Fact-Checking the Assertions of the Parties in Hyatt v. Squires

Gilbert Hyatt is a prolific independent inventor known for his large number of patent applications held up for decades at the U.S. Patent and Trademark Office (USPTO) and the courts. In its decisions in Hyatt v. Hirshfeld, 998 F. 3d 1347 (Fed. Cir. 2021) (Hyatt I) and Hyatt v. Stewart, 148 F. 4th 1376 (Fed. Cir. 2025) (Hyatt II), the Federal Circuit held that he forfeited his patent rights under the prosecution laches doctrine. Under this judge-made doctrine, the extra-statutory charge of applicant’s “unreasonable and unexplained delay in prosecution,” is a cause for forfeiture of the patent right. The court also created for the first time a substantive burden-shifting rule holding that a patent prosecution “delay of more than six years raises a ‘presumption that it is unreasonable, inexcusable, and prejudicial.’” Hyatt I, 998 F. 3d at 1369 (emphasis added). Hyatt argued at the Federal Circuit that the doctrine of prosecution laches cannot be available after the 1952 Patent Act because the statute fully specified prosecution timeliness requirements. He petitioned for certiorari to the U.S. Supreme Court on March 2, 2026, seeking review (Hyatt Pet.). On May 26, 2026, the USPTO filed a Brief in Opposition (USPTO Br.) to Hyatt’s petition, and on June 5, 2026, Hyatt filed his Reply Brief (Hyatt Br.).

This post focuses on the factual assertions made by both parties in their briefings on the scope and level of use of the prosecution laches defense. The historical facts of the judge-made co-pendency law on continuing applications prior to the 1952 Patent Act are presented, and the specific change that authorized them by statute under the 1952 Patent Act is discussed.

1. Contrary to the USPTO’s assertion, the use of prosecution laches defense in recent years is rampant against patents filed post 1995. The USPTO argues that Hyatt’s petition presents a question that “has limited and diminishing importance because the vast majority of pending patent applications and patents in force today postdate the 1995 change in patent term” USPTO Br. at 8. The USPTO explains why in its opinion the “limited and diminishing significance of the question presented provides a further reason to deny review.” Id., at 17. The USPTO contends that “[t]oday, the vast majority of pending applications and patents in force post-date the 1995 amendment. And while petitioner contends (Pet. 31-32) that prosecution laches is frequently invoked, he cites no case in which the Federal Circuit has relied on the doctrine to bar a patent application that was filed after the effective date of the 1995 amendment.” Id., at 17-18. Countering that, Petitioner Hyatt’s Reply asserts: “Hundreds of litigants have asserted prosecution laches in the past few years. Indeed, at least 30 more have done so in the mere three months since Petitioner filed his Petition—with every one of those cases involving patents claiming priority to filing dates after 1995.” Hyatt Br. at 11.

The USPTO’s speculative assertions belie the facts, which rather align closely with Hyatt’s assertions. My recent article on the subject includes Appendices A1-A2 that identify patent infringement cases in which defendants asserted the prosecution laches defense subsequent to the holding of Hyatt I in June 1, 2021. As these Appendices show, such defenses were asserted in at least 424 federal cases with a total across these cases of 1,786 Patents in Suit, all of which were filed after 1995. The affected patents are far more numerous when including the tainted patent “families” of these Patents in Suit.

Appendix A2 separately identifies the cases with prosecution laches defense asserted since Hyatt filed his petition on March 2, 2026. Here too, Hyatt Brief’s assertion of 30 such cases is confirmed exactly and the cases are identified in detail. The USPTO is clearly wrong in its assertion that prosecution laches “has limited and diminishing importance” because these assertions against post-1995 patents are rampant.

The USPTO observed that Petitioner had identified no case in which “the Federal Circuit has relied on the doctrine to bar a patent application that was filed after the effective date of the 1995 amendment.” USPTO Br. at 18. That observation does not answer the relevant question, correct as it may be. The pertinent inquiry is not whether the Federal Circuit has ultimately sustained a prosecution-laches defense against a post-1995 application, but whether the court has treated such applications as legally susceptible to forfeiture under that doctrine. My article shows that the Federal Circuit’s decision in Google LLC v. Sonos, Inc. (Fed. Cir. 2025) demonstrates that it has. The Federal Circuit in this case had not reversed the district court’s legal conclusion that prosecution laches applies to post-1995 applications, and proceeded to analyze Sonos’s post-1995-applied patents under the two-element standard of prosecution laches, which can only apply when considering the prosecution laches defense. No Federal Circuit decision held that prosecution laches was categorically unavailable for such patents, and it is inconceivable that it will, short of Supreme Court abrogation of the doctrine.

