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How to avoid prosecution laches: a checklist for continuation practice

Updated Oct 23, 2026

Short answer

Prosecution laches needs two things: unreasonable, unexplained delay in prosecution, and prejudice to the party raising it. It still applies in extreme cases: Hyatt v. Stewart (Fed. Cir. 2025) was affirmed, and cert was denied on June 29, 2026. Steady prosecution, documented reasons and supported claims may keep that risk low.

What is prosecution laches?

It is an equitable defense. It 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” (Cancer Research, quoted in Google v. Sonos, slip op. at 15).

The Federal Circuit breaks it into two elements (PMC v. Apple, 2023):

the delay in prosecution was unreasonable and inexcusable under the totality of circumstances; and
the party raising the defense suffered prejudice attributable to the delay.

Prejudice means the party raising the defense or others “invested in, worked on, or used the claimed technology during the period of delay” (PMC). The USPTO can also raise the defense against pending applications in a § 145 action (Hyatt v. Hirshfeld, 2021).

What have the courts held since 2021?

Leading Federal Circuit prosecution laches decisions, 2021–2025
Case	Result	Why it matters
Hyatt v. Hirshfeld, 998 F.3d 1347 (2021)	Vacated and remanded.	Laches is available to the USPTO in a § 145 action. It did not hold the applications unenforceable.
Personalized Media v. Apple, 57 F.4th 1346 (2023)	Affirmed unenforceability.	An issued patent was lost to laches. Cert denied Oct. 10, 2023.
Hyatt v. Stewart, 148 F.4th 1376 (2025)	Affirmed for the USPTO.	Cert denied June 29, 2026; rehearing denied Sept. 4, 2026.
Google v. Sonos, No. 2024-1097 (Aug. 28, 2025)	Reversed laches. Nonprecedential.	No prejudice: the specification published in 2013, before Google’s asserted investment.

In Sonos, the court limited its discussion to prejudice. It did not decide whether the roughly 13-year delay was unreasonable. Its key line: “Google cannot be prejudiced by incorporating into its products a feature that was publicly disclosed in a patent application prior to its investment” (slip op. at 16). As a nonprecedential decision, it illustrates the point rather than establishing it. See the Sonos v. Google explainer.

Is claiming a competitor’s product itself a laches risk?

Not by itself. The Sonos court cited Liebel-Flarsheim (Fed. Cir. 2004): “[I]t is not improper for an applicant to broaden his claims during prosecution in order to encompass a competitor’s products, as long as the disclosure supports the broadened claims” (slip op. at 16).

The risk sits in the timing and the record: how long the claims waited, why, and what others did meanwhile. For the wider playbook, see continuation strategy for competitor products.

Checklist: keeping a pending family defensible

For practitioners keeping families pending and filing continuations aimed at products on the market. Each item may make delay easier to explain. None is a rule from a court.

8 items. Tick each for the family under review. Ticks are not saved.

1. File continuations in the ordinary course, before the parent issues.
Refiling is reasonable when it “is not unduly successive or repetitive” (Hyatt v. Hirshfeld, slip op. at 22, summarizing Symbol Technologies). A continuation filed as part of a planned program for the family is easier to explain than one revived years later.
2. Respond to every Office action on time and on the merits.
Each response should move the application toward allowance or appeal. A record of steady progress is the simplest answer to a delay argument.
3. Avoid serial refiling without prosecution progress.
Before each new filing, write down what it adds: new claims, a new argument, new evidence. A chain of continuations that re-presents the same claims, with no progress, is hard to explain later.
4. Document the business reason for each filing and its timing.
In Hyatt, meeting the statutory requirements and following the rules were not, on that record, enough; the court required “a legitimate, affirmative reason for his delay” (slip op. at 41). A short file memo made at the time is better evidence than a reconstruction years later.
5. Keep every new claim supported by the as-filed specification, with paragraph citations.
Broadening to encompass a competitor’s product is proper “as long as the disclosure supports the broadened claims” (Liebel-Flarsheim, quoted in Sonos, slip op. at 16). See the written description explainer.
6. Don’t sit on claims for years after learning of a product.
Prejudice turns on investment and work during the period of delay (PMC). The longer claims wait after a product is known, the more of that a defendant may point to. Note when the specification became public: in Sonos, its 2013 publication defeated prejudice.
7. Consider Track One to shorten pendency.
Request it when the continuation is filed: $4,515 plus a $150 processing fee (large entity), at most 4 independent and 30 total claims (37 CFR 1.102(e)). The FY2026 dashboard shows 4.9 months from grant of the request to final disposition (USPTO). See Track One for continuations.
8. Track the earliest benefit date and the surcharge dates.
The earliest benefit date shows how long the family has been pending. It also sets the continuing application fee: $2,700 after 6 years and $4,000 after 9 (large entity) (CAF Guide). Calculate the dates.

Which members of the family are still pending?

The free continuation window checker reads public USPTO records. It shows which family members are pending, the earliest benefit date and the surcharge dates: items 1 and 8 above.

What can a checklist not do?

Laches is decided on the totality of the circumstances, after the fact, by a court. A checklist cannot tell you whether a given delay is reasonable. It can help build a record that shows why each filing was made and when.

Practitioner judgment

Whether to file, when, and with which claims is a decision for your registered patent practitioner. This page is general information, not legal advice.

Informational only, not legal advice. Have a registered patent practitioner review before filing.

Questions about prosecution laches

What is prosecution laches?

An equitable defense. It may render a patent unenforceable when it 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 (Cancer Research, quoted in Google v. Sonos, 2025). The party raising it must also show prejudice.

Did Sonos v. Google remove the laches risk for late continuations?

No. The August 2025 decision is nonprecedential. It reversed the laches ruling because Google failed to prove prejudice, since the specification had published in 2013, before Google’s asserted investment. It did not decide whether the roughly 13-year delay was unreasonable.

Did Hyatt v. Hirshfeld hold Hyatt’s applications unenforceable?

No. The 2021 decision held that the USPTO may raise prosecution laches in a § 145 action, then vacated and remanded so Hyatt could present evidence. On remand the USPTO prevailed, and the Federal Circuit affirmed in Hyatt v. Stewart, 148 F.4th 1376 (2025). The Supreme Court denied cert on June 29, 2026.

Is it improper to file a continuation aimed at a competitor’s product?

Not in itself. The Federal Circuit has said it is not improper to broaden claims during prosecution to encompass a competitor’s products, as long as the disclosure supports the broadened claims (Liebel-Flarsheim, 2004, quoted in Sonos, 2025). Support in the as-filed specification is the condition.

How is prejudice shown?

By proof that the party raising the defense or others invested in, worked on, or used the claimed technology during the period of delay (Personalized Media v. Apple, 2023). In Sonos, the court found no prejudice where the feature was publicly disclosed in a published application before the investment.

Does following the checklist make a family safe from laches?

No checklist can. Laches is decided on the totality of the circumstances. The checklist lists practices that may make delay easier to explain. Whether a filing plan is reasonable is a judgment for your registered patent practitioner.

Sources

Quotes checked Oct 23, 2026 against the slip opinions linked above. Liebel-Flarsheim is quoted as it appears in Sonos.

Planning a continuation for a product already on the market?

Send the application number and a link to the product. We check whether the pending specification may support claims covering it, with paragraph citations and the dates that matter, for review by your registered patent practitioner. The first reviews are free.