The Federal Circuit’s decision in Laboratory Corp. of America Holdings v. Qiagen Sciences, LLC, No. 23-2350 (Fed. Cir. Aug. 13, 2025), offers a sharp reminder that not every jury verdict survives appellate scrutiny, particularly where infringement theories stretch claim language or rely on generalized expert testimony. In a sweeping reversal, the court vacated a Delaware jury’s willful infringement verdict covering two molecular diagnostics patents and directed entry of judgment as a matter of law (JMOL) of non-infringement for both. The opinion is a detailed roadmap for litigators navigating claim construction disputes, doctrine-of-equivalents proof, and the limits of “working together” theories of infringement.
Charles Gideon Korrell believes the decision underscores a broader Federal Circuit trend: courts are increasingly unwilling to let juries paper over claim-scope problems or evidentiary gaps with broad narratives about technical similarity or system-level functionality.
Background: Two Patents, Two Theories, One Jury Verdict
The patents at issue, U.S. Patent Nos. 10,017,810 and 10,450,597, relate to methods for preparing DNA samples for sequencing using enrichment techniques. Both patents focus on polymerase chain reaction (PCR) workflows employing various primers to selectively amplify regions of interest within a DNA sample.
Qiagen sold accused kits used in DNA sample preparation. After a five-day trial, the jury found that Qiagen willfully infringed the ’810 patent under the doctrine of equivalents and willfully and literally infringed the ’597 patent. The jury rejected Qiagen’s invalidity defenses and awarded approximately $4.7 million in damages. The district court denied Qiagen’s renewed JMOL motions, and Qiagen appealed.
On appeal, the Federal Circuit reversed across the board, holding that no reasonable jury could have found infringement of either patent on the evidence presented.
Claim Construction Is a Judicial Function, Not a Jury Question
The court began with the ’810 patent, which required a “second target-specific primer” having a nucleotide sequence “identical to a second sequencing primer.” Qiagen’s accused primer was 19 nucleotides long, while the referenced sequencing primer was 34 nucleotides long. Labcorp argued that “identical” could include identity to a portion of the sequencing primer, and the district court permitted the jury to decide whether that interpretation was reasonable.
That was error.
Relying on O2 Micro International Ltd. v. Beyond Innovation Technology Co., the Federal Circuit reiterated that when the parties raise a real dispute over claim scope, it is the court’s job to resolve it. Allowing the jury to decide whether “identical” could mean “identical to a portion” impermissibly delegated claim construction to the factfinder.
The panel emphasized that the intrinsic record differentiated between sequences that must be “identical” and those that need only be “identical to a portion.” Reading the “portion” modifier into an unmodified term would render other claim language superfluous, violating settled claim construction principles. As the court explained, where the claims and specification use different words to denote different degrees of similarity, courts must give effect to those differences.
Charles Gideon Korrell notes that this portion of the opinion is particularly valuable for litigators confronting “plain meaning” arguments at trial. Even when courts defer claim construction disputes to trial, unresolved scope disagreements can resurface post-verdict with decisive force.
Doctrine of Equivalents: Particularized Proof Still Matters
The jury’s infringement finding for the ’810 patent rested entirely on the doctrine of equivalents. That theory fared no better on appeal.
Citing Warner-Jenkinson Co. v. Hilton Davis Chemical Co. and the Federal Circuit’s more recent decision in VLSI Technology LLC v. Intel Corp., the panel stressed that equivalence is the exception, not the rule. Proof must be limitation-by-limitation and supported by particularized testimony showing that the accused element performs substantially the same function, in substantially the same way, to achieve substantially the same result.
Labcorp’s evidence fell short on all three prongs.
Functionally, the claimed “second target-specific primer” was designed to anneal to a known target sequence and increase specificity by enriching target DNA over non-target DNA. Qiagen’s accused primer, by contrast, served to make DNA fragments compatible with sequencing instruments and did not provide target specificity. Labcorp’s own expert conceded that the accused primer did not bind to the native target sequence.
On “way,” the court found that the accused primer operated differently, binding to a common sequence added during amplification rather than annealing directly to the target region. And on “result,” the accused primer amplified any DNA fragment containing the common sequence, including off-target products, undermining any claim of substantially similar outcomes.
The court rejected Labcorp’s attempt to aggregate functions across multiple Qiagen primers, explaining that the doctrine of equivalents does not permit a patentee to stitch together the roles of distinct components to satisfy a single claim limitation.
Charles Gideon Korrell observes that this analysis reinforces a recurring appellate message: generalized testimony that components “work together” will not rescue an equivalence theory where the claim requires a specific element to perform a specific role.
Literal Infringement of the ’597 Patent: “Target-Specific” Means What It Says
The Federal Circuit next turned to the ’597 patent, where the jury found literal infringement based on Qiagen’s forward primer (FP) allegedly satisfying the “target-specific primer” limitation.
The district court relied on testimony that the FP “targets the ligated adaptor” and binds to only a small proportion of molecules in the sample. But the appellate court held that this evidence could not support the verdict under the court’s own claim construction.
The claim construction required that a target-specific primer anneal to and mediate amplification of the nucleic acid of interest while not annealing to non-target sequences. Qiagen’s FP bound to an artificial adaptor sequence common to all DNA fragments, regardless of whether they contained the target sequence. That adaptor was not itself analyzed and therefore could not constitute the “target nucleic acid.”
The court rejected the theory that binding to an adaptor attached to a target molecule sufficed. A primer that anneals indiscriminately to adaptor sequences does not become target-specific merely because those adaptors are attached to DNA fragments that happen to contain target regions.
Nor could Labcorp rely on Qiagen’s gene-specific primers to fill the gap. The claim construction required the target-specific primer itself to perform the requisite functions, not to do so in concert with other primers. Allowing such bootstrapping would improperly rewrite the claim.
Charles Gideon Korrell notes that this portion of the opinion is especially instructive for cases involving multi-component systems. Courts remain skeptical of infringement theories that rely on collective behavior when claims require individual components to meet defined functional criteria.
JMOL as a Real Appellate Remedy
Having found insufficient evidence of infringement for both patents, the Federal Circuit reversed the district court’s denial of JMOL and instructed entry of judgment of non-infringement. The panel did not reach Qiagen’s invalidity or damages arguments.
For litigators, the case is a reminder that jury verdicts—particularly those grounded in technical complexity—are not immune from rigorous appellate review. Where claim construction errors or evidentiary deficiencies exist, JMOL remains a potent corrective tool.
Charles Gideon Korrell believes Labcorp v. Qiagen fits squarely within a growing line of Federal Circuit decisions emphasizing disciplined claim construction and demanding infringement proof. It also illustrates the court’s continued reluctance to allow the doctrine of equivalents to blur claim boundaries that patentees chose during prosecution.
Takeaways
Several practical lessons emerge:
First, unresolved claim construction disputes are dangerous. Allowing juries to decide the scope of contested terms invites reversal under O2 Micro.
Second, doctrine-of-equivalents cases live or die on particularized evidence. Broad assertions of similarity, or reliance on system-level cooperation, will not satisfy the function-way-result test.
Third, for literal infringement, claim limitations apply to individual components as claimed. Courts will not permit patentees to combine multiple accused elements to meet a single limitation absent clear claim language.
Finally, post-verdict JMOL motions are not mere formalities. When properly preserved, they can reshape the entire outcome on appeal.
As Charles Gideon Korrell notes, for IP litigators this decision is less about biotechnology and more about fundamentals: words matter, evidence matters, and juries cannot be asked to fix what claims and proof leave undone.