Finding that Expert Testimony “Aligns” with the District Court’s Claim Construction, the Federal Circuit “Backs” Its Admissibility

On January 20, 2026, the Federal Circuit (per Judge Stark and joined by Judge Taranto, with Judge Prost dissenting) reversed a decision from the Eastern District of Pennsylvania, excluding two experts who testified for plaintiff-patentee Dr. Mark A. Barry (“Barry”) and granting judgment as a matter of law in favor of Defendants DePuy Synthes Sales, Inc. et al. (“DePuy”), in the case Barry v. Depuy Synthes Co., No. 23-2226, 2026 U.S. App. LEXIS 1328 (Jan. 20, 2026). The Federal Circuit concluded that the District Court abused its discretion by excluding the expert testimony of Barry’s two experts.¹ In reversing the exclusion of the experts, the Court remanded the case for a new trial where both experts could testify.²

The three patents in suit concern surgical techniques and tools for treating spinal deformities, such as scoliosis, that cause vertebrae to twist out of alignment.  During procedures to correct such conditions, screws are placed in the vertebrae and are manipulated via derotation tools, thus allowing an orthopedic surgeon to apply force to the vertebrae to realign the spinal column.³

Two of the patents require the use of “handle means”, a term was that hotly contested in the District Court.  Before trial, the District Court adopted Barry’s proposed construction of the term, defining it as “a part that is designed especially to be grasped by the hand.”⁴

Plaintiff relied on the expert testimony of its two experts: Dr. Walid Yassir and Dr. David Neal.⁵  Dr. Yassir provided testimony that DePuy’s accused tools met every limitation of the asserted claims.⁶  Dr. Neal developed and administered a survey which determined whether and how often surgeons actually use DePuy’s tools in the infringing manners that Dr. Yassir described.⁷

Prior to trial, the District Court denied DePuy’s Daubert motions seeking to exclude portions of both Dr. Yassir and Dr. Neal’s testimony.⁸  With respect to Dr. Yassir’s testimony, the Court held—in response to DePuy’s argument that Dr. Yassir’s analysis contradicted the District Court’s claim construction of “handle means”—that DePuy’s argument was focused on Dr. Yassir’s conclusions, which are not the subject of Daubert motions, and those arguments go to Dr. Yassir’s credibility, not admissibility.⁹  Regarding Dr. Neal, the District Court explained that criticism regarding the format of a survey goes to the weight of the evidence, not admissibility.¹⁰

At trial, Barry rested his case after Drs. Yassir and Neal testified.  DePuy then renewed its motion to exclude the testimony of the two experts, and also moved for judgment as a matter of law under Federal Rule of Civil Procedure 50(a).  The District Court granted both motions and entered judgment in DePuy’s favor without submitting the case to the jury.¹¹  The District Court explained that Dr. Yassir’s testimony was inadmissible because it “varied from and contradicted” the District Court’s construction of “handle means”, thereby rendering it improper and unhelpful to the jury as trier of fact.¹²  Also, Dr. Neal’s survey methodology was found not to meet the standards of reliability under Daubert, Federal Rule of Evidence 702(a) and Federal Rule of Evidence 403.¹³

The Federal Circuit reviewed the District Court’s judgment using the law of the regional circuit (here, the Third Circuit) to address the issues presented, because the issues did not implicate questions unique to patent law.¹⁴ Under Third Circuit law, rulings on motions to exclude evidence are reviewed for abuse of discretion.¹⁵  The Third Circuit reviews rulings on motions for judgment as a matter of law de novo.¹⁶

The Federal Circuit held, contrary to the District Court, that Dr. Yassir’s testimony did not contradict the court’s claim construction.¹⁷  Rather, the testimony was an application of that construction that a reasonable factfinder could either accept as persuasive or reject as implausible.¹⁸  The Court emphasized that questions of credibility and disputes as to the probative value of an expert’s application of the court’s claim construction are matters for the jury, not the court.¹⁹  Accordingly, the Federal Circuit concluded that the District Court should have allowed Dr. Yassir’s testimony.²⁰

The Court went on to distinguish this case from Barry v. Medtronic, 230 F.Supp. 3d 643 (E.D. Tex. 2017).²¹  In Barry v. Medtronic, the district court excluded the expert’s opinion who opined that an accused produced lacked a mechanical link because the alleged link was a screw, even though the court had explicitly stated in its claim construction order that a screw could constitute a mechanical linkage.²²  This was a clear contradiction that had to be excluded.²³

