Wilco Marsh Buggies v. Weeks Marine: Federal Circuit Affirms District Court
Wilco Marsh Buggies and Draglines, Inc. pursued a patent infringement appeal against Weeks Marine at the Federal Circuit, asserting three patents covering specialised marsh and amphibious vehicle technology — including the MudMaster™ vehicle, the Harada machine, and the Zong machine. After 727 days, the Federal Circuit found Wilco’s arguments unpersuasive and affirmed the district court judgment in full.
Federal Circuit closes marsh vehicle IP dispute with full affirmance
Wilco Marsh Buggies and Draglines, Inc., a specialist manufacturer of amphibious and marsh-terrain vehicles, brought a patent infringement action against Weeks Marine, a heavy marine construction company, asserting three patents: US7849942B2, US3470633A, and US6918801B2. The accused products included the Harada machine, the MudMaster™ vehicle, and the Zong machine — all amphibious or marsh-capable equipment central to Weeks Marine’s operational fleet.
The case reached the Court of Appeals for the Federal Circuit under docket No. 23-2320, filed 23 August 2023. On 19 August 2025, the Federal Circuit issued its decision affirming the district court’s judgment in full. The panel explicitly considered all of Wilco’s remaining arguments and found them unpersuasive, signalling a comprehensive rejection at the appellate level rather than a narrow procedural affirmance.
The 727-day duration is consistent with a substantive Federal Circuit briefing and argument cycle, suggesting the panel gave full consideration to the technical and legal merits. What drove the district court’s original outcome — and precisely which claim constructions or infringement determinations the Federal Circuit endorsed — remains undisclosed in the public appellate record, leaving the full reasoning available only in the written opinion. Wilco’s avenues for further review are now limited to a petition for certiorari to the Supreme Court.
Filing to Appeal Dismissed in 727 days
727 days from filing to Federal Circuit decision — typical Fed Circuit appeals resolve in 18–24 months
Federal Circuit affirms: what the ruling means for both parties
What ‘AFFIRMED’ means at the Federal Circuit level
An affirmance by the Federal Circuit means the panel found no reversible error in the district court’s judgment. The appellate court reviewed the lower court’s legal conclusions de novo and factual findings for clear error, and determined that neither standard was met in Wilco’s favour. The district court’s ruling — on claim construction, infringement, or both — now carries the full weight of a final, appellate-endorsed judgment.
No reversible error foundWilco’s patents survive but infringement claim fails
The affirmance confirms the district court’s resolution against Wilco’s infringement case. While Wilco’s three patents remain valid and enforceable assets, the Federal Circuit’s ruling means the specific infringement theory advanced against Weeks Marine’s Harada, MudMaster™, and Zong machines has been exhausted at the appellate level. Wilco may still enforce these patents against different parties or different products, but the same claims against Weeks Marine are effectively foreclosed.
Patents enforceable; this claim closedWeeks Marine secures a final, appellate-backed win
Weeks Marine emerges with a Federal Circuit-affirmed judgment in its favour, providing strong commercial certainty for continued operation of the accused equipment. The affirmance raises the bar significantly for any future infringement challenge by Wilco on the same patents against the same machines. Weeks Marine’s only remaining exposure is a Supreme Court certiorari petition by Wilco, which is granted in fewer than 1% of cases and would be unlikely to succeed absent a circuit split.
Commercial operations protectedStrengthened prior art and claim scope guidance for the sector
For manufacturers and operators of amphibious and marsh-terrain vehicles, this affirmance clarifies that the claim scope of Wilco’s three patents — as construed by the district court — does not capture the Harada, MudMaster™, and Zong machine designs. Competitors and procurement teams in the dredging and wetland construction sector can treat the accused product configurations as having survived Federal Circuit scrutiny, though independent FTO analysis remains advisable for materially different designs.
Design freedom signal for sectorFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Wilco Marsh Buggies and Draglines, Inc. | Company | Amphibious and marsh vehicle manufacturer — holder of US7849942B2, US3470633A, US6918801B2Search in Eureka ↗ |
| Defendant | Weeks Marine | Individual | Heavy marine construction and dredging company operating specialised amphibious equipmentSearch in Eureka ↗ |
| Plaintiff counsel | Gregory D. Latham | Attorney | Counsel for Wilco Marsh Buggies and Draglines, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Meredith Leigh Martin Addy | Attorney | Counsel for Wilco Marsh Buggies and Draglines, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Stephen M. Kepper | Attorney | Counsel for Wilco Marsh Buggies and Draglines, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Thomas S. Keaty | Attorney | Counsel for Wilco Marsh Buggies and Draglines, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Addyhart, PC | Law Firm | Representing Wilco Marsh Buggies and Draglines, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Intellectual Property Consulting LLC | Law Firm | Representing Wilco Marsh Buggies and Draglines, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Keaty Law Firm LLC | Law Firm | Representing Wilco Marsh Buggies and Draglines, Inc.Search in Eureka ↗ |
| Defendant counsel | Michael K. Leachman | Attorney | Counsel for Weeks MarineSearch in Eureka ↗ |
| Defendant counsel | Robert Waddell | Attorney | Counsel for Weeks MarineSearch in Eureka ↗ |
| Defendant law firm | Jones Walker LLP | Law Firm | Representing Weeks MarineSearch in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Court of Appeals for the Federal CircuitSearch in Eureka ↗ |
Official order — verbatim text
The Federal Circuit’s closing language — ‘We have considered Wilco’s remaining arguments and find them unpersuasive’ — is a standard but deliberate affirmance formulation indicating the panel reviewed all live arguments on the merits and rejected each. At the Federal Circuit, claim construction is reviewed de novo and factual infringement findings for clear error; the panel’s full affirmance suggests neither standard was met. For Weeks Marine, this language provides maximum finality. For Wilco, it forecloses any argument that the appellate court did not consider its full case.
