.S. Patent Nos. 7,346,134 and 9,548,775, relate to mitigating intermodulation products (IMP), a type of interference affecting wireless signals. The focus of the appeal was testimony of Finesse’s expert witness, Dr. Jonathan Wells, which the Court found “self-contradictory.”

The ’134 patent claims a method for reducing IMP interference by oversampling a passband so it contains both the “signals of interest” and “interference generating signals,” and then canceling out the interference using a computer estimate of the IMPs. Dr. Wells’ testimony and accompanying expert report consistently identified the downlink transmit (DL(TX)) reference and the modeled PIM path of the accused Nokia devices as the “signals of interest” and “interference generating signals,” respectively. However, on cross examination, Dr. Wells agreed that Nokia’s modeled PIM path cannot be generated until after the sampling stage and therefore cannot map onto the “interference generating signals” required by the claims. Dr. Wells then “pivoted” and drew attention to two other input signals along the same path but stopped short of identifying them as the “signals of interest” or the “interference generating signals.” Despite his previous testimony agreeing it was impossible for the model PIM path to be generated in the sampling stage, Dr. Wells continued to identify it and the downlink transmit (DL(TX)) reference as mapping onto the ’134 patent claims. The Court concluded that this “confusing change of course” without a clear explanation for the inconsistency was insufficient to support the jury verdict.

The testimony regarding the ’775 patent was similarly marked by inconsistency. The ’775 patent claims were construed to require three “separately identifiable,” but not “unique” signals that are then digitally multiplied in seven specific multiplications to produce IMP cancellation signals. Only three multiplications were depicted in the Nokia technical document, but Dr. Wells equated them with the seven required by the ’775 claims without explanation. The Court determined that, without more explanation, no reasonable jury could find that the accused radios performed the seven claimed multiplications.

The Court thus held that judgment as a matter of law (JMOL) of non-infringement was proper as to both patents.

This decision provides a useful reminder of the importance of both (i) developing a tight and fully fleshed out infringement theory during discovery and (ii) properly preparing expert witnesses to provide clear and accurate testimony to the jury. In particular, potential gaps or difficulties in an infringement read should be identified as early in the case as possible so they can be resolved and dealt with as part of the patentee’s case-in-chief; the Finesse case demonstrates the serious consequences that can arise when such flaws are exposed for the first time upon cross-examination at trial.