IP Law Daily, PATENT—Fed. Cir.: District court’s exclusion of expert testimony on spinal surgery medical devices reversed on appeal, (Jan 21, 2026)

By Carolin Dennis, B.Sc., LL.B., LL.M.

In a patent infringement suit involving spinal surgery medical devices, the district court abused its discretion by excluding expert testimony.

The U.S. Court of Appeals for the Federal Circuit reversed the district court’s decision finding it had abused its discretion in excluding the expert testimony regarding spinal surgery medical devices and erred in granting judgment as a matter of law (JMOL). The Federal Circuit remanded the matter for a new trial at which both Dr. Yassir and Dr. Neal may testify. Circuit Judge Prost filed a dissenting opinion (Barry v. Depuy Synthes Sales, Inc., No. 23-2226 (Fed. Cir. Jan. 20, 2026)).

Dr. Mark A. Barry sued DePuy Synthes Sales, Inc., Medical Device Business Services, Inc., and DePuy Synthes Products, Inc. (collectively, DePuy) in the United States District Court for the Eastern District of Pennsylvania alleging that DePuy induced surgeons to infringe certain claims of Barry’s U.S. Patent Nos. 7,670,358 (the ’358 patent), 8,361,121 (the ’121 patent), and 9,668,787 (the ’787 patent) (collectively, the Asserted Patents). Barry’s complaint alleged that DePuy manufactures derotation devices (Accused Tools) that, when used by surgeons in certain configurations, infringe the Asserted Patents. During discovery, Barry produced an expert report on infringement from Dr. Yassir, a clinical professor of orthopedic surgery. Dr. Yassir opined that the Accused Tools can be assembled and used in a manner that meets every limitation of the asserted claims and, in those instances, which he called infringing “constructs,” use of the Accused Tools infringes the Asserted Patents. Barry also produced an expert report from Dr. Neal, a survey expert. Dr. Neal, with assistance from Dr. Yassir, developed and administered a survey to determine whether and, if so, how often surgeons actually use DePuy’s Accused Tools in one of Dr. Yassir’s infringing constructs. At trial, DePuy moved to exclude two of Barry’s experts, Dr. Yassir and Dr. Neal.

The district court granted DePuy’s JMOL of no direct infringement, excluding Barry’s technical expert for failing to follow the district court’s claim construction and Barry’s survey expert for using an unreliable methodology.

Barry appealed, arguing that the district court abused its discretion by excluding the “handle means” portion of Dr. Yassir’s testimony and all of Dr. Neal’s testimony and survey. He further contended that the district court erred by granting DePuy judgment as a matter of law.

The Federal Circuit noted that the district court excluded the “handle means” portion of Dr. Yassir’s testimony pursuant to Federal Rule of Evidence 702 because it found this testimony “contradictory, unhelpful, and unreliable.” However, Dr. Yassir’s testimony did not contradict the court’s claim construction. It was, instead, an application of that construction that a reasonable factfinder could have either accepted as persuasive or rejected as implausible. The Federal Circuit found that Dr. Yassir did not contradict the court’s construction, either on direct or cross-examination. Therefore, the Federal Circuit determined that the district court’s finding to the contrary was clearly erroneous and, hence, its decision to exclude Yassir’s testimony on this basis was an abuse of discretion.

The Federal Circuit also noted that the many criticisms the district court had of Dr. Neal and his survey may persuade a reasonable jury not to place any substantial weight on his testimony, but they did not justify excluding it. The standards for admissibility and persuasiveness are not the same. Moreover, the district court failed to cite any actual evidence, either particularized or introduced at trial, to support its conclusion 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). Therefore, the district court abused its discretion in granting DePuy’s renewed motion to exclude Dr. Neal’s testimony.

The Federal Circuit also reversed the district court’s grant of JMOL, which was predicated on the lack of evidence remaining in the record after the district court excluded Dr. Yassir’s and Dr. Neal’s opinions.

Accordingly, the Federal Circuit concluded that the district court abused its discretion in excluding the expert testimony, erred in granting JMOL, and remanded the case for a new trial.

Judge Prost’s dissent. Circuit Judge Sharon Prost dissented and issued a separate opinion. According to her Dr. Yassir contradicted the court’s construction of “handle means,” and Dr. Neal prepared a survey having such numerous and significant flaws that the district court concluded it lacked reliability. She criticized the majority’s reliance for simply denoting these problems as issues of “fact” or “weight,” because it seriously undermined the district courts’ abilities to carry out their important gatekeeping responsibility. On the merits, Judge Prost would have affirmed. She concluded that the district court properly excluded Barry’s expert testimony because it was unreliable.

The Case is No. 23-2226.

Judge: Stark, L.

Attorneys: David Clay Holloway (Kilpatrick Townsend & Stockton LLP) for Mark A. Barry. Gregory A. Castanias (Jones Day) for Depuy Synthes Sales, Inc.

Companies: Depuy Synthes Sales, Inc.

Cases: Patent FedCirNews USPTO