IP UPDATE
Exploring the latest in intellectual property law
IP UPDATE
Exploring the latest in intellectual property law
Results for "Patent"
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Construing claims to fit the brand

by | Jul 9, 2026 |

The US Court of Appeals for the Federal Circuit affirmed a district court’s claim construction and grant of a preliminary injunction, concluding that an accused infringer’s proposed construction would have produced the “highly improbable” result of excluding the patentee’s Orange Book-listed drug from the scope of the asserted claims. Otsuka America Pharmaceutical, Inc. v. Hetero Labs Limited, Case No. 25-2016 (Fed. Cir. July 1, 2026) (Bryson, Stoll, JJ.) (Dyk, J., dissenting in part)

Otsuka sued Hetero Labs, alleging that Hetero Labs’ generic drug product would infringe Otsuka’s patent rights. Otsuka moved for a preliminary injunction to prevent Hetero Labs from entering the market. The district court granted the motion, concluding that Otsuka was likely to succeed on its infringement claim. Hetero Labs appealed, arguing that the district court erred in construing the asserted claims.

The central dispute concerned how to calculate the patent’s claimed weight ratio. The representative claim requires administering dextromethorphan in combination with quinidine, with the proviso that the “weight to weight ratio of dextromethorphan to quinidine is 1:0.5 or less.” The district court construed “dextromethorphan” and “quinidine” to include their pharmaceutically acceptable salts. Under that construction, the claimed ratio is calculated using the full weight of the compounds as administered – for example, the full weight of dextromethorphan hydrobromide rather than only the dextromethorphan active moiety. Hetero Labs, by contrast, argued that when the compounds are administered as salts, the ratio must be calculated using only the weight of the active moieties.

The Federal Circuit affirmed the district court’s construction, concluding that the intrinsic evidence supported construing “dextromethorphan” and “quinidine” to include both the free base compounds and their pharmaceutically acceptable salts. The Court found that the patent claims, specification, and prosecution history consistently used those terms to encompass the compounds in the form in which they are administered. The Court also found that extrinsic evidence supported its construction. Relying in part on its 2007 decision in Osram GmbH v. ITC, the Court explained that Hetero Labs’ proposed construction would produce the “highly improbable” result of excluding Otsuka’s Orange Book-listed Nuedexta product – the very product the patent was intended to protect – from the scope of the claims. The Court also rejected Hetero Labs’ indefiniteness argument, concluding that the claims were not rendered indefinite simply because they encompassed formulations using either free bases or pharmaceutically acceptable salts.

Judge Dyk, dissenting in part, concluded that the district court’s construction was inconsistent with both the intrinsic evidence and the purpose of the claimed invention. According to Judge Dyk, the invention depended on maintaining a specific ratio of dextromethorphan to quinidine to ensure that:

  • Dextromethorphan achieved a therapeutic effect
  • Quinidine slowed the metabolism of dextromethorphan
  • Patients were not exposed to excessive amounts of quinidine

In his view, calculating the claimed ratio using the full weight of pharmaceutically acceptable salts rather than only the active moieties distorted that relationship by incorporating the weight of carrier ions that have no therapeutic significance. Judge Dyk also disagreed with the majority’s reliance [...]

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Unintentional delay: USPTO shortens threshold for additional information requirement

by | Jul 1, 2026 |

On June 24, 2026, the United States Patent and Trademark Office (USPTO) revised its practice of requiring additional information for certain petitions based on unintentional delay and changed the conditions under which the corresponding higher petition fee applies. The new rule is effective August 13, 2026.

In March 2020, the USPTO clarified that additional information would generally be required for petitions based on unintentional delay in the following three circumstances:

  • A petition to revive an abandoned application filed more than two years after the application became abandoned.
  • A petition to accept a delayed maintenance fee payment filed more than two years after the patent expired for nonpayment.
  • A petition to accept a delayed priority or benefit claim filed more than two years after the priority or benefit claim was due.

The USPTO required petitioners to provide additional information when a petition was filed more than two years after the relevant deadline. The additional information was intended to establish the facts and circumstances surrounding the entire period of delay and demonstrate that the entire delay was “unintentional.” The USPTO reasoned that the two-year threshold would reduce uncertainty and unpredictability concerning patent rights.

Under the new rule, the USPTO has shortened the threshold for requiring additional information from two years to one year. The USPTO explained that the one-year threshold will further increase certainty and predictability concerning patent rights by requiring applicants and patentees to provide an adequate explanation establishing that the entire delay was unintentional. According to the USPTO, such an explanation “safeguards a patentee’s rights by establishing on the record that the delay was unintentional, and protects the public by prohibiting revival, reinstatement, entry of a benefit or priority claim, or