Prosecution laches is an equitable defense in patent litigation that dates back to the early 1900s. See Woodbridge v. United States, 263 U.S. 50 (1923); Webster Elec. Co. v. Splitdorf Elec. Co., 264 U.S. 463 (1924). An alleged infringer may invoke this defense to render a patent unenforceable if the patentee's delay in prosecution is unreasonable and inexcusable, and there is some corresponding prejudice attributable to the delay. Unlike traditional laches that is aimed at protecting a particular competitor, a primary purpose of prosecution laches is to serve the public's interest. For example, the Supreme Court has expressed that "[a]ny practice by the inventor and applicant for a patent through which he deliberately and without excuse postpones beyond the date of the actual invention, the beginning of the term of his monopoly, and thus puts off the free public enjoyment of the useful invention, is an evasion of the statute and defeats its benevolent aim." Woodbridge, 263 U.S. at 50.
Over the past century, the doctrine of prosecution laches has been raised and applied primarily in the context of "submarine" patents. The term "submarine patent" refers to a former practice by patentees in which continuations in a patent family were filed and abandoned successively, thereby keeping the family alive as long as possible, and allowing the patentee to craft claims covering interim developments in the industry. Because, prior to changes in U.S. patent law in the 1990s, the term of a U.S. patent was 17 years from issuance, patentees who employed a submarine patent strategy could issue patent claims after industry adoption of a technology and prolong the life of those patent claims. The existence of these patents remained hidden until an opportune moment for the patentee, at which point they would issue and "surface" to catch companies and the public off guard.
On June 8, 1995, however, the term of a patent was changed from 17 years from issuance to 20 years from filing due to adoption of the Uruguay Round of the General Agreement on Tariff and trade ("GATT"). As a result of this change, patent applications flooded the PTO in early 1995 just prior to institution of the new rules—a period later known as the "GATT Bubble." After the new rules took hold, patentees were generally dissuaded from "submarining" a patent because delays in prosecution had no practical effect on the overall term of the patent, which now runs from filing and not issuance. Nevertheless, numerous submarine patents were filed as part of the GATT Bubble and later litigated, leading to the resurgence of the prosecution laches defense. See, e.g., In re Bogese, 303 F.3d 1362, 1369 (Fed. Cir. 2002) (finding patents unenforceable based on an eight-year delay); Symbols Techs., Inc. v. Lemelson Med., 277 F.3d 1363, 1366-68 (Fed. Cir. 2002) (finding asserted patents unenforceable due to 18-39 year delays); Cancer Rsch. Tech. Ltd. v. Barr Labs., Inc., 625 F.3d 724, 728-29 (Fed. Cir. 2010) (requiring patentee's delay in prosecution be unreasonable and inexcusable under the totality of circumstances, and prejudice attributable to the delay).
Even now, several decades after the GATT amendments, the Federal Circuit remains faced with cases in which prosecution laches of GATT Bubble submarine patents is at issue. See https://www.quinnemanuel.com/the-firm/publications/lead-article-snooze-think-again-prosecution-laches-and-why-applicants-and-litigants-should-beware/ (Feb. 8, 2022). For example, in Hyatt v. Hirshfeld, prosecution laches was raised in the context of four patent applications filed during the GATT Bubble. 998 F.3d 1347 (Fed. Cir. 2021). At issue in the case was the PTO's rejection of claims across four of the applications filed by the patentee, Hyatt. Hyatt filed suit under 35 U.S.C. § 145 seeking issuance of the rejected claims, and the PTO moved to dismiss the action based on prosecution laches. The PTO's argument was that Hyatt had engaged in a pattern of delay in prosecuting his applications, including in adding claims between 12 and 28 years after their claimed priority dates. The district court concluded that prosecution laches did not bar the issuance of the patent applications at issue. However, on appeal, the Federal Circuit vacated and remanded that determination, finding that the district court erred by failing to consider the "totality of circumstances," including facts showing that Hyatt's delay in prosecuting the claims and applications was unreasonable and inexcusable, and that he had obstructed the PTO from examining the applications at issue. Id.
The doctrine was again addressed by the Federal Circuit in Personalized Media Commc'ns v. Apple Inc. ("PMC"), another case in which the patentee had filed hundreds of GATT Bubble applications. 57 F.4th 1346 (Fed. Cir. 2023). In PMC, the Federal Circuit affirmed the district court's finding of unenforceability due to prosecution laches, which was based on the totality of the circumstances, including that the patentee had waited 8 to 14 years to file its subject applications and at least 16 years to present its subject claims for examination. In particular, though extension of the patent monopoly was a concern, both the district court and the Federal Circuit specifically referenced the patentee's inexcusable delay in introducing the accused subject matter into the patent claims (i.e., "the subject encryption and decryption limitations") as one of the bases for finding prosecution laches.
Despite traditionally being raised in the context of submarine patents, prosecution laches is a broad equitable doctrine and, thus, practitioners should be aware that its elements and policy goals can apply in broader contexts. For example, Quinn Emanuel recently successfully raised prosecution laches as a defense against two post-GATT patents in which the patentee's delays in prosecution were not directed to extending the life of the subject patents. Rather, in Sonos, Inc. v. Google LLC, the patentee, Sonos, waited more than a decade to file the two patents at issue and raise new subject matter in its claims. Sonos did this not to extend the life of the patents, but to spring its patents on Google after Google and the industry had already released the accused technologies. No. C 20-06754 WHA, 2023 WL 6542320, at *2 (N.D. Cal. Oct. 6, 2023). Judge William H. Alsup of the Northern District of California found that prosecution laches applied to bar Sonos's claims based on the totality of the circumstances, including that Sonos had waited over a decade to introduce the specific subject matter at issue into its claims and, importantly, that the newly-added subject matter was not supported by or disclosed in Sonos's priority applications. The court found that "in 2019, during the prosecution of the applications for the patents in suit, Sonos amended the specification to insert new matter, despite telling the patent examiner the inserted matter was not new." Id. at *1. Additionally, Sonos accelerated prosecution of the two applications using the PTO's "Track One" prioritized examination procedures, while simultaneously disclosing over 70,000 pages of prior art and other documents to the PTO examiner. Id. at *12-13.
Notably, as part of its analysis, the district court expressly found that prosecution laches is still a viable defense for post-GATT patents. The district court noted, for example, that if the doctrine were dead with respect to post-GATT patent applications, "it would have been easy for the Federal Circuit to say so in opinions issued after 1995." Id. at *19. The district court further reasoned that the Supreme Court was less concerned with the nuances of patent term duration in the context of equitable defenses, and more concerned with manipulation of the patent monopoly for profit at the expense of the public. Id.
Although there was no extension of the expiration date of the two post-GATT patents at issue in Sonos, the district court nevertheless found the application of prosecution laches was warranted in view of the patentee's "designed delay" in prosecution that "imposed limitations on the public's right to practice the invention after the fact, at considerable expense to Google, other companies, and consumers." Id. at *20.
Takeaways
The recent Federal Circuit PMC and Northern District of California Sonos decisions indicate that prosecution laches is still a viable tool in an accused infringer's arsenal of defenses, even when faced with post-GATT patents. Patentees and litigants should take care to identify relevant fact patterns, particularly those in which a patentee has filed successive continuations in a patent family and appears to have crafted claim language specifically directed to products and technologies released in the market long after the patentee's corresponding priority application(s).
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.