In a decision that is quickly gaining attention, the Federal Circuit held that the district court abused its discretion by excluding both of Plaintiff’s experts and subsequently granting Defendants’ judgment as a matter of law (JMOL) of no infringement. Barry v. DePuy Synthes Companies.

The ruling is notable given the Federal Circuit’s recent en banc decision in Google v. EcoFactor, which reinforced district court’s gatekeeping authority over expert testimony. In Barry, however, the Court seems to be shifting greater responsibility back to the jury to assess expert credibility and weight.

Background

Plaintiff sued several entities alleging they induced surgeons to infringe three of Plaintiff’s Patents (U.S. Nos. 7,670,358, 8,361,121, and 9,668,787) that relate to surgical techniques and tools for treating spinal deformities. The infringement dispute centered on claims in the ’358 and ’121 patents requiring certain tools to have one or more “handle means”.

After extensive claim construction briefing, the district court eventually adopted Plaintiff’s proposed construction, defining “handle means” as “a part that is designed especially to be grasped by the hand.” Op. at 3. Notably, the district court nevertheless acknowledged Defendants’ concern that this construction “could theoretically encompass every element of the accused products because in Defendants’ accused products, practically every part is grasped by hand.” Op. at 4. This critical tension drove the expert admissibility dispute.

During subsequent proceedings, Plaintiff relied on two experts—Dr. Yassir, who opined on infringement—and Dr. Neal, a survey expert who assessed how often the accused tools were used by surgeons in an infringing manner.

Initial Daubert motions to exclude both experts were denied, with the district court finding the arguments went to the weight of the experts’ opinions not their admissibility. Rather than outright exclude the experts, the court allowed Defendants to challenge the experts on cross-examination before the jury. Following cross-examination and additional briefing, the district court granted Defendants’ renewed motions.

As to Dr. Yassir, the court relied on testimony in which he appeared to equate “a part that is designed especially to be grasped by the hand”— with “parts that cannot be assembled without grasping them by hand.” Op. at 32. The court found that this reasoning extended the “especially designed” limitation to other aspects of the surgical tools merely because they had to be grasped during assembly.

With respect to Dr. Neal, the district court reversed its earlier ruling and found the survey unreliable based on alleged departures from accepted survey principles and an improperly defined universe of surgeons—criticisms it had previously deemed weight-based. Op. at 8, 28. Lacking admissible expert evidence on infringement, the court granted JMOL in Defendants’ favor.

Federal Circuit Reversal

The Federal Circuit reversed, holding that Dr. Yassir’s testimony reflected “an application of [the district court’s] construction that a reasonable factfinder could have accepted as persuasive or rejected as implausible.” Op. at 10. The panel emphasized testimony confirming Dr. Yassir applied the lower court’s claim construction language, and Defendants’ three (overruled) objections failed to assert Dr. Yassir contradicted the construction. Op. at 11. Because his testimony repeated the construction, demonstrating compliance, not contradiction, the jury should have been allowed to weigh the testimony as an application of the claim construction order.

The Court applied similar reasoning as to Dr. Neal’s survey. Because the district court ruled pre-trial that the alleged methodical defects went to weight, the Federal Circuit held it was an abuse of discretion to later deem the same defects so severe as to render the survey wholly inadmissible during trial—without explaining what had changed. The majority concluded that challenges to the survey should have been explored through cross-examination. The Federal Circuit reversed the JMOL because it was predicated on the lack of expert evidence.

Dissent

Judge Prost—who dissented in the original but later joined the majority in EcoFactor’s en banc decision—argued here in dissent that the majority applied the wrong standard of review. First, she reasoned, that the majority erred by sidestepping the EcoFactor approach, asking whether Dr. Yassir’s “application” of the claim construction was credible and belonging to the jury instead of addressing whether it was a permissible exclusion. Dissent Op. at 4-5. In her view, the question on appeal was not whether Dr. Yassir’s testimony was plausible to a jury, but whether the district court’s exclusion was “arbitrary, fanciful, or clearly unreasonable.” Id. at 5.

Examining the testimony, Judge Prost agreed with the district court that Dr. Yassir contradicted the claim construction order by equating “everything” in Figure 1 of the ’358 Patent as a “handle means”. If everything is a handle, she reasoned, then nothing is “designed especially to be grasped by the hand” as required by the claim construction. She also cited to testimony in which Dr. Yassir acknowledged that “certain parts of the accused surgical constructs ‘are not the places that you generally would want to grab,’ those parts, too, would be ‘handle means.’” Dissent Op. at 3-4. On that record, Judge Prost could not conclude the district court abused its discretion.

As to Dr. Neal and the survey, Judge Prost again argues that the majority improperly shifted the question of admissibility to one of weight and jury credibility. Dissent Op. at 9. She defended the district court’s questioning of the survey’s methodology as squarely within its gatekeeping function and faulted the majority for failing to explain how the district court’s ruling constituted an abuse of discretion. Id. at 11-12. 

Takeaways

Judge Prost’s dissent highlights a real concern. Barry may create an avenue for expert testimony to evade meaningful gatekeeping so long as the expert testifies they were applying the claim construction order in their opinions and frames disputed reasoning as an “application” of it. Under that approach, many admissibility issues risk being recharacterized as a question of weight, despite the recently amended Federal Rule of Evidence 702 which requires the proponent of evidence to “demonstrate[] to the court” it’s reliability.

Expert witnesses are supposed to assist the jury, ordinary laypeople, understand the legal and technical complexities that are modern patents. As Judge Prost writes: without this cornerstone ability to gatekeep unreliable and unhelpful opinions, the majority “contravenes the principles embraced in EcoFactor and the [F.R.E.] 2023 amendments, and …will undermine district court’s abilities to exercise its gatekeeping function. Dissent Op. at 2.

Whether Barry marks a broader retreat from EcoFactor remains to be seen. It is imperative, however, that litigants be more diligent than ever in their questioning and briefing. If future cases do signal a return to pre-EcoFactor thresholds, parties should expect reports to blur the line between expert opinion and legal advocacy.

For experts, Barry underscores the importance of precision and discipline in applying claim constructions and methodological frameworks. Even where courts ultimately defer admissibility to the jury, experts should take care to clearly articulate how their opinions track the court’s constructions without appearing to expand or redefine them in practice. Similarly, survey and technical experts should assume that methodological choices—such as universe selection, assumptions, and framing—will remain under sustained scrutiny, even if initially admitted. Barry does not eliminate the gatekeeping role of the district court; rather, it highlights that credibility, consistency, and transparent reasoning remain essential to ensuring expert testimony survives both admissibility challenges and appellate review.