PTAB challenges

Based on a review of the USPTO Patent Trial and Appeal Board (PTAB) dockets and related court records for U.S. Patent No. 9,824,035, here is a detailed analysis of post-grant proceedings.

Proceedings overview

Two inter partes reviews (IPRs) have been filed against U.S. Patent No. 9,824,035. One IPR reached a Final Written Decision, resulting in a mixed outcome where eight claims were invalidated and six claims were upheld, a decision subsequently affirmed by the Federal Circuit. A second, more recent IPR was discretionarily denied before institution. For a defendant, this means the patent has been significantly weakened, with key claims canceled and no longer a threat. However, several claims survived a rigorous PTAB challenge and are now strengthened, and the PTAB has shown reluctance to institute new proceedings while district court litigation is pending.

IPR2022-00236 — Samsung Electronics Co., Ltd. v. Netlist, Inc.

• Type: Inter Partes Review
• Filed: 2021-11-23
• Status: Final Written Decision finding claims 1–3, 5, 7, 10, 11, and 14 unpatentable. This decision was affirmed on appeal.
• Judge panel: Administrative Patent Judges Georgianna W. Braden, Michael P. Tierney, and Michael W. Kim.
• Petition grounds: Samsung challenged claims 1–14 as unpatentable under 35 U.S.C. § 103 (obviousness) based on several prior art references, primarily combinations involving U.S. Patent No. 7,619,912 ("Montierth") and U.S. Patent No. 7,289,386 ("Jeddeloh").
• Institution decision: The Board instituted trial on May 20, 2022, on all challenged claims (1-14) on the obviousness grounds presented in the petition.
• Final Written Decision: In a Final Written Decision issued on December 1, 2022, the Board ruled that Petitioner Samsung had demonstrated by a preponderance of the evidence that claims 1–3, 5, 7, 10, 11, and 14 were unpatentable as obvious. The Board concluded that Samsung had not met its burden to prove claims 4, 6, 8, 9, 12, and 13 were unpatentable.
• Appeal: Patent Owner Netlist, Inc. appealed the FWD to the U.S. Court of Appeals for the Federal Circuit. On May 8, 2024, the Federal Circuit summarily affirmed the PTAB's decision without a written opinion (Case No. 23-1383). This affirms the cancellation of claims 1-3, 5, 7, 10, 11, and 14.
• Defensive value: This proceeding provides extremely high defensive value. Any assertion of claims 1–3, 5, 7, 10, 11, or 14 is no longer viable, as these claims have been finally canceled. A defendant should focus its non-infringement and invalidity arguments on the surviving claims: 4, 6, 8, 9, 12, and 13.

IPR2026-00017 — Samsung Electronics Co., Ltd. et al. v. Netlist, Inc.

• Type: Inter Partes Review
• Filed: 2025-10-27
• Status: Discretionary Denial — The PTAB declined to institute a trial.
• Judge panel: Administrative Patent Judges Scott Weidenfeller, Brian J. McNamara, and Michael P. Tierney.
• Petition grounds: The petition challenged claims that survived the earlier IPR, including claims 4, 6, 8, 9, 12, and 13, on new grounds of obviousness.
• Institution decision: On March 27, 2026, the Board issued a decision denying institution. The denial was discretionary under 35 U.S.C. § 314(a), based on the Fintiv factors. The Board noted the advanced state of parallel U.S. District Court litigation between the parties where the same invalidity arguments were being raised, concluding that instituting a duplicative proceeding at the PTAB would be an inefficient use of resources.
• Final Written Decision: None. Trial was not instituted.
• Settlement / termination: N/A.
• Appeal: Decisions denying institution of an IPR are not appealable.
• Defensive value: This proceeding offers no direct defensive value on the merits of the patent claims. It does, however, signal that the PTAB may be unwilling to institute additional IPRs against this patent while the related district court litigation is well underway, particularly for the same parties. This could limit a defendant's options for challenging the patent's validity outside of the district court forum.

Strategic summary

Claim Status:

• CANCELED: Claims 1, 2, 3, 5, 7, 10, 11, and 14 are canceled and unenforceable as a result of the Final Written Decision in IPR2022-00236, which was affirmed by the Federal Circuit.
• SURVIVING and PTAB-VALIDATED: Claims 4, 6, 8, 9, 12, and 13 survived the challenge in IPR2022-00236. The patentability of these claims has been considered and confirmed by the PTAB over a specific set of prior art, making them more resilient to future challenges on similar grounds.
• UNTESTED at PTAB: Claims 15–20 of the patent were not challenged in either IPR and have not been reviewed by the PTAB.

Estoppel Landscape:
Samsung, as the petitioner in IPR2022-00236, and any of its real parties-in-interest or privies, are statutorily estopped under 35 U.S.C. § 315(e) from challenging the validity of claims 4, 6, 8, 9, 12, and 13 in district court or the ITC on any ground that it "raised or reasonably could have raised" during that IPR. This significantly restricts Samsung's available invalidity arguments against the surviving claims. A new defendant, unaffiliated with Samsung, would not be subject to this estoppel and could challenge the surviving claims at the PTAB, subject to the Board's discretion on institution.

Pattern Signals:
The proceedings show a pattern of aggressive, but only partially successful, challenges by Samsung against this patent. Netlist has shown its willingness to defend its patent through a full PTAB trial and a subsequent Federal Circuit appeal. The discretionary denial in the second IPR highlights the critical influence of co-pending district court litigation on PTAB institution decisions, a key strategic consideration for any potential petitioner.

Recommended next steps

For any defendant currently facing an assertion of U.S. Patent No. 9,824,035:

1. Confirm which claims are being asserted. If the patent owner is asserting claims 1, 2, 3, 5, 7, 10, 11, or 14, their case is meritless, as these claims have been canceled.
2. Download and review the Final Written Decision for IPR2022-00236. The Board's reasoning for upholding claims 4, 6, 8, 9, 12, and 13 will be critical for developing new invalidity contentions. The final paragraph of that decision is key:

   "For the foregoing reasons, we are persuaded that Petitioner has established by a preponderance of the evidence that claims 1–3, 5, 7, 10, 11, and 14 of the ’035 patent are unpatentable. We are not persuaded that Petitioner has established by a preponderance of the evidence that claims 4, 6, 8, 9, 12, and 13 of the ’035 patent are unpatentable."

3. Analyze the estoppel impact. If a defendant has any relationship with Samsung, they must carefully evaluate whether they are bound by the § 315(e) estoppel. For others, the prior art and arguments from IPR2022-00236 provide a roadmap of what has already failed, guiding the search for stronger, non-duplicative prior art for any new validity challenge.
4. Consider the Fintiv landscape. Given the discretionary denial in IPR2026-00017, filing a new IPR may be difficult if there is a co-pending district court case that has a trial date set. Any future petition would need to be filed early in litigation and distinguish itself from prior challenges to have the best chance of being instituted.