PTAB challenges

Proceedings overview

One AIA trial proceeding has been filed against US Patent 7420952, resulting in one institution denial. This outcome means all claims of the patent remain intact from a PTAB perspective, giving the patent owner a strong defensive posture against any party that was in privity with the petitioner.

IPR2025-01523 — Cisco Systems, Inc. v. Dynamic Mesh Networks Inc.

• Type: Inter Partes Review
• Filed: 2025-09-08
• Status: Discretionary Denial. This means the PTAB declined to institute a trial, and no claims were adjudicated on the merits.
• Judge panel: Administrative Patent Judges Jennifer B. Lim, Rama G. Elluru, and John F. Zizzo.
• Petition grounds: The petition challenged claims 1-20 of U.S. Patent No. 7,420,952. The grounds were based on obviousness under 35 U.S.C. § 103, primarily using combinations of U.S. Patent Publication No. 2004/0090943 A1 (da Costa) and U.S. Patent Publication No. 2004/0109430 A1 (da Costa).
• Institution decision: Denied on 2026-02-19. The Board exercised its discretion to deny institution under 35 U.S.C. § 314(a) based on the patent's expiration. The Board found that the patent expired on May 21, 2025, which was before the petition was filed on September 8, 2025. The Board determined that, even if instituted, it could not issue a final written decision because there would be no claims to cancel, as the patent itself had expired.
• Final Written Decision: Not applicable, as institution was denied.
• Settlement / termination: Not applicable, as institution was denied due to the patent's expiration.
• Appeal: No appeal to the Federal Circuit regarding the institution denial was found in publicly available dockets.
• Defensive value: This proceeding confirms that all claims of US7420952 remain patentable as far as the PTAB is concerned, as the Board explicitly denied institution on procedural grounds related to the patent's expiration rather than on the merits of the prior art. Any party facing assertion of this patent will need to evaluate the claims against prior art in district court, as the IPR process was unavailable here.

Strategic summary

All claims (1-20) of US7420952 remain UNTESTED by the PTAB. The single IPR filed against the patent, IPR2025-01523, was discretionarily denied institution not because the claims were found patentable, but because the patent had already expired prior to the petition being filed. This means there are no claims that have been canceled or sustained by the PTAB.

The estoppel landscape from IPR2025-01523 is relatively limited. While Cisco Systems, Inc. (and its privies) would be estopped from raising the specific prior art grounds they raised or reasonably could have raised in a subsequent PTAB proceeding, the patent's expiration makes further IPRs against this patent impossible anyway. The prior art cited in the petition (da Costa 2004/0090943 and da Costa 2004/0109430) could still be asserted in district court by any defendant, including Cisco, in a defense against infringement.

There are no apparent pattern signals beyond this single IPR. The fact that the IPR was filed after the patent's expiration and was subsequently denied on those grounds suggests a potential oversight by the petitioner or an attempt to achieve a specific legal outcome given the expiration.

Recommended next steps

The patent has expired as of 2025-05-21. Therefore, if you are a defendant facing assertion, you cannot be sued for new infringement going forward. Any current or past assertions would be for acts of infringement that occurred before the patent's expiration. The PTAB proceeding IPR2025-01523 was denied institution precisely because the patent had expired, rendering the IPR trial moot. For details, refer to the institution decision for IPR2025-01523, available on the USPTO PTAB E2E portal. The relevant reasoning from the Board states: "Because the ’952 patent expired prior to Petitioner filing the Petition, we exercise our discretion under 35 U.S.C. § 314(a) to deny institution. Even if we were to institute, we could not issue a final written decision because there would be no claims to cancel."