Muhr und Bender v. Rassini Suspensiones: Federal Circuit Affirms Unpatentability
German automotive supplier Muhr und Bender KG failed to overturn an invalidity ruling on US9868330B2 — its leaf spring assembly patent — after the Federal Circuit issued a per curiam affirmance against Mexican suspension manufacturer Rassini Suspensiones. The appeal ran 577 days before closing on April 10, 2025.
Federal Circuit closes the door on Muhr und Bender’s leaf spring patent
Muhr und Bender KG, a German manufacturer known for precision metal components and spring systems, asserted US9868330B2 — a patent covering a leaf spring assembly designed for motor vehicles — against Rassini Suspensiones, S.A. de C.V., a Mexican-headquartered automotive suspension supplier. The underlying dispute centred on patentability, with Rassini mounting an invalidity/cancellation challenge that succeeded at the tribunal level and triggered this Federal Circuit appeal filed September 11, 2023.
The Federal Circuit, in a per curiam ruling issued April 10, 2025 by Chief Judge Moore and Circuit Judges Prost and Hughes, affirmed the finding of unpatentability. Affirmance at this level means the court found no reversible legal or factual error in the lower decision, leaving the patent cancelled. For Muhr und Bender, the ruling extinguishes enforceable rights in US9868330B2; for Rassini, it confirms freedom to operate in the contested leaf spring design space without licensing exposure.
The 577-day duration from filing to disposition is consistent with a fully briefed Federal Circuit appeal without oral argument, though the public record does not confirm whether argument was held. The per curiam form of the order — without a signed authored opinion — suggests the panel viewed the outcome as legally straightforward, leaving limited precedential footprint. What drove the original unpatentability finding, and whether prior art or claim construction was the decisive issue, is not disclosed in the available public record.
Filing to Unpatentable in 577 days
577 days from filing to Federal Circuit affirmance — above median for inter partes patent appeals
Federal Circuit affirms: what the unpatentability ruling means for both parties
Affirmance means the lower decision stands without modification
When the Federal Circuit affirms, it has reviewed the record and found no reversible error — whether legal or factual — in the tribunal below. The original unpatentability determination is now final at this court level. A per curiam order without a detailed opinion typically signals the panel considered the result legally clear-cut, providing minimal new guidance on the underlying patentability doctrine.
No reversible error foundUS9868330B2 is cancelled — Muhr und Bender loses enforceability
With affirmance, Muhr und Bender KG exhausts its Federal Circuit appellate avenue for this patent. US9868330B2 is unpatentable and cannot be enforced against any party. Further challenge would require a petition to the Supreme Court, which grants certiorari in only a small fraction of patent cases. The commercial exclusivity Muhr und Bender sought over its leaf spring assembly design is effectively extinguished in the US market.
Patent rights extinguishedRassini secures clear freedom to operate in US leaf spring design space
Rassini Suspensiones prevailed at both the tribunal level and on appeal, achieving cancellation of the asserted patent. The affirmance confirms Rassini — and by extension, the wider market — can design, manufacture, and sell leaf spring assemblies of the type claimed in US9868330B2 without US licensing obligations. The bar to reviving this patent through further appeal is extremely high, giving Rassini a durable competitive advantage in this specific design space.
FTO confirmed by Federal CircuitLeaf spring IP landscape opens for competitors post-affirmance
The cancellation of US9868330B2 removes a blocking patent from the automotive suspension sector. Competing manufacturers and Tier 1 suppliers working on leaf spring assemblies for light and commercial vehicles should note the cleared IP space, though related patents in the Muhr und Bender portfolio may still present exposure. The per curiam nature of the ruling limits its value as precedent, but the outcome itself is commercially significant for any player operating in vehicle suspension spring technology.
Cleared design space in suspension techFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Muhr und Bender, KG | Individual | German automotive spring and metal components manufacturer — holder of US9868330B2Search in Eureka ↗ |
| Defendant | RASSINI SUSPENSIONES, S.A. DE C.V. | Individual | Mexican automotive suspension manufacturer; successfully challenged patent validitySearch in Eureka ↗ |
| Plaintiff counsel | Frank A. Angileri | Attorney | Counsel for Muhr und Bender, KGSearch in Eureka ↗ |
| Plaintiff counsel | John P. Rondini | Attorney | Counsel for Muhr und Bender, KGSearch in Eureka ↗ |
| Plaintiff counsel | Kyle G. Konz | Attorney | Counsel for Muhr und Bender, KGSearch in Eureka ↗ |
| Plaintiff counsel | Marc Lorelli | Attorney | Counsel for Muhr und Bender, KGSearch in Eureka ↗ |
| Plaintiff law firm | Brooks Kushman PC | Law Firm | Representing Muhr und Bender, KGSearch in Eureka ↗ |
| Defendant counsel | John S. Artz | Attorney | Counsel for RASSINI SUSPENSIONES, S.A. DE C.V.Search in Eureka ↗ |
| Defendant counsel | Steven A. Caloiaro | Attorney | Counsel for RASSINI SUSPENSIONES, S.A. DE C.V.Search in Eureka ↗ |
| Defendant law firm | Dickinson Wright PLLC | Law Firm | Representing RASSINI SUSPENSIONES, S.A. DE C.V.Search 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 order — ‘ORDERED and ADJUDGED: AFFIRMED’ per curiam — is dispositive and unqualified. There is no remand, no partial reversal, and no modification of the underlying unpatentability finding. At the appellate level, the court applies a deferential standard to factual findings (substantial evidence) and de novo review to legal questions; affirmance across both standards confirms the lower tribunal’s analysis was sound. The brevity of the per curiam form suggests the panel found no debatable legal issue, leaving limited room for Muhr und Bender to construct a Supreme Court petition based on circuit split or novel legal question.