In sum, the Federal Circuit concluded that as per Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579, 596 (1993), vigorous cross examination, presentation of contrary evidence and careful instruction on the burden of proof—rather than exclusion—are the traditional and appropriate means of attacking shaky but admissible evidence.²⁴  Under that standard, the Federal Circuit concluded that DePuy could have used non-infringement experts to criticize Dr. Yassir’s testimony or used other witnesses to elicit testimony regarding the accused products.²⁵  The District Court, however, was found to have abused its discretion in excluding Dr. Yassir’s testimony.²⁶

The Federal Circuit also held that Dr. Neal’s testimony was admissible because the methodology and any flaws in the methodology for conducting the survey went to the weight of the evidence, and not its credibility.²⁷  The Court explained that the many criticisms the District Court had regarding the survey may well have persuaded a reasonable jury not to place substantial weight on the testimony; but, that did not justify excluding the entire testimony.²⁸  Further, the Federal Circuit faulted the District Court for failing to cite any actual evidence to support its conclusions that the flaws it found in Dr. Neal’s survey, methods, and opinions render his testimony unhelpful to the trier of fact under Rule 702(a) or inadmissible under Rule 104(a).²⁹

The Federal Court reversed the judgment as a matter of law (JMOL), and ordered a new trial.³⁰  The District Court’s grant of JMOL was predicated on the lack of evidence remaining on the record after the District Court excluded Dr. Yassir and Dr. Neal’s testimonies.³¹

Judge Prost dissented.³² In Judge Prost’s view, the District Court was proper in excluding the testimony of both experts. Dr. Yassir’s testimony contradicted the court’s claim construction, and Dr. Neal’s testimony was riddled with methodological flaws.³³  Citing the recent en banc decision in EcoFactor, Inc. v. Google LLC, 137 F.4th 1333, 1340 (Fed. Cir. 2025) and the recent amendments to the Federal Rules of Evidence, Judge Prost emphasized how the proponent of evidence must demonstrate to the court the reliability of evidence.³⁴  Further, the Advisory Committee criticizes district courts for treating questions of sufficiency of an expert’s basis and the application of methodology as a question of weight and not admissibility.³⁵  Judge Prost viewed the contradiction of Dr. Yassir’s testimony and Dr. Neal’s methodological flaws as questions of admissibility; not as issues of fact or weight for the jury.³⁶

Although the decision in this case finds that the jury should have been permitted to weigh the challenged expert testimony, litigants should not assume that this decision foreshadows a more permissive approach to admissibility going forward. Effective December 1, 2023, the Advisory Committee for the Federal Rules of Evidence made two amendments to Rule 702 to clarify the court’s rule regarding admissibility of evidence.³⁷  The first amendment emphasized that “expert testimony may not be admitted unless the proponent demonstrates to the court.. that the proffered testimony meets the admissibility requirements.”³⁸  According to the Committee, courts have been incorrectly applying Rule 702 by allowing critical questions of sufficiency of an expert’s opinion and methodology to go to the weight of the evidence, rather than admissibility.³⁹

The District Court’s rulings in this case were made before these amendments took effect.⁴⁰  Therefore, although the Federal Circuit’s majority opinion does not say so expressly, the opinion is likely best understood as applying Third Circuit law as it stood prior to the 2023 amendments to Rule 702.  Although it is entirely possible that the Federal Circuit ultimately would have found the challenged testimony of Drs. Yassir and Neal to be admissible even under the 2023 amendments to Rule 702, an analysis under the amended version would likely look a bit different.  In the case of Dr. Yassir, the 2023 amendment would likely require a court not only to determine whether the testimony was an application of the District Court’s claim construction, but also whether a preponderance of the evidence establishes that the testimony reflects a reliable application of his principles and methods to the facts of the case.  In the case of Dr. Neal, the amended version of Rule 702 would require, among other things, that the court determine whether a preponderance of the evidence establishes that the survey was based on sufficient facts or data.  Under the earlier version of Rule 702, many courts considered such questions to go to the weight of the expert’s testimony rather than to admissibility.  The amended version of Rule 702 makes clear that these questions go to admissibility.  Again, it is possible that this particular case would have come out the same way under either version of Rule 702.  However, future litigants can reasonably expect district courts to subject proposed expert testimony to more rigorous scrutiny before admitting such testimony.