PTAB challenges

Proceedings overview

One Inter Partes Review (IPR) proceeding has been filed against US patent 10735320. This proceeding, IPR2025-01364, is currently in the "Trial Instituted" phase, meaning the patent claims challenged within it are actively being reviewed for patentability by the Patent Trial and Appeal Board (PTAB). As such, there are no claims that have been invalidated or sustained, nor has the case settled. This active challenge represents an ongoing risk for the patent owner and provides an initial point of defense for a defendant, as the validity of at least some claims is currently under scrutiny.

IPR2025-01364 — Ciena Corporation v. K.Mizra LLC

• Type: Inter Partes Review
• Filed: 2025-08-28
• Status: Trial Instituted. The USPTO Director issued a discretionary decision to refer the petition for merits review on 2026-01-08, and the trial was formally instituted on 2026-02-17.
• Judge panel: The specific panel of Administrative Patent Judges (APJs) assigned to the merits phase of this trial is not publicly available in the provided information or readily discoverable in summary institution notices. Under the current PTAB procedures, the Director typically makes institution decisions and may refer to PTAB judges for consultation or for detailed treatment of complex issues, rather than a full panel making the initial institution decision.
• Petition grounds: The exact claims challenged and specific prior art grounds for this IPR are not explicitly detailed in the public information available. However, Petitioner exhibits filed in the proceeding include references such as a Japanese patent publication JP 2003-258857 ("Taguchi"), "Internet traffic engineering using multi-protocol label switching," and a Korean patent publication KR10-2005-0077938. The grounds would typically be based on anticipation (§ 102) and/or obviousness (§ 103).
• Institution decision: Instituted on 2026-02-17. The Director of the USPTO issued a "Director Discretionary Decision: Refer" on 2026-01-08, indicating that the petition was allowed to proceed to merits review despite discretionary considerations. The full reasoning for institution or the specific claims instituted is not publicly detailed.
• Final Written Decision (if issued): Not yet issued. The statutory deadline for the Final Written Decision is 2027-02-17 (one year from the institution date).
• Settlement / termination: No settlement or termination has been reported; the case is actively in trial.
• Appeal: No appeal has been filed, as no Final Written Decision has been issued.
• Defensive value: This active IPR presents a direct challenge to the patentability of claims in US10735320. A defendant currently facing assertion should closely monitor the progress of this IPR, as a successful challenge could invalidate asserted claims, significantly weakening the patent owner's position.

Strategic summary

US patent 10735320 is currently subject to one active Inter Partes Review, IPR2025-01364, filed by Ciena Corporation. As the IPR has been instituted, claims of the patent are now being reviewed for patentability, but no claims have been canceled or sustained yet. Consequently, all claims of US10735320 are currently untested by a final PTAB decision. The eventual outcome of this IPR will determine which claims, if any, are canceled and which remain patentable.

The estoppel landscape under § 315(e)(2) will only become relevant after a Final Written Decision is issued. If a final written decision finds claims unpatentable, the petitioner (Ciena Corporation) and its privies would be estopped from asserting invalidity grounds that were raised or reasonably could have been raised in the IPR. Until then, prior art grounds remain available. The listed petitioner exhibits suggest a focus on anticipation and/or obviousness grounds based on references like JP 2003-258857 ("Taguchi") and KR10-2005-0077938, among others.

Regarding pattern signals, Ciena Corporation is actively challenging this patent. The IPR was instituted under the new USPTO Director's policy, where the Director personally oversees institution decisions, which often result in summary notices. This means the Director decided that discretionary factors did not warrant denial and referred the case for merits review.

Recommended next steps

For a defendant facing assertion of US patent 10735320:

• Actively monitor IPR2025-01364. The most critical upcoming milestone is the Final Written Decision, which is statutorily due by 2027-02-17 (one year from the institution date).
• Obtain and review the full institution decision document for IPR2025-01364 from the USPTO PTAB E2E (now P-TACTS) system to determine the specific claims challenged and the precise grounds on which the trial was instituted. This will provide clarity on the scope of the challenge.
• Assess the prior art and arguments being used in IPR2025-01364 to determine their potential impact on any claims being asserted against your company.