Opinions — Tuesday, January 20, 2026

The Federal Circuit reversed the Eastern District of Pennsylvania's mid-trial exclusion of expert testimony and grant of judgment as a matter of law to defendants DePuy Synthes Sales, Inc. and related entities in this patent infringement action brought by Dr. Mark A. Barry concerning U.S. Patent Nos. 7,670,358, 8,361,121, and 9,668,787, which cover surgical techniques and tools for spinal deformity correction through "en bloc derotation." The court held that the district court abused its discretion under Federal Rule of Evidence 702 in excluding both Dr. Walid Yassir's infringement testimony and Dr. David Neal's survey evidence. With respect to Dr. Yassir, the Federal Circuit found that his testimony regarding the "handle means" limitation—construed by the district court as "a part that is designed especially to be grasped by the hand"—did not contradict the court's claim construction but rather applied it in a manner the jury could accept or reject, particularly where DePuy failed to object during direct examination despite a pretrial in limine ruling permitting exclusion of testimony inconsistent with the claim construction. As to Dr. Neal's survey, the Federal Circuit concluded the district court applied an improperly rigid reliability standard, faulting methodological choices that go to weight rather than admissibility under Third Circuit precedent.

The decision clarifies the boundary between expert testimony that contradicts a claim construction (and is therefore excludable as unhelpful under Rule 702) and testimony that applies a construction in a contestable manner (which is for the jury to assess). Judge Stark's majority opinion, joined by Judge Taranto, emphasizes that an expert's application of claim terms to accused products—even one that strikes the court as broad or implausible—does not become inadmissible merely because it arguably sweeps in more components than the district court anticipated when adopting the construction, particularly where the expert recites the construction and purports to apply it. The majority also reinforces that survey methodology criticisms typically affect weight, not admissibility, absent fundamental unreliability. Judge Prost dissented, arguing that Dr. Yassir's cross-examination testimony—including his statements that "everything is a handle means" in a linked system and that parts "cannot be assembled without grasping them by the hand" qualify as handle means—departed from the construction's "designed especially to be grasped" language and rendered his testimony internally contradictory and methodologically unreliable, warranting exclusion and affirming the judgment.