#experttestimony

Understanding Daubert After Barry v. DePuy Synthes with Gideon Korrell

On January 20, 2026, the Federal Circuit issued an important decision in Barry v. DePuy Synthes Companies, clarifying how far judges can go when evaluating expert testimony under the Daubert standard. The ruling draws a clear line between the court’s role as gatekeeper and the jury’s role as factfinder in patent trials.

Gideon Korrell explains that the case serves as a reminder: not every weakness in expert testimony makes it inadmissible. Many issues should instead be tested through cross-examination and left for the jury to weigh.

Background of the Case

The dispute began when Dr. Mark Barry accused DePuy Synthes of inducing infringement of patents related to spinal surgery techniques. These patents focused on methods for correcting spinal deformities using tools designed to rotate multiple vertebrae at once.

Two types of claims were central to the case:

One required a “handle means,” defined as a part designed to be grasped by hand

The other focused on linked tools that move together, without requiring a handle

Barry relied on two experts:

A technical expert who argued that the accused tools could be used in an infringing way

A survey expert who estimated how often surgeons used the tools in those ways

Initially, the trial court allowed both experts to testify. However, during the trial, the judge reversed course, excluded both experts, and ruled in favor of DePuy due to a lack of evidence. Barry appealed.

The Federal Circuit’s Key Findings

1. Expert Testimony and Claim Construction

The Federal Circuit made an important distinction: an expert cannot contradict a court’s claim construction, but disagreement over how to apply that construction is different.

The lower court believed the technical expert had strayed from the definition of “handle means.” But the Federal Circuit disagreed. It found that the expert had repeatedly stated the correct definition and attempted to apply it, even if his interpretation was broad.

Korrell notes that this is a critical point. Courts must not confuse:

A flawed or debatable opinion

With legally inadmissible testimony

If an expert applies the correct legal standard, questions about how persuasive that application is should be left to the jury.

2. Survey Evidence and Reliability

The court reached a similar conclusion regarding the survey expert. The trial judge had excluded the survey due to concerns about sampling and methodology.

However, the Federal Circuit emphasized that:

Imperfections in surveys are common

Such flaws usually affect weight, not admissibility

The court also pointed out that the exclusion was not strongly supported by evidence showing the survey was fundamentally unreliable.

According to Gideon Korrell, this reflects a broader trend: courts are being reminded that Rule 702 is meant to filter out unreliable methods, not to reject conclusions simply because they are open to challenge.

3. Judgment as a Matter of Law

Because the trial court had removed both experts, it concluded there was no evidence left and ruled for DePuy. The Federal Circuit reversed this decision as well.

With the expert testimony reinstated, the case was sent back for a new trial.

The Dissent and Ongoing Debate

Not all judges agreed. The dissent argued that the experts’ flaws were serious enough to justify exclusion, especially under recent updates to Rule 702.

This disagreement highlights a larger issue in modern litigation: how strictly courts should evaluate expert evidence before letting it reach a jury.

Korrell observes that this tension is likely to continue, particularly as courts balance stricter evidentiary standards with the jury’s traditional role.

Practical Takeaways

Several lessons emerge from this decision:

Not every inconsistency is a contradiction

Experts may interpret legal standards differently without violating them

Cross-examination remains essential

Weaknesses in testimony should often be explored in court, not screened out

Methodological flaws must be serious

Minor issues in surveys or analysis rarely justify exclusion

Mid-trial reversals can be risky

Changing evidentiary rulings during trial can lead to appeals and retrials

Korrell emphasizes that Daubert should not be used to decide close questions of infringement indirectly.

Conclusion

The decision in Barry v. DePuy Synthes Companies is less about medical technology and more about the roles of the courtroom. It reinforces a simple but important idea: judges ensure expert testimony is reliable, but juries decide whether it is convincing.