Kuster & Western Digital v. USPTO: Federal Circuit Affirms Patent Cancellation
Martin Kuster, Western Digital Corporation, Western Digital Technologies, and SanDisk LLC jointly appealed USPTO invalidity rulings on two external storage device patents. The Federal Circuit affirmed the cancellations in full, closing a 637-day appellate proceeding that extinguishes both US8705243 and US8693206.
Federal Circuit confirms cancellation of two Western Digital storage patents
Filed on 14 April 2022, Appeal No. 22-1644 was heard before the Court of Appeals for the Federal Circuit. The appellants — inventor Martin Kuster alongside Western Digital Corporation, Western Digital Technologies, Inc., and SanDisk LLC — challenged USPTO invalidity or cancellation determinations directed at two patents: US8705243 and US8693206, both covering external storage device technology. Kilpatrick Townsend & Stockton LLP represented the appellants throughout.
The Federal Circuit issued an affirmance, upholding the USPTO’s patentability findings against both asserted patents. The appeal was ultimately recorded as dismissed, consistent with the court confirming the lower tribunal’s invalidity or cancellation rulings. An affirmance at the Federal Circuit level leaves the patents unenforceable, removing them from Western Digital’s and SanDisk’s assertable portfolio without further avenue for reinstatement at this stage.
The 637-day duration is broadly consistent with Federal Circuit appeal timelines for inter partes or post-grant review affirmances. The joint participation of the corporate entities alongside the individual inventor suggests the patents had been assigned or exclusively licensed within the Western Digital/SanDisk family prior to the appeal. The public record does not disclose settlement terms, licensing positions, or whether continuation applications covering related subject matter remain pending.
Filing to dismissal in 637 days
637 days from filing to Federal Circuit decision
Federal Circuit affirmed: both storage patents cancelled
What ‘Affirmed’ means at the Federal Circuit
An affirmance by the Court of Appeals for the Federal Circuit means the appellate panel found no reversible error in the USPTO’s patentability determination. The lower tribunal’s cancellation or invalidity ruling stands in full. For appellants, this exhausts the primary appellate route — further review would require a petition to the US Supreme Court, which is rarely granted in patent validity disputes.
Appellate affirmanceBoth US8705243 and US8693206 are now cancelled
Following affirmance, US8705243 and US8693206 lose enforceability. Any pending or threatened infringement claims relying solely on these patents are extinguished. Competitors and product teams previously monitoring these patents for FTO exposure can treat them as no longer presenting claim risk — though related continuation or divisional patents in the same family warrant independent review.
Patents cancelledWestern Digital and SanDisk lose two external storage IP assets
The joint appellate stance of Western Digital Corporation, Western Digital Technologies, and SanDisk LLC signals these patents were commercially significant enough to defend through full Federal Circuit appeal. Losing both suggests the relevant claim scope covering the external storage device architecture could not withstand prior art scrutiny. Companies competing in the portable and external flash storage segment should monitor the broader patent family for surviving related claims.
Corporate IP lossCancellation via USPTO — not district court invalidity
The verdict cause is recorded as an Invalidity/Cancellation Action originating at the USPTO, consistent with an inter partes review (IPR) or post-grant review (PGR) proceeding appealed to the Federal Circuit. This route — rather than district court invalidity — typically indicates a third-party petitioner challenged the patents at the Patent Trial and Appeal Board. The petitioner’s identity is not disclosed in this public record summary.
USPTO post-grant reviewFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Martin Kuster | Company | Inventor and storage IP holder — co-owner of US8705243 and US8693206Search in Eureka ↗ |
| Defendant | Defendant | Company | No defendant identified in the public record — appeal against USPTO rulingSearch in Eureka ↗ |
| Plaintiff counsel | Andrew N. Saul | Attorney | Counsel for Martin KusterSearch in Eureka ↗ |
| Plaintiff counsel | David A. Reed | Attorney | Counsel for Martin KusterSearch in Eureka ↗ |
| Plaintiff counsel | Frederick Lee Whitmer | Attorney | Counsel for Martin KusterSearch in Eureka ↗ |
| Plaintiff counsel | Russell Korn | Attorney | Counsel for Martin KusterSearch in Eureka ↗ |
| Presiding judge | Judge / | Chief Judge | Court of Appeals for the Federal Circuit — Chief JudgeSearch in Eureka ↗ |
Stipulation of dismissal — official text
The single-word verdict ‘AFFIRMED’ confirms the Federal Circuit panel found no reversible error in the USPTO’s cancellation of US8705243 and US8693206. For Western Digital and SanDisk, affirmance forecloses reinstatement of these patents through this appellate chain. For the market, both patents are unenforceable. The absence of a remand or partial reversal indicates the appellants’ arguments on validity — whether directed to claim construction, prior art scope, or procedure — were rejected in their entirety.