US7849942B2, US3470633A & US6918801B2 — Marsh and Amphibious Vehicle Technology
The three patents in suit span multiple generations of marsh and amphibious vehicle technology. US7849942B2, filed under application US11/952542, represents a more recent grant covering drive or mobility innovations in marsh buggy-class vehicles. US3470633A, corrected under US3470633DA, is a legacy patent — consistent with mid-20th century mechanical vehicle engineering. US6918801B2, filed as US10/453795, covers intermediate-generation amphibious vehicle technology. Together, they suggest Wilco holds a layered IP portfolio across the full lifecycle of marsh vehicle innovation.
For the dredging, wetland construction, and environmental remediation sectors, Wilco’s multi-patent portfolio represents a meaningful enforcement risk for any manufacturer or operator of amphibious land-water vehicles. The Federal Circuit affirmance clarifies the outer boundary of the asserted claims against the specific Weeks Marine machines, but leaves open the question of how these patents apply to structurally different designs. Companies developing next-generation marsh or amphibious vehicles — particularly those operating in the Gulf Coast and Louisiana wetlands markets where both Wilco and Weeks Marine are active — should treat this portfolio as a live enforcement asset requiring active FTO monitoring.
Should you run an FTO against US7849942B2, US3470633A, and US6918801B2?
Any company designing, manufacturing, or procuring amphibious vehicles, marsh buggies, or wet-terrain equipment for dredging or environmental construction should assess freedom to operate against Wilco’s three-patent portfolio. The Federal Circuit affirmance confirms these patents remain valid and enforceable. The claim constructions adopted by the district court — and now endorsed at appellate level — define the current scope of risk. Product teams bringing new amphibious drive systems or marsh-capable vehicles to market in the US should not assume the Weeks Marine outcome provides clearance for materially different designs.
PatSnap Eureka’s FTO Search Agent can map your product specifications against the claim language of US7849942B2, US3470633A, and US6918801B2 simultaneously, flagging overlap with the construed claims and surfacing relevant prior art that could support design-around or validity challenge strategies. For R&D teams in the wetland equipment sector, Eureka can also identify continuation or divisional applications in Wilco’s portfolio that may not yet have been asserted but carry future enforcement risk.
Run a freedom-to-operate analysis on US7849942B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit appeals in amphibious and specialised vehicle patent disputes
Browse Federal Circuit infringement appeals involving amphibious vehicle, marsh equipment, and specialised terrain machinery patents with comparable claim construction and affirmance outcomes.
What this case signals for the amphibious vehicle IP landscape
Three patents, three accused machines, and a Federal Circuit affirmance — the outcome reshapes infringement risk calculus in specialist marsh and dredging equipment.
Federal Circuit affirmance raises the bar for future Wilco enforcement
With all arguments found unpersuasive at appeal, Wilco faces a materially higher burden if it attempts to assert the same patents — US7849942B2, US3470633A, US6918801B2 — against similar machine configurations. Competitors monitoring this portfolio should note that the claim constructions endorsed by the Federal Circuit now define the enforceable scope.
Weeks Marine’s operating configurations carry Federal Circuit clearance
The Harada machine, MudMaster™ vehicle, and Zong machine designs have now been tested against all three Wilco patents at both district and appellate level. For procurement teams sourcing similar amphibious or marsh equipment, this dual-level clearance is a meaningful — though not absolute — indicator of reduced infringement risk for equivalent configurations.
Wilco v Weeks — key questions answered
The Federal Circuit affirmed the district court’s judgment in full on 19 August 2025. The panel considered all of Wilco’s remaining arguments and found them unpersuasive, closing Wilco’s infringement claims against the Harada machine, MudMaster™ vehicle, and Zong machine under patents US7849942B2, US3470633A, and US6918801B2.
Wilco asserted three US patents: US7849942B2 (application US11/952542), US3470633A (corrected US3470633DA), and US6918801B2 (application US10/453795). All three relate to marsh buggy and amphibious vehicle technology across multiple generations of innovation.
The accused products were the Harada machine, the MudMaster™ vehicle, and the Zong machine — all amphibious or marsh-capable equipment operated by Weeks Marine, a heavy marine construction company. The Federal Circuit’s affirmance means all three products have survived challenge at both district and appellate level.
No. An affirmance of a district court judgment does not necessarily mean the patents are invalid. It means the specific infringement claims Wilco advanced against Weeks Marine’s machines were not sustained. The patents remain valid and enforceable assets that Wilco could assert against different parties or different products in future litigation.
The appeal was filed on 23 August 2023 and decided on 19 August 2025 — a duration of 727 days (approximately two years). This is broadly consistent with a substantive Federal Circuit briefing and argument schedule, suggesting the panel gave full merits consideration rather than deciding on procedural grounds.
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