Even if the litigation does not reach the determinations on prosecution laches for adjudicating the alleged “unreasonable delay in prosecution,” the initial shift of the burden of proof is onto the patent holder under the Federal Circuit’s six-year “presumption that it is unreasonable, inexcusable, and prejudicial.” That presumption is precedential and applicable broadly—not merely to Petitioner Hyatt.

A more troubling trend I discuss and quantify in my article is the rise in prosecution laches assertions by accused infringers at the International Trade Commission (ITC). The effect at the ITC can be devastating for the domestic U.S. industry. Many of these industries are protected by patents for inventions that required large investments over extended periods to develop, improve, and perfect the inventions. Accordingly, many of those patents issued from continuation-in part (CIP) applications with early priority dates and are more susceptible to the Hyatt I six year presumption of unenforceability. Figure 1 in my article shows the distributions of prosecution time at the USPTO of utility patents asserted at the ITC, showing that 36% of them issued later than six years after their earliest priority date. This is significantly larger share of patents compared to the 30% share of all issued utility patents shown in the figure.

An attack on the U.S. domestic industry can more easily succeed by any foreign goods importer that infringes such U.S. patents, because it can invoke the six-year presumption of unenforceability on contention under the prosecution laches doctrine. This uncorrected Federal Circuit decision can be used as a powerful weapon by foreign adversaries against U.S. industries.

2. The correct facts on pre-1952 patent statutes reveal that they contained no express or implied prosecution timeliness requirements. In its Opposition Brief, the USPTO contends that “the Patent Act does not impose a fixed time period to complete prosecution,” which in its opinion justifies the equitable prosecution laches doctrine after the 1952 Patent Act. USPTO Br. at 12-13. My article shows that the enactment in 1952 of 35 U.S.C. § 120’s limitation of temporal co-pendency of application with the previous parent application constitutes a “statute of limitation,” not previously in the law. To obfuscate this fact, the USPTO mischaracterizes an 1863 judicial decision as if it were pre-1952 statutory provision, contending that the 1952 Patent Act’s timeliness provisions “are merely analogues of similar timing limits that applied under the prior patent laws and have long coexisted with prosecution laches.” USPTO Br. at 14. For support, USPTO’s footnote 2 that follows this contention lists some pre-1952 statutory provisions on applicant response timing, but cited to Godfrey v. Eames, 68 U.S. 317, 325-326 (1863) as to the “co-pendency” provision. However, a Supreme Court decision is not a statutory enactment. At that time, the most critical timeliness requirement of “co-pendency” of applications was judge-made law—not a statutory provision. It is the Court—not Congress—that made up the rule of the “co-pendency” requirement. No statute prior to the 1952 Act provided for anything close to “co-pendency” of applications as a timeliness requirement.

The USPTO’s assertion that the timeliness provisions of the 1952 Patent Act “are merely analogues of similar timing limits that applied under the prior patent laws” is false. That assertion renders invalid its hyperbolic implication that applying equitable doctrines after the 1952 Patent Act is as justified as it was before it. As my article shows, in 1952 Congress occupied the field entirely, crafting elaborate timeliness requirements for co-pendency, leaving no room for the courts or the USPTO to second-guess the policy balance.

Post-1995 Patents are Threatened

The reality of prosecution laches assertions is that they are rampant against patents filed post 1995. It contravenes the statute and therefore the question before the Supreme Court is not an outlier circumstance—its scope is widespread and patents filed after 1995 are being threatened with forfeiture.

For more details, see my article on this subject at SSRN. Additional details can be found in my Amicus Brief in this case, where I also show why Section 120 precludes the application of the equitable doctrine of prosecution laches.

Image Source: Deposit Photos
Author: alexskopje
Image ID: 30864475