On August 19, 2025, the Federal Circuit issued a non-precedential opinion affirming a Louisiana district court’s invalidation of U.S. Patent No. 6,918,801, owned by Wilco Marsh Buggies & Draglines, Inc. (“Wilco”), under the on-sale bar.
Background: Wilco’s Amphibious Excavator Patent
The ’801 patent covers a self-propelled amphibious vehicle for dredging and excavation. The design includes a chassis, pontoons for buoyancy, a track system for propulsion, and retractable spuds for stability.
Wilco filed suit in the U.S. District Court for the Eastern District of Louisiana, asserting that Weeks Marine, Inc.’s (“Weeks”) amphibious excavators infringed several claims of the ’801 patent. Weeks moved for summary judgment, arguing that the claims were anticipated by a prior art excavator known as the MudMaster, which had been sold in the early 1990s. Under 35 U.S.C. § 102, a product that is on sale more than one year before the filing of a patent application can bar patentability, a doctrine known as “on-sale bar.” Weeks argued that the MudMaster embodied each limitation of the asserted claims and therefore rendered them invalid.
District Court Applies the On-Sale Bar
The district court granted the motion for summary judgment, ruling the ‘801 patent claims as invalid under the on-sale bar. In its decision, the court adopted a construction of “chassis” as the supporting frame of a vehicle and held that the MudMaster’s 16-foot connector pipes extending through its support frame satisfied that definition.
Federal Circuit Affirms: MudMaster Anticipates Wilco’s Claims
On appeal, Wilco argued that factual disputes remained as to whether the MudMaster contained a chassis, relying heavily on its expert’s testimony. The expert opined that the MudMaster’s “ladder frame” was not a chassis and that the machine therefore lacked one entirely.
The Federal Circuit rejected this argument, explaining that conclusory expert opinions cannot create a genuine dispute of material fact. Additionally, the panel emphasized that the record evidence demonstrated that the MudMaster’s connector pipes functioned as a chassis under the court’s adopted construction.
Accordingly, the Federal Circuit affirmed, holding that the 1993 sale of the MudMaster anticipated the asserted claims and thus barred Wilco’s patent.