Kioxia v. Viasat: Federal Circuit Affirms Flash Memory FEC Patent Unpatentable
Kioxia Corporation and KIOXIA America challenged a lower-tribunal ruling that invalidated US8615700B2 — a patent covering forward error correction with parallel error detection for flash memories. The Federal Circuit affirmed the unpatentability finding on December 19, 2025, ending a 695-day appellate contest.
Federal Circuit Closes the Door on Kioxia’s Flash Memory Error-Correction Patent
Kioxia Corporation and its U.S. subsidiary KIOXIA America, Inc. appealed to the Court of Appeals for the Federal Circuit (Case No. 24-1384) seeking to overturn a ruling that US8615700B2 — covering forward error correction with parallel error detection for NAND flash memories — was unpatentable. The appeal was filed on January 24, 2024, with Viasat, Inc. defending the invalidity finding below. Baker Botts LLP represented Kioxia; Bartlit Beck LLP and Zimmer, Citron & Clarke LLP defended Viasat.
On December 19, 2025, the Federal Circuit issued a terse but definitive order: AFFIRMED. The court found no reversible error in the underlying unpatentability determination, leaving the cancellation of US8615700B2’s claims intact. For Kioxia, this means the patent — and any enforcement leverage it carried — is extinguished at the appellate level, with no remaining recourse short of a petition to the Supreme Court.
The 695-day duration suggests meaningful briefing and possibly oral argument, though the public record does not disclose the specific grounds of unpatentability upheld. What drove the outcome — whether anticipation, obviousness, or written-description failure — remains undisclosed in the available record. The affirmance is significant for the flash memory sector: error-correction IP portfolios will need to be reassessed in light of this ruling, and competitors previously concerned about US8615700B2 gain meaningful freedom-to-operate clarity.
Filing to Unpatentable in 695 days
695-day appellate proceeding — above median for Federal Circuit patent appeals
Federal Circuit affirms: what the unpatentability ruling means for both parties
Affirmance means the lower unpatentability finding is final
When the Federal Circuit affirms, it has reviewed the record and found no reversible error in the tribunal below. The standard of review for factual findings in patent validity proceedings is substantial evidence; legal conclusions are reviewed de novo. Here, affirmance signals that Kioxia failed to demonstrate reversible error on either front — the claims of US8615700B2 remain cancelled as unpatentable.
No reversible error foundKioxia loses US8615700B2 — enforcement options exhausted at Federal Circuit
With affirmance, Kioxia’s US8615700B2 patent on forward error correction for flash memories is unpatentable and unenforceable. Kioxia may petition the Supreme Court for certiorari, but grant rates are extremely low in patent validity cases. The commercial and licensing value of this specific patent is effectively eliminated, requiring Kioxia to rely on other IP assets for protection in the FEC flash memory space.
Patent cancelled — appeal exhaustedViasat secures a cleared patent — threat from US8615700B2 removed
Viasat, having defended the invalidity finding through appellate review, now operates free from the threat of infringement claims under US8615700B2. The affirmance strengthens Viasat’s position across any product lines that may have intersected with the patent’s claims covering parallel error detection in flash memory contexts. The result also raises the bar for any future attempt to enforce similar claims against Viasat.
Infringement risk from this patent eliminatedFlash memory FEC patent landscape narrows — sector gains FTO clarity
The affirmance removes US8615700B2 from the landscape of enforceable flash memory IP. Companies developing or deploying forward error correction with parallel error detection in NAND flash architectures — including storage controllers, SSD firmware, and memory interface IP — may now operate with greater freedom regarding this specific patent. Competitors should nonetheless audit related Kioxia patents in the same family or filing cohort.
FTO landscape clarified for FEC flash IPFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Kioxia Corporation | Company | Flash memory manufacturer — holder of US8615700B2 covering FEC for NAND flashSearch in Eureka ↗ |
| Co-Plaintiff | KIOXIA America, Inc. | Company | Search in Eureka ↗ |
| Defendant | Viasat, Inc. | Company | Viasat, Inc. — satellite communications and technology company defending invalidity findingSearch in Eureka ↗ |
| Plaintiff counsel | Michael Hawes. | Attorney | Counsel for Kioxia CorporationSearch in Eureka ↗ |
| Plaintiff law firm | Baker Botts LLP | Law Firm | Representing Kioxia CorporationSearch in Eureka ↗ |
| Defendant counsel | David Zimmer | Attorney | Counsel for Viasat, Inc.Search in Eureka ↗ |
| Defendant counsel | John Scott McBride | Attorney | Counsel for Viasat, Inc.Search in Eureka ↗ |
| Defendant counsel | Matthew R. Ford | Attorney | Counsel for Viasat, Inc.Search in Eureka ↗ |
| Defendant counsel | Meg E. Fasulo | Attorney | Counsel for Viasat, Inc.Search in Eureka ↗ |
| Defendant counsel | Nevin M. Gewertz | Attorney | Counsel for Viasat, Inc.Search in Eureka ↗ |
| Defendant counsel | Nosson Knobloch | Attorney | Counsel for Viasat, Inc.Search in Eureka ↗ |
| Defendant counsel | Ravi Shah | Attorney | Counsel for Viasat, Inc.Search in Eureka ↗ |
| Defendant law firm | Bartlit Beck LLP | Law Firm | Representing Viasat, Inc.Search in Eureka ↗ |
| Defendant law firm | Zimmer, Citron & Clarke LLP | Law Firm | Representing Viasat, Inc.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 — ‘AFFIRMED’ on the basis of unpatentability — is unambiguous in scope: the lower tribunal’s determination that US8615700B2 is unpatentable survives appellate review intact. At the Federal Circuit, affirmance requires that the panel found no reversible legal error and that any factual findings were supported by substantial evidence. The terse order form suggests a lack of significant dissent or novel legal question, consistent with a straightforward application of established patentability doctrine to the record below. For Kioxia, no claim survives; for Viasat, the cleared status is judicially confirmed.
