Barry v. DePuy Synthes Companies

Barry v. DePuy Synthes, decided January 20th, 2026. The Federal Circuit, in an opinion by Judge Stark, held that a district court abused its discretion when it excluded two of the patentee's experts in the middle of trial and then entered judgment as a matter of law against him. The court reversed and remanded for a new trial. Judge Prost dissented. Here's the brief.

Doctor Mark Barry sued DePuy Synthes in the Eastern District of Pennsylvania. He alleged that DePuy induced surgeons to infringe three of his patents — the '358, the '121, and the '787 — covering surgical techniques and tools for treating spinal deformities such as scoliosis. Surgeons place screws in the pedicles of the vertebrae, mount derotation tools on those screws, and apply force to bring the twisted bones back into alignment.

Barry offered two experts. Doctor Walid Yassir, a clinical professor of orthopedic surgery, gave the infringement opinion, which turned on a claim limitation the court had construed as a "handle means." Doctor David Neal, a survey expert, surveyed surgeons to determine how often they actually used the accused tools in an infringing way.

Before trial, DePuy moved to exclude both under Daubert. The district court denied those motions, reasoning that DePuy's real complaint went to the weight of Yassir's testimony, not its admissibility — though it described its pretrial rulings as tentative and offered to revisit them.

After Barry rested his case, DePuy renewed both motions. This time, while trial was still ongoing, Judge Diamond granted them in full. Having excluded both experts, he found Barry could not prove infringement, and granted DePuy judgment as a matter of law. Barry appealed.

The question was whether excluding that testimony was an abuse of discretion.

Because these are procedural questions, the court applied Third Circuit law, and reviewed the exclusions for abuse of discretion and the judgment as a matter of law de novo. The governing principle was not in dispute: an expert opinion that contradicts the court's claim construction is not helpful to the jury and should be excluded as unreliable under Rule 702. Rule 702, as amended in 2023, requires the proponent to demonstrate reliability to the court by a preponderance of the evidence, and the Federal Circuit has long held that no party may contradict the court's construction in front of a jury. The disagreement was therefore not about the rule. It was about whether Yassir had contradicted the construction, or simply applied it in a way DePuy disliked.

On the infringement expert, the court held the premise was wrong. Yassir had recited the court's construction to the jury and testified that he applied it. The answers DePuy pointed to had come in response to hypotheticals on cross-examination.

The remedy for that kind of dispute, the court said, was the adversary process — DePuy had in fact cross-examined Yassir, put on its own expert to criticize him, and elicited non-infringement testimony from three witnesses.

The court was careful about what the district court had done wrong. A judge may revisit a tentative pretrial ruling.

On the survey expert, the district court had faulted Neal for failing to define the survey universe, to conduct a probability survey, and to test for non-response bias. The Federal Circuit held that those criticisms rested on the district court's own reasoning rather than on evidence in the record, and were drawn largely from answers Neal gave to the judge's own questions at trial. That, the court held, did not on its own justify exclusion. In a footnote, the court added a caution: a judge who pursues a skeptical line of questioning about an expert's methodology should consider doing so outside the presence of the jury.

Judge Prost dissented. In her view the district court had properly excluded both experts, and the majority had converted every reliability question into a question of weight.

Both opinions claim EcoFactor. The majority reads it as preserving the line between admissibility and weight; the dissent reads it as a command to keep the gate. The Federal Circuit denied rehearing en banc, so the panel decision stands alongside EcoFactor rather than resolving the tension between them.

Barry v. DePuy Synthes Companies, 164 F.4th 896, decided January 20th, 2026. I'm John Goodhue. Thanks for watching.