US9868330B2 — Leaf Spring Assembly for Motor Vehicles
US9868330B2, filed under application number US14/905840, protects a leaf spring assembly designed for use in motor vehicle suspension systems. Leaf springs are load-bearing elastic elements that absorb road shock and support vehicle weight, used widely in commercial vehicles, light trucks, and increasingly in passenger cars seeking weight reduction. The patent’s grant reflects a technical advance claimed in the design or composition of the assembly, likely relating to geometry, material layering, or end attachment — though the precise independent claims are not reproduced in the public case record.
For the automotive suspension sector, leaf spring patents represent meaningful commercial value: OEM supply contracts often specify proprietary spring geometries, and a valid blocking patent can create durable pricing power in Tier 1 supply chains. Muhr und Bender, as a leading European precision metal and spring manufacturer, would typically assert such a patent to protect market position in North American OEM programs. The cancellation of US9868330B2 removes this specific competitive barrier, but suspension suppliers should monitor Muhr und Bender’s broader granted and pending US portfolio for related claims that may cover adjacent spring assembly configurations.
Should your team run an FTO against US9868330B2 and related Muhr und Bender patents?
US9868330B2 is cancelled and poses no direct infringement risk. However, R&D teams and product engineers developing leaf spring assemblies, parabolic spring systems, or multi-leaf suspension components for passenger vehicles, light commercial vehicles, or trucks operating in the US market should assess the full Muhr und Bender patent estate. Residual granted patents and pending applications may cover closely related claim scope that was not at issue in this cancellation proceeding.
PatSnap Eureka’s FTO Search Agent enables your team to map the surviving Muhr und Bender US portfolio, identify claims that read on your specific spring assembly design, and benchmark against the prior art that invalidated US9868330B2. Eureka surfaces related family members, prosecution history insights, and competitor patent activity across the automotive suspension domain — giving procurement, R&D, and legal teams a consolidated risk picture before product launch or supply contract finalisation.
Run a freedom-to-operate analysis on US9868330B2 to assess your product’s exposure
Run FTO in Eureka →Related Federal Circuit appeals: automotive parts and suspension patent validity
Federal Circuit invalidity appeals involving automotive suspension and spring assembly patents — cases comparable to Muhr und Bender v. Rassini Suspensiones, Case 23-2373.
What this case signals for the automotive suspension IP landscape
A cancelled leaf spring patent at the Federal Circuit reshapes competitive dynamics for suspension suppliers and OEM procurement teams.
Per curiam affirmance sets a high bar for any future Muhr und Bender IP revival
A per curiam order without authored reasoning typically indicates the panel found no close legal question. This limits Muhr und Bender’s ability to distinguish the ruling in future proceedings or to use it as a springboard for related claims. Competitors and licensees should treat US9868330B2 as definitively cancelled.
Freedom-to-operate position for leaf spring suppliers is materially strengthened
With US9868330B2 cancelled, Tier 1 automotive suspension suppliers and OEM procurement teams sourcing leaf spring assemblies face reduced patent risk in this specific design space. R&D teams developing composite or steel leaf spring systems for passenger and commercial vehicles should nonetheless audit Muhr und Bender’s surviving US and international portfolio before finalising design choices.
KG v RASSINI — key questions answered
The Federal Circuit affirmed the unpatentability of US9868330B2 per curiam on April 10, 2025. The panel — Chief Judge Moore and Circuit Judges Prost and Hughes — found no reversible error in the lower decision, leaving the leaf spring assembly patent permanently cancelled and unenforceable.
A per curiam order without an authored opinion indicates the panel considered the outcome legally straightforward. For US9868330B2, it means the patent is cancelled without new legal reasoning that could be leveraged in related proceedings. The ruling has limited precedential value but is fully dispositive — the patent cannot be enforced in the United States.
The only remaining avenue is a petition for certiorari to the US Supreme Court, which accepts fewer than 5% of patent cases and rarely reviews straightforward unpatentability determinations. Absent a novel legal question or circuit conflict, the affirmance is effectively final. The patent is cancelled.
With US9868330B2 cancelled and the cancellation affirmed, manufacturers and suppliers of leaf spring assemblies for motor vehicles can design and supply products covered by the former claims without US infringement exposure from this patent. However, an FTO analysis against Muhr und Bender’s surviving US patent portfolio is advisable before drawing firm conclusions about related claim scope.
Muhr und Bender KG was represented by Brooks Kushman PC, with attorneys Frank A. Angileri, John P. Rondini, Kyle G. Konz, and Marc Lorelli on record. Rassini Suspensiones was represented by Dickinson Wright PLLC, with John S. Artz and Steven A. Caloiaro listed as counsel.
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