US8615700B2 — Forward Error Correction for Flash Memories
US8615700B2 (application number US12/858510) covers forward error correction (FEC) with parallel error detection for flash memory systems — a core data integrity mechanism in NAND flash storage. FEC is essential for compensating for the inherent bit-error rates of flash cells, particularly as cell geometries shrink. Parallel error detection architectures improve throughput and latency in high-density storage applications. The patent’s claims, now cancelled, addressed innovations at the intersection of error coding and flash memory controller design.
This patent sat at a commercially sensitive juncture in the flash memory supply chain: FEC logic is embedded in SSD controllers, enterprise storage arrays, and embedded flash systems. For a company of Kioxia’s scale — one of the world’s largest NAND flash producers — such patents represent both defensive moats and potential licensing leverage against controller and firmware vendors. The Federal Circuit’s affirmance of unpatentability eliminates this specific IP asset from Kioxia’s enforcement arsenal and signals that the prior art landscape in flash FEC is dense enough to challenge even foundational claims.
Should you run an FTO analysis against US8615700B2?
While US8615700B2 has been declared unpatentable and affirmed as such by the Federal Circuit, product and R&D teams working on forward error correction architectures for flash memory should not treat this as a complete clearance event. Related patents in the same Kioxia family — continuations, divisionals, or foreign counterparts — may contain overlapping claim scope and remain enforceable. Any team shipping SSD controllers, flash memory interfaces, or embedded storage firmware with FEC functionality should conduct a comprehensive FTO covering the broader Kioxia NAND patent estate.
PatSnap Eureka’s FTO Search Agent can map US12/858510’s patent family, identify surviving siblings, and surface prior art clusters that informed this unpatentability finding — giving your IP and engineering teams a structured, cite-ready landscape in hours. Use Eureka to run a cross-jurisdictional FTO against Kioxia’s flash memory portfolio and flag any live claims that intersect with your parallel error detection implementation.
Run a freedom-to-operate analysis on US8615700B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit Flash Memory Patent Appeals
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What this case signals for the flash memory and storage IP landscape
The Federal Circuit’s affirmance in Kioxia v. Viasat reshapes enforceability assumptions around flash memory error-correction patents.
Error-correction IP in flash memory faces elevated invalidity risk at the Federal Circuit
This affirmance is consistent with a broader pattern of Federal Circuit scrutiny applied to flash memory method patents. Companies holding or acquiring FEC-related patents — particularly those covering parallel error detection architectures — should audit claim strength proactively before any enforcement strategy is considered.
Viasat’s successful defence clarifies FTO for parallel error detection implementations
With US8615700B2 cancelled and affirmed unpatentable, any product or system using forward error correction with parallel error detection in flash memory no longer faces this specific patent risk. Practitioners advising clients on NAND flash storage products should update FTO opinions to reflect this outcome and note the now-cleared claim space.
Kioxia v Viasat — key questions answered
The Federal Circuit affirmed the unpatentability of US8615700B2 on December 19, 2025. The court found no reversible error in the lower tribunal’s invalidity determination, leaving the patent’s claims cancelled. Kioxia’s appeal was unsuccessful after 695 days of appellate proceedings.
US8615700B2 (application US12/858510) covers forward error correction with parallel error detection for flash memories. FEC is a critical data integrity technology in NAND flash storage systems, embedded in SSD controllers and enterprise storage arrays. As a Kioxia-held patent, it represented a potential licensing and enforcement asset in the high-volume flash memory supply chain.
The affirmance cancels US8615700B2, providing freedom-to-operate clarity specifically for that patent. However, practitioners should not assume complete clearance — related Kioxia patents in the same family may survive. Companies developing FEC implementations for NAND flash should conduct a full FTO covering the broader Kioxia portfolio and any foreign counterparts.
The public record available for Case No. 24-1384 does not disclose the specific grounds — whether anticipation, obviousness, or another basis — on which unpatentability was affirmed. The Federal Circuit’s order states only ‘AFFIRMED’ with a basis of termination listed as ‘Unpatentable.’ Full reasoning would typically appear in a written opinion, if published.
Kioxia was represented by Baker Botts LLP (attorney Michael Hawes). Viasat fielded a larger team across two firms: Bartlit Beck LLP and Zimmer, Citron & Clarke LLP, with attorneys including David Zimmer, John Scott McBride, Matthew R. Ford, Meg E. Fasulo, Nevin M. Gewertz, Nosson Knobloch, and Ravi Shah.
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