Case Summary: Google LLC v. Sonos, Inc., No.24-1097 (Fed. Cir. Aug 28, 2025)

Written by Maxwell Breton

Edited by Madeline Leonard & Maclain Conlin

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(All views expressed in this article are those of the author and do not necessarily represent the position of the Clemson Law Review.)

In a significant decision for patent enforcement, the U.S. Court of Appeals for the Federal Circuit partially reversed a District Court ruling, limiting the application of patent prosecution laches. Laches, as a legal doctrine, incentivizes timely legal action by preventing a party from pursuing a claim after an unreasonable delay if that delay prejudices the opposing party. In patent law, prosecution laches limits the ability of a patent applicant to inexcusably delay prosecution, rendering such patents unenforceable. Applicants, through continuation applications, often seek to keep their claims pending as long as possible, enabling them to strategically adjust their scope. However, if such delays constitute an egregious misuse of the statutory patent system, the patent in question may be held unenforceable.[1]

In 2023, the Northern District of California held that two of Sonos’ patents were unenforceable under prosecution laches in a suit for declaratory judgment of non-infringement filed by Google. Google argued that the intentional delay in prosecution by Sonos caused harm to the company by preventing Google from designing new products around enforceable claims, therefore causing economic damages. After a jury originally awarded Sonos over $30 million for infringement, the District Court later held in a post-trial decision that Sonos had unreasonably delayed prosecution for thirteen years, siding with Google and declaring Sonos’ patents unenforceable.[2] The holding drew widespread criticism from the intellectual property community for contradicting the common patent practice of continuation applications. Following the District Court’s ruling, Gene Quinn, a leading intellectual property commentator and founder of IPWatchdog, remarked that the “filing of a continuation cannot legitimately—either legally, practically or rationally—lead to a finding of laches.”[3] Quinn also clarified that the Supreme Court “specifically said there can be no laches when action is taken within a statutorily defined timeframe.”[4]

On appeal, Sonos argued that the District Court improperly applied the doctrine of prosecution laches. To establish prosecution laches, the burden was placed on Google to prove both of the following elements were present: an unreasonable or inexcusable delay of prosecution, and that the delay resulted in prejudice.[5] As the company argued in District Court proceedings, Google claimed that it suffered economic prejudice due to the prosecution delay. However, Google was unable to substantiate its claim that its new product development predated Sonos’ patent filing by more than four years, or that product development would have progressed differently without the delay.[6] As such, the Federal Circuit reversed the District Court’s ruling that Sonos’ patents were unenforceable due to prosecution laches.

The Federal Circuit’s ruling will likely have a substantial impact on future patent litigation benefiting plaintiffs in infringement suits. Defendants now bear a far greater burden to prove prejudice resulting from prosecution delays and must therefore demonstrate concrete evidence of economic harm. The Federal Circuit also reinforces the high bar of what constitutes an unreasonable and inexcusable delay: filing a continuation within the statutory timeframe weakens a claim of prosecution laches. The decision by the Federal Circuit strengthens the ability for patent holders to pursue infringement damages while encouraging the long-time practice of continuation filing. Ultimately, the ruling in Google v. Sonos narrows the scope of prosecution laches, restoring confidence in common patent prosecution practices and limiting a potential infringement defense.

[1] Google LLC v. Sonos, Inc., No. 24–1097, slip op. at 15 (Fed. Cir. Aug. 28, 2025) (“That doctrine ‘may render a patent unenforceable when it has issued only after an unreasonable and unexplained delay in prosecution that constitutes an egregious misuse of the statutory patent system under the totality of the circumstances.’”).

[2] Id. at 8 (“The court therefore determined that ‘the magnitude of Sonos’s delay in presenting its claims for prosecution sufficed to invoke prosecution laches.’”).

[3] Gene Quinn, Sonos v. Google: A Decision Based on Ignorance of Patent Law That Must Be Overturned, IPWatchdog, Nov. 2, 2023, https://ipwatchdog.com/2023/11/02/sonos-v-google-decision-based-ignorance-patent-law-must-overturned/id=169114/.

[4] Eileen McDermott, CAFC Dodges Key Issues in Reversing District Court Finding for Google on Prosecution Laches, IPWatchdog, Aug. 29, 2025, https://ipwatchdog.com/2025/08/29/cafc-dodges-key-issues-reversing-district-court-finding-google-prosecution-laches/id=191723/.

[5] Sonos, Inc. at 15 (“To succeed in its defense, Google must establish that Sonos’s delay in prosecution was unreasonable and inexcusable under the totality of circumstances, and that Google suffered prejudice attributable to that delay.”).

[6] Id. at 16 (“Google presented no evidence—testimony or otherwise—to support its assertion that its investment in those products actually began in 2015, or that it was caught unawares that Sonos may have already invented the adjudicated-infringing functionality when making those investments”).