Untitled case

Zentian Ltd. has initiated a patent infringement lawsuit in the U.S. District Court for the Northern District of California, case number 3:23-cv-02921, asserting U.S. Patent No. 10,839,789. While the specific defendant in this particular district court case is not explicitly stated in all public records with the case number, Zentian Ltd. has been involved in related patent litigation and an Inter Partes Review (IPR) concerning the same patent against [Apple Inc.](/litigations/by-plaintiff/Apple%20Inc.), making Apple a likely defendant or a related party in this or a parallel action. Zentian Ltd. appears to operate as a Patent Assertion Entity (PAE), also commonly referred to as a non-practicing entity (NPE), a company that acquires patents primarily to license or assert them against alleged infringers rather than to produce products themselves.

The asserted patent, U.S. Patent No. 10,839,789, is titled "Speech recognition circuit and method." This patent generally describes a speech recognition system that incorporates an acoustic model memory and a calculating apparatus within a single integrated circuit. Allegations of infringement likely center on devices or services that utilize speech recognition technology, particularly those that integrate these components on-chip. The procedural posture of the case places it in the active litigation phase within the Northern District of California. While a specific judge for 3:23-cv-02921 involving Zentian Ltd. is not immediately clear from the search results, Magistrate Judge Joseph C. Spero is listed for a different 3:24-cv-02921 case, suggesting the court's general docketing practices, but not confirming the judge for this specific patent case. The Northern District of California is a prominent venue for patent litigation, especially in technology-related fields due to the presence of numerous tech companies.

This case is notable due to the patent owner, Zentian Ltd., being a PAE, which frequently leads to litigation focused on licensing and enforcement rather than product competition. Furthermore, the asserted patent, U.S. Patent No. 10,839,789, has been the subject of an Inter Partes Review (IPR) at the Patent Trial and Appeal Board (PTAB), initiated by Apple Inc. The U.S. Court of Appeals for the Federal Circuit recently vacated and remanded a PTAB decision that had favored Zentian Ltd., indicating ongoing challenges to the patent's validity and adding a significant layer of complexity and noteworthiness to any parallel district court infringement proceedings. The Federal Circuit's decision highlighted errors by the PTAB in its interpretation of claim limitations, specifically regarding the size of the acoustic model memory required to fit on the integrated circuit in prior art references. Such IPR linkages are crucial in patent litigation as they can directly impact the strength of infringement claims and potentially lead to stays or dismissal of the district court case based on the outcome of the validity challenges at the PTAB and Federal Circuit.

Key Legal Developments and Outcome for Zentian Ltd. v. Apple Inc. (3:23-cv-02921)

This patent infringement litigation, filed by Zentian Ltd. against Apple Inc. in the U.S. District Court for the Northern District of California (Case No. 3:23-cv-02921), centers on U.S. Patent No. 10,839,789, titled "Speech recognition circuit and method." While the district court case remains active, significant developments have occurred in parallel inter partes review (IPR) proceedings at the Patent Trial and Appeal Board (PTAB) and a subsequent appeal to the U.S. Court of Appeals for the Federal Circuit (CAFC).

Parallel PTAB IPR Proceedings and Federal Circuit Appeal

• IPR Petitions and PTAB Decision: Apple Inc. filed petitions for inter partes review (IPR) of multiple claims of Zentian Ltd.'s U.S. Patent No. 10,839,789. The PTAB ultimately found that Apple had not shown the claims to be unpatentable. While the specific dates for the IPR petitions and PTAB's final written decision are not available in the search results, the subsequent appeal provides a timeline.
• Federal Circuit Appeal (2026-07-21): Apple appealed the PTAB's decision to the Federal Circuit (CAFC Case Nos. 24-2207, 24-2208). On July 21, 2026, the CAFC vacated and remanded the PTAB's decision. The Federal Circuit concluded that the PTAB committed several errors in its interpretation of the patent claims. Specifically, the CAFC found that the PTAB implicitly construed the claimed acoustic model memory "to require holding a large-vocabulary model" and erred by requiring Apple to demonstrate that a large-vocabulary model would fit on an integrated circuit in the prior art. The CAFC clarified that the claim language only requires the acoustic model to "defin[e] a plurality of acoustic states," which includes smaller, abbreviated models, not necessarily large-vocabulary ones. The court noted that the question remains whether on-chip memory disclosed in prior art (Smyth and Mozer) would be sufficient to store an abbreviated acoustic model.

