PTAB challenges

Proceedings overview

There are two AIA trial proceedings on US patent 12373366, both with a status of "Discretionary Denial." Both were Post-Grant Review (PGR) and Inter Partes Review (IPR) petitions filed by [[[Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.), Ltd.](/litigations/by-plaintiff/Samsung%20Electronics%20Co.%2C%20Ltd.) et al.](/litigations/by-plaintiff/Samsung%20Electronics%20Co.%2C%20Ltd.%20et%20al.) The patent has survived these initial challenges, suggesting a hardened defensive posture for the patent owner, Netlist Inc., against these specific petitioners and grounds.

PGR2026-00001 — Samsung Electronics Co., Ltd. et al. v. Netlist Inc.

• Type: Post-Grant Review
• Filed: 2025-11-07
• Status: Discretionary Denial - The petition was denied institution by the PTAB.
• Judge panel: Not publicly available yet for discretionary denial decisions.
• Petition grounds: Not publicly available yet for discretionary denial decisions.
• Institution decision: Denied on 2026-04-28. The panel's reasoning for discretionary denial is not yet publicly detailed but typically involves factors such as parallel litigation, inefficient use of Board resources, or the strength of the petitioner's asserted grounds.
• Final Written Decision: Not applicable; institution was denied.
• Settlement / termination: Not applicable.
• Appeal: Not applicable.
• Defensive value: The patent owner successfully prevented institution of this PGR, meaning the claims challenged in this petition remain intact. This strengthens the patent owner's position against Samsung and parties in privity with Samsung, at least for the grounds that were or could have been raised.

IPR2026-00018 — Samsung Electronics Co., Ltd. et al. v. Netlist Inc.

• Type: Inter Partes Review
• Filed: 2025-11-07
• Status: Discretionary Denial - The petition was denied institution by the PTAB.
• Judge panel: Not publicly available yet for discretionary denial decisions.
• Petition grounds: Not publicly available yet for discretionary denial decisions.
• Institution decision: Denied on 2026-04-28. Similar to the PGR, the panel exercised discretionary denial, the specific reasoning for which is not yet publicly detailed but would have considered factors such as judicial economy or the merits of the petition itself.
• Final Written Decision: Not applicable; institution was denied.
• Settlement / termination: Not applicable.
• Appeal: Not applicable.
• Defensive value: The patent owner successfully avoided institution of this IPR. For a defendant currently facing assertion from this patent, this indicates that the claims challenged in this IPR by Samsung remain patentable. This outcome provides a level of hardening for the patent against IPR challenges by Samsung and its privies on the same or substantially similar grounds.

Strategic summary

Both AIA trial proceedings, PGR2026-00001 and IPR2026-00018, were filed by Samsung Electronics Co., Ltd. et al. against US patent 12373366 and both resulted in discretionary denials of institution on 2026-04-28. This means that none of the claims of US patent 12373366 were invalidated or sustained by the PTAB in these proceedings, as no trial was instituted. Therefore, all claims of US patent 12373366 remain untested by a full PTAB trial.

Regarding the estoppel landscape, since institution was denied in both cases, the statutory estoppel provisions of § 315(e)(2) for IPRs (and similar for PGRs) would not typically apply in the same way they would if a final written decision had been issued. However, petitioners (and their privies) may be precluded from raising the same grounds again in subsequent petitions or district court litigation, particularly if the discretionary denial was based on the merits of the petition or strategic considerations like the Fintiv factors. The specific reasoning for the discretionary denials would be crucial to fully assess the extent of any potential estoppel. As the specific petition grounds are not publicly detailed for these denials, it's difficult to definitively state which prior-art grounds are still available.

The pattern signals indicate that Samsung Electronics Co., Ltd. et al. attempted to challenge this patent through both PGR and IPR, suggesting they perceived weaknesses in the patent. The discretionary denials, however, represent a win for the patent owner, Netlist Inc., preventing a full review of the claims by the PTAB. The involvement of a significant market player like Samsung suggests the patent has commercial relevance and is being asserted.

Recommended next steps

For a defendant currently facing assertion of US patent 12373366, it's important to understand the specific reasons for the discretionary denials in PGR2026-00001 and IPR2026-00018. While the full decisions are not yet available, checking the USPTO PTAB E2E system for the detailed institution denial orders once they are published would be critical. These orders would shed light on whether the denial was based on procedural grounds, insufficient showing of unpatentability, or discretionary factors such as Fintiv.

Given that both petitions were denied institution, all claims of US patent 12373366 are currently presumed valid as far as these PTAB proceedings are concerned. A defendant would need to develop their own non-infringement or invalidity arguments, potentially exploring different prior art or legal theories not raised (or considered by the Board) in the Samsung petitions. The absence of an active PTAB trial means there are no trial-stage milestones to track for these specific proceedings.