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Federal Circuit Affirms Patent Invalidity, Emphasizes Need For Substantive Expert Testimony
08/26/2025On August 19, 2025, the U.S. Court of Appeals for the Federal Circuit issued an opinion affirming the U.S. District Court for the Eastern District of Louisiana’s grant of summary judgment that claims of Wilco Marsh Buggies & Draglines, Inc.’s (“Wilco”) amphibious vehicle patent are invalid as anticipated. Wilco Marsh Buggies & Draglines, Inc. v. Weeks Marine, Inc., C.A. No. 2023-2320 (Fed. Cir. Aug. 19, 2025).
In the district court, Wilco sued Weeks Marine, Inc. (“Weeks”) for patent infringement, asserting that Weeks’ amphibious excavators infringed several claims of U.S. Patent No. 6,918,801. Weeks moved for summary judgment of invalidity, arguing that the asserted claims were anticipated through “public use” and by “sales” of the MudMaster, a prior art machine manufactured by DredgeMasters International Inc. The district court adopted Wilco’s proposed construction of “chassis” as “[t]he supporting frame of a vehicle, exclusive of the body or housing,” and found that the MudMaster’s 16-foot connector pipes which extended through its support frame satisfied this limitation.
On appeal, Wilco argued that a genuine dispute of material fact existed as to whether the MudMaster included a chassis. Wilco relied on the testimony of its technical expert, Mr. Bennett, who opined that the MudMaster’s “ladder frame” was not a chassis and that the machine otherwise lacked a chassis. The Federal Circuit, however, found that Bennett’s opinion was conclusory and unsupported by meaningful analysis. The Court noted that, during a deposition, Bennett conceded that an amphibious vehicle must have a structure to support its pontoons and that beams could be “a portion of the chassis.” These admissions, the Court explained, undercut his assertion that the MudMaster lacked a chassis. And in fact, the Court found that Bennett’s testimony supported the conclusion that no reasonable jury could have found that the MudMaster lacked a chassis, as that term was construed by the lower court.
The Federal Circuit emphasized that a conclusory expert opinion cannot create a genuine dispute of material fact. The Court cited its precedent disfavoring unsupported expert assertions and determined that the record evidence—including assembly instructions, photographs, and expert testimony—unequivocally established that the MudMaster’s connector pipes formed a chassis. Because Wilco did not dispute that the MudMaster met the remaining claim limitations, the Federal Circuit affirmed the district court’s invalidity ruling based on the on-sale bar triggered by the prior art MudMaster sale.