District Court Litigation (3:23-cv-02921)

Specific detailed docket events for the district court case, such as the initial filing date, answers, counterclaims, substantive pre-trial motions, Markman outcomes, discovery milestones, or any trial events, were not readily available in the provided search results. The case is listed as active. Given the recent Federal Circuit remand of the PTAB decision, it is likely that the district court proceedings would have been stayed pending the outcome of the IPR and subsequent appeals, or may see renewed activity following this development, though such a stay is not explicitly confirmed by the current search results.

Zentian Ltd. is represented by the following counsel in patent infringement case 3:23-cv-02921 in the Northern District of California:

• Kayvan B. Noroozi
  • Role: Likely Lead Counsel
  • Firm: Noroozi PC, based in California (admission to practice before the Northern District of California confirmed).
  • Note: Kayvan Noroozi is highly experienced in complex commercial and patent litigation, having litigated before district courts, the Federal Circuit, the Patent Trial and Appeal Board (PTAB), and the International Trade Commission (ITC). He has been recognized as one of the "World's Leading IP Strategists" and profiled by Bloomberg Law as a "next generation" lawyer "changing the game" in intellectual property litigation. Noroozi PC has successfully represented Zentian Ltd. in related PTAB inter partes review (IPR) proceedings against Apple Inc. and Amazon.com concerning speech recognition patents. His experience includes securing significant licensing agreements from major technology companies.

While direct PACER docket entries for this specific case are not publicly available via general web search to confirm all counsel of record, Kayvan B. Noroozi and Noroozi PC are consistently identified as representing Zentian Ltd. in related patent disputes involving the patent at issue (10839789) and defendants like Apple Inc.. Therefore, Kayvan B. Noroozi is a prominent attorney representing Zentian Ltd. in this matter. No other specific attorneys representing Zentian Ltd. in this district court case could be definitively identified from the available public web search results.

While the initial case overview identified Zentian Ltd. as the plaintiff and U.S. Patent No. 10,839,789 as the patent-in-suit, the specific defendant in the district court case 3:23-cv-02921 was not explicitly confirmed. However, further research strongly indicates that Apple Inc. is the defendant in this action. This is supported by multiple sources referencing "Zentian Ltd. v. Apple Inc." in relation to appeals concerning IPRs of Patent No. 10,839,789, including Federal Circuit decisions vacating and remanding PTAB findings for Zentian against Apple.

Identifying the precise counsel of record for Apple Inc. in case 3:23-cv-02921 in the Northern District of California requires reviewing the district court docket directly, which is not fully accessible through public web searches without a PACER account. However, information from related Federal Circuit appeals and IPR proceedings provides strong indications of Apple's legal representation in matters concerning Patent No. 10,839,789.

Based on the available information:

Defendant: Apple Inc.

Counsel of Record for Apple Inc.:

• Jennifer C. Bailey
  • Role: Likely lead counsel or a significant member of the defense team.
  • Firm: Not explicitly stated in the provided snippets for this specific case, but she represented Apple Inc. as an appellee in a related Federal Circuit case, Zentian Ltd. v. Apple Inc. (Case No. 24-2205).
  • Note: Her involvement in the Federal Circuit appeal suggests extensive experience in patent litigation, particularly concerning challenges to patent validity and infringement defense for major technology companies.

It's important to note that without direct access to the docket for 3:23-cv-02921, this information is inferred from related proceedings where Apple Inc. was a party concerning the same patent. Additional attorneys from various firms often staff such complex patent cases, including local counsel for the Northern District of California and in-house counsel for Apple. Filings in the district court would provide the definitive list of all counsel of record.

A "Mandatory Notice to Update Counsel of Record" was filed by the "Petitioner" (Apple Inc.) in IPR proceedings related to Zentian Ltd., further indicating active legal representation. Kayvan B. Noroozi is also mentioned as representing Zentian Ltd. as the Appellant in a Federal Circuit case (24-2205), and has substantial patent litigation experience, but he represents Zentian Ltd., the plaintiff in this district court action, not the defendant, Apple Inc.