US8705243 & US8693206 — External Storage Device Architecture
US8705243 (application no. US13/362431) and US8693206 (application no. US13/757505) are utility patents directed to external storage device technology, consistent with portable flash memory or USB/SSD-type storage architectures. Both patents list Martin Kuster as inventor and were held within the Western Digital and SanDisk corporate family, suggesting they cover commercially deployed product features. The sequential application numbers indicate the patents were filed and prosecuted within a relatively narrow window, suggesting a coordinated filing strategy around a common technical concept.
External storage device patents of this type typically protect data management, controller logic, interface protocols, or physical packaging innovations in portable flash memory. Western Digital’s acquisition of SanDisk made the combined entity one of the world’s largest holders of NAND flash IP. The decision to appeal USPTO cancellation through the Federal Circuit signals that the patent holder considered these claims commercially material — making their cancellation a meaningful shift in the competitive IP landscape for anyone active in external storage, portable SSDs, or USB flash products.
Should you run an FTO against US8705243 and US8693206?
For product teams developing external storage devices, portable SSDs, or USB flash products, the cancellation of US8705243 and US8693206 removes the direct infringement risk these patents posed. However, FTO due diligence should not stop here. Western Digital and SanDisk hold extensive continuation families in flash memory and storage controller technology, and related claims covering the same underlying architecture may persist in sibling applications. Any product entering this space warrants a full family-level FTO review.
PatSnap Eureka’s FTO Search Agent can map the complete patent families surrounding US8705243 and US8693206 — identifying continuation applications, divisional filings, and claims with overlapping technical scope that survived the cancellation. Eureka’s claim monitoring tools allow R&D and IP teams to track new publications in the Western Digital and SanDisk portfolios as prosecution continues, ensuring no rebuilt coverage re-enters the landscape undetected.
Run a freedom-to-operate analysis on US8705243 to assess your product’s exposure
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What this ruling signals for the flash storage IP landscape
Two cancelled Western Digital storage patents and a Federal Circuit affirmance reshape competitive risk exposure in the external flash storage segment.
External storage IP is under active validity pressure at the USPTO
The successful cancellation of both US8705243 and US8693206 via USPTO proceedings — surviving through Federal Circuit appeal — suggests post-grant review is proving effective against flash storage patents. Companies holding similar external storage patents should proactively audit claim defensibility. Companies facing assertions should consider IPR as a primary defence strategy.
FTO exposure on these two patents is now resolved — but the family is not
With both patents cancelled, the immediate FTO risk they represented is extinguished. However, Western Digital’s and SanDisk’s broader patent portfolios in flash memory and external storage remain substantial. R&D teams and product counsel should verify whether continuation or divisional applications claim overlapping subject matter before treating the space as clear.
Martin v Defendant — key questions answered
The Federal Circuit affirmed the USPTO’s cancellation of US8705243 and US8693206 in Appeal No. 22-1644. Martin Kuster and Western Digital/SanDisk entities jointly appealed the invalidity rulings; the court upheld them in full on 11 January 2024, closing the case after 637 days.
No. Following the Federal Circuit’s affirmance of their cancellation, US8705243 and US8693206 are no longer enforceable. Any infringement claim relying solely on these patents is extinguished. Companies with FTO concerns should verify whether related continuation or divisional applications covering similar subject matter remain active.
The verdict cause is recorded as an Invalidity/Cancellation Action originating at the USPTO, which is consistent with an inter partes review (IPR) or post-grant review (PGR) at the Patent Trial and Appeal Board. The specific proceeding type and petitioner identity are not disclosed in this public record summary but are available in PTAB’s public docket.
The joint appearance of three Western Digital entities alongside inventor Martin Kuster suggests the patents were assigned or exclusively licensed across the corporate family following SanDisk’s acquisition by Western Digital. All entities with standing in the original USPTO proceeding typically join the Federal Circuit appeal to preserve their rights.
Competitors and new entrants in external flash storage can treat US8705243 and US8693206 as cancelled and no longer posing infringement risk. However, Western Digital and SanDisk hold broad flash memory portfolios, and related patents in the same families may cover overlapping technical ground. A full FTO review of the patent families is advisable before drawing any definitive freedom-to-operate conclusion.
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