Magnolia Medical Technologies, Inc. v. Kurin, Inc., Appeal No. 2024-2001 (Fed. Cir. Mar. 6, 2026)

Our Case of the Week touches on two claim construction issues – a post-jury-verdict “clarification” of a claim term by a judge, who overturned a jury verdict, and a determination whether the term “diverter” was subject to Section 112(f) as a “means-plus-function” term.

The patents in suit are directed to improved products for taking blood samples.  Historically, blood samples would get tainted with microbes on the skin that were dislodged and transferred into the sample through the needle.  This yielded false-positive results.  The invention improved upon this with a device that sequestered the first portion of the sample, and then separately stored the remainder of the sample.  One patent recited a fluid reservoir that had a “vent” and a “seal.”  A second patent recited a “diverter.”

The district court did not construe “vent” or “seal.”  With respect to “diverter,” the district court found it was subject to Section 112(f), and was thus limited to the structures disclosed in the specification.

Kurin’s accused product is called the “Kurin Lock.”  It does not have a “diverter” of the kind shown in the specification.  Accordingly, the district court granted non-infringement as to that patent.  With respect to the “vent” and “seal” limitations, the Kurin Lock uses a porous plug at the end of a chamber that serves both functions.  Specifically, when the porous plus is dry, air is able to vent out, and the chamber can fill with blood.  But when blood reaches the porous plug, the plug fills with fluid and seals, causing the blood in that chamber to fill up and overflow to a different channel, which can be captured.  The blood in the chamber is the initial sample, which can then be discarded, and the remainder is then kept as the sample.

At issue was whether the porous plug can qualify as both a vent and a seal.  The jury found infringement, but the district court granted JMOL, finding no infringement because a separate vent and seal were required.

Magnolia appealed both the JMOL finding on the vent/seal issue and the district court’s construction of “diverter.”

With respect to the vent/seal issue, the Federal Circuit found it was not error for the district court to grant JMOL.  First, it was not error to clarify this claim construction issue post jury verdict.  The Federal Circuit held that the district court’s decision merely “clarified” the plain ordinary meaning of the two claim terms, which was not improper in a JMOL setting.  Second, on the merits, the Court held that “vent” and “seal” had to be two separate structures based on the claim language.  The Court rejected a claim differentiation argument, holding that a dependent claim was not rendered superfluous by the reading of the two terms as being separate structures.  Magnolia also offered an alternative theory by which the jury may have found infringement, identifying a different device that satisfied the “vent” requirement, but the Federal Circuit rejected that approach because it was not presented to the jury.

With respect to the “diverter” claim, the Federal Circuit affirmed the district court’s finding that there was insufficient evidence of a sufficiently definite structure known in the art as a diverter.  The Court also affirmed that the term “diverter” was “a generic term that captures any structure that performs that function,” and thus was properly construed under Section 112(f).

Accordingly, the Court affirmed noninfringement with respect to both patents.

The full opinion can be found here.

By Nika Aldrich

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Exafer Ltd. v. Microsoft Corporation, Appeal No. 2024-2296 (Fed. Cir. Mar. 6, 2026)

On appeal from a grant of summary judgment in favor of defendant Microsoft, the Federal Circuit reversed the exclusion of expert damages testimony for patentee Exafer and remanded for further proceedings.  In holding the challenged testimony admissible, the reviewing panel clarified that in assessing a reasonable royalty, a patentee may permissibly rely on non-infringing aspects of the technology at issue to support inferences about the defendant’s valuation and use of accused features.

Here, Exafer asserted patents directed “to improving efficiency and optimization of data flows within virtual networks,” which Exafer contends are infringed by features of Microsoft’s Azure Platform.  To assess the value Microsoft placed on the accused features for purposes of a hypothetical negotiation, Exafer’s expert had relied on improvements in “virtual machine density” on Azure-associated CPUs.  Virtual machines themselves are not covered by Exafer’s patents, and relying on Enplas Display Device Corp. v. Seoul Semiconductor Co., 909 F.3d 398 (Fed. Cir. 2018), the district court excluded the expert’s testimony for including “activities that do not constitute patent infringement” in his estimated royalty base.  In reversing that decision, the Federal Circuit explained that “[a] reasonable royalty is not necessarily unreliable under Rule 702 because it uses a royalty base associated with an unaccused product.”  Because the expert’s opinions were based in evidence tying use of the accused features to increased virtual machine density—and demonstrating Microsoft’s valuation of the accused features on that basis—the Court deemed it “methodological[ly] sound” and held the lower court’s order excluding it to be an abuse of discretion.  Having reversed exclusion of the damages testimony, the Court vacated the resulting grant of summary judgment for lack of a remedy, and remanded.

The full opinion can be found here.

By Jason A. Wrubleski

This article summarizes aspects of the law and does not constitute legal advice. For legal advice with regard to your situation, you should contact an attorney.