IP Law Daily, PATENT—Fed. Cir.: Google secures revival of hotword-detection patents in dispute with Sonos, (Jun 11, 2026)

By Saurabh Kashyap, B.A., M.A., LL.B., LL.M.

The Board relied on prior art that did not disclose devices exchanging messages while remaining in a low-power mode.

Google’s patents covering hotword-detection technology were revived by the U.S. Court of Appeals for the Federal Circuit. The court reversed the Patent Trial and Appeal Board’s (PTAB) decisions that had invalidated the challenged claims. The court found that substantial evidence did not support the Board’s determination that the primary prior-art reference disclosed devices exchanging messages while remaining in a low-power mode, a limitation required by the challenged claims. The court also declined to affirm an alternative anticipation theory because the Board had not made factual findings on that issue (Google LLC v. Sonos, Inc., No. 24-2119 (Fed. Cir. Jun. 9, 2026)).

Background. The dispute arose between Google and Sonos, Inc., a manufacturer of wireless audio systems and smart speakers. Sonos challenged the patents through inter partes review proceedings before the PTAB, in which it succeeded in obtaining rulings that the asserted claims were unpatentable.

The patents at issue were U.S. Patent Nos. 10,134,398 (the ’398 patent) and 10,593,330 (the ’330 patent). The patents concern improvements in hotword-detection systems used in voice-enabled devices, such as smart speakers and digital assistants. According to the patents, multiple devices may detect the same wake phrase, potentially leading to simultaneous responses from multiple devices.

Sonos filed petitions for inter partes review challenging claims 1–5, 7–13, and 15–20 of the ’398 patent and claims 1–7, 9–15, and 17–18 of the ’330 patent. Sonos argued that the claims were anticipated by U.S. Patent No. 8,340,795 (Rosenberger) and, for certain dependent claims, would have been obvious over Rosenberger in combination with U.S. Patent Application Publication No. 2014/0163978 (Basye). The Board agreed, finding numerous claims anticipated by Rosenberger and the remaining challenged claims obvious over Rosenberger and Basye. Google appealed.

Board’s anticipation findings. Google contended that the Board erred in finding that Rosenberger disclosed limitations requiring devices to exchange outputs or messages while remaining in a low-power mode. According to Google, Rosenberger required devices to exit their low-power state before exchanging coordination information, meaning the reference could not anticipate the challenged claims.

The Federal Circuit agreed. The Board had relied on a passage in Rosenberger describing devices that normally operate in a low-power “listening” mode and that coordinate to determine which device is best positioned to handle user interaction. The Board credited expert testimony asserting that the devices exchanged weighted signals while still in low-power mode. However, the appellate court concluded that the cited portion of Rosenberger did not disclose any exchange of weighted signals, much less one that occurred while devices remained in the low-power listening state.

The court explained that the “device coordination discussion” referenced by the Board actually described embodiments in which devices first exited the low-power listening mode and then calculated and exchanged weighted signals. Because anticipation requires a single prior-art reference to disclose every claim limitation, the absence of a disclosure showing message exchanges while remaining in low-power mode was fatal to the Board’s anticipation determination. The court relied on In re NTP, Inc., 654 F.3d 1279, 1302 (Fed. Cir. 2011), to highlight that failure to disclose a required claim element requires reversal of an anticipation rejection.

Alternative arguments. Sonos offered two reasons why the Board’s findings should nevertheless be upheld. First, Sonos argued that Rosenberger’s disclosure of a device changing its status light reasonably indicated a transition from a low-power state to a higher-power operating state only after the coordination process had occurred. The Federal Circuit rejected that argument, finding no disclosure in Rosenberger linking a status-light change to a transition out of the low-power listening mode. Instead, the reference merely described changing the status light as one way of prompting a user to provide further commands.

Second, Sonos contended that Rosenberger’s reference to a device “waking up” after determining it was best positioned to interact with the user demonstrated that the device remained in low-power mode during coordination. The court again disagreed. Examining Rosenberger's text, the court found that determining which device was best positioned to respond and instructing a device to wake up were disclosed as separate alternatives rather than sequential steps linked by a causal relationship. The Board’s contrary interpretation, therefore, lacked substantial evidentiary support.

Alternative low-power-mode theory. Further, Sonos requested affirmation on a separate theory not adopted by the Board. According to Sonos, even if Rosenberger’s devices were not operating in the self-described “listening” mode while exchanging coordination messages, they nevertheless remained in another low-power state because they consumed less power than during full operation. Sonos argued that this reduced-power state satisfied the parties agreed construction of “low power mode” as an operating state in which power is conserved.

The Federal Circuit declined to address that theory. The court noted that the Board had made no factual findings concerning whether Rosenberger disclosed such an alternative low-power mode. Citing Regents of the University of California v. Broad Institute, Inc., 903 F.3d 1286, 1294 (Fed. Cir. 2018), the court explained that appellate review is limited to findings actually made by the Board and does not extend to making new factual determinations in the first instance. That issue, the court said, could be considered by the Board on remand.

The Federal Circuit therefore reversed the Board’s determinations that claims 1–3, 7–11, and 15–18 of the ’398 patent and claims 1–3, 5, 7, 9–11, 13, 15, and 17–18 of the ’330 patent were anticipated by Rosenberger or obvious over Rosenberger and Basye and remanded the proceedings for further consideration. Costs were awarded to Google.

The Case is No. 24-2119.

Judge: Moore, K.

Attorneys: Erika Arner (Finnegan, Henderson, Farabow, Garrett & Dunner, LLP) for Google LLC. Robert Manhas (Orrick, Herrington & Sutcliffe LLP) for Sonos, Inc.

Companies: Google LLC; Sonos, Inc.

Cases: Patent FedCirNews TechnologyInternet