Precedential and Key Federal Circuit Opinions
1. GLOBAL TUBING LLC v. TENARIS COILED TUBES LLC [OPINION] (2023-1882, 2023-1883, 2/26/2026) (Taranto, Hughes, and Stark)
Stark, J. The Court vacated and remanded the district court’s grant of summary judgment that plaintiff committed inequitable conduct in obtaining U.S. Patent Nos. 9,803,256 (“’256 patent”), 10,378,074 (“’074 patent”), and 10,378,075 (“’075 patent”). On cross-appeal, the Court vacated and remanded the district court’s grant of summary judgment for plaintiff on defendant’s Walker Process fraud claim for attempted monopolization.
During prosecution, plaintiff did not submit to the PTO certain papers it had acquired (the “CYMAX documents”) that disclosed a carbon range overlapping with the lower end of the claimed range of the ’256 patent. In discussing the CYMAX documents with the prosecuting attorneys, the inventor stated in a draft declaration “I am not sure it is a good idea to disclose this document.” The inventor testified at his deposition that he did not believe the carbon ranges overlapped and that he believed another reference submitted to the PTO was cumulative of the CYMAX documents.
The Court determined that, taking the evidence in the light most favorable to plaintiff, a reasonable factfinder could find that the inventor was innocently mistaken about the lack of overlap and believed the documents were cumulative. The Court also found that the circumstances did not come within the “rare” Fifth Circuit exception,” where a judge in a bench trial has greater discretion to grant summary judgment, drawing inferences in favor of the moving party; the Court found that, in this case, the evidentiary facts were disputed and there were issues of witness credibility that precluded the application of the Fifth Circuit’s exception. The Court likewise rejected the argument that Federal Circuit caselaw permits a district court reviewing a motion for summary judgment of inequitable conduct to draw inferences against a nonmoving party.
The Court also held that the materiality of the CYMAX documents was another genuine dispute of material fact and that a reasonable factfinder could credit the testimony of the inventor explaining why the CYMAX documents are not but-for material to patentability in light of the disclosures in the references that were submitted.
On cross appeal, the Court found that the district court did not define the relevant market in terms of product or geography when concluding plaintiff was a small market player posing no dangerous probability of monopolizing the market. The Court further found there was a dispute of fact as to the proper date for measuring plaintiff’s market share. The Court also determined that a genuine dispute of material fact existed as to whether plaintiff engaged in predatory or anticompetitive conduct because a reasonable factfinder could find plaintiff threatened and intended to sue defendant on patents obtained by committing fraud on the PTO. Thus, the Court found plaintiff was not entitled to summary judgment on the Walker Process fraud claim.
2. MAGNOLIA MEDICAL TECHNOLOGIES, INC. v. KURIN, INC. [OPINION] (2024-2001) (3/6/2026) (Lourie, Hughes, Freeman, D.J.)
Lourie, J. The Court affirmed the district court’s judgment of noninfringement as to U.S. Patent No. 10,039,483 (the “’483 patent”) and its construction of claim 1 of U.S. Patent No. 9,855,001 (the “’001 patent”) as means-plus-function.
Affirming the district court’s judgment as a matter of law (JMOL) as to noninfringement of the ’483 patent, the Court rejected plaintiff’s arguments that (1) the district court’s claim construction of two limitations as needing to be met by separate structures was untimely; (2) if timely, the construction was correct; and (3) the jury had sufficient evidence to support its finding of infringement under the district court’s construction. First, the Court found that listing two limitations separately within a claim implies the claims’ plain and ordinary meaning requires separate structures for each limitation; thus, the district court only clarified what was inherent in the plain and ordinary meaning of the claim on JMOL and did not impermissibly adopt a materially different construction at JMOL. Second, the Court found the claim’s use of the “comprising … a” format, where each limitation had an “a” preceding it, requiring one or more of each structure. The Court also reasoned the separation of the limitations by the word “and” suggested one limitation was in addition to, i.e., separate from, the other. The Court concluded that the specification was consistent with the separate structures. Third, the Court determined that the plaintiff did not present at trial the theory it put forth on appeal to support the jury having sufficient evidence, and the Court therefore did not consider the argument.
The Court then addressed whether the district court erred in construing the term “diverter” in claim 1 of the ’001 patent as means-plus-function, which led the parties to stipulate to noninfringement before trial because it was undisputed that the accused device did not meet “diverter” under the means-plus-function construction. The Court found that claim 1 did not recite structure that performed the agreed-upon functionality of the “diverter,” which required the direction of fluid, because the recited structures operated passively by receiving and facilitating fluid. Plaintiff did not meaningfully dispute this interpretation and instead argued that two structures taken collectively were sufficient to perform the function because its expert opined that a POSA would understand a “diverter” to include those two structures. The Court found this instead confirmed that a “diverter” would not have sufficiently definite structural meaning, since the issue was whether additional structure was needed to direct the fluid. Thus, the Court affirmed the district court’s means-plus-function construction.
3. EXAFER LTD, v. MICROSOFT CORPORATION [OPINION] (2024-2296) (3/6/2026) (Moore, Taranto, Stoll)
Moore, C.J. The Court reversed the district court’s exclusion of plaintiff’s damages expert and vacated the district court’s orders denying plaintiff’s motion to reopen discovery and granting summary judgment based on absence of remedy.
The district court excluded plaintiff’s damages expert’s opinion for using non-infringing virtual machines as the royalty base, relying on Enplas Display Device Corp. v. Seoul Semiconductor Co., 909 F.3d 398 (Fed. Cir. 2018), in which the Court vacated a damages award that was based on activities that were not patent infringement. The Court disagreed that Enplas supported the district court’s exclusion of plaintiff’s damages expert, because in Enplas, the products the plaintiff had included in the royalty base had no causal connection to the accused products. The Court distinguished the case here, finding that defendant’s own documents demonstrated that the royalty base was based on the causal connection between the non-infringing virtual machines and the accused features, since the accused features allowed defendant to increase the number virtual machines it could host on its server. The Court determined that a reasonable royalty is not per se unreliable because it uses a royalty base associated with an unaccused product, and found the facts of the case, where the patent was directed to network optimization and efficiency improvements that allowed for the operation of more virtual machines, illustrated the expert’s methodology was sound. Thus, the Court found the district court abused its discretion in excluding the damages opinions. The Court then dismissed as moot plaintiff’s motion to reopen fact and expert discovery and vacated the grant of summary judgment based on absence of remedy, remanding for further proceedings.
4. IMPLICIT, LLC, v. SONOS, INC. [OPINION] (2020-1173, 2020-1174) (3/9/2026) (Taranto, Stoll, Cunningham)
Cunningham, J. The Court affirmed the Board’s decision holding that the certificates of correction of inventorship, which issued after the final written decisions had issued in the respective IPRs, had no impact on those final written decisions.
The Board had previously determined in final written decisions that a reference—Janevski—qualified as prior art and it also determined that the challenged claims were unpatentable in light of the Janevski reference. After those final written decisions, the patent owner petitioned the PTO to correct inventorship of the challenged patents; the PTO granted the petitions and issued the requested certificates of correction. The Board subsequently determined that, while 35 U.S.C. § 256 corrections typically have retroactive effect, judicial estoppel and waiver applied in the specific circumstances of this case and precluded patent owner from relying on the certificates of inventorship to revisit the final written decisions.
The Court held that (1) forfeiture can apply notwithstanding the retroactive effect of 35 U.S.C. § 256; and (2) the Board did not abuse its discretion in applying forfeiture in this case. First, the Court reasoned that it was proper to apply the principles requiring diligent action in seeking a correction of inventorship where a change in inventorship can directly affect the outcome of the proceeding. Second, the Court found that the Board did not abuse its discretion in finding forfeiture where patent owner failed to argue its inventorship theory before the Board, instead waiting until after final written decisions to seek certificates of correction. Unlike in Egenera, there was no mid-litigation change in claim construction that created a new issue as to an individual’s necessary presence as an inventor. The Court therefore found patent owner provided no adequate explanation as to why it could not have raised its inventorship argument earlier or why it did not more diligently seek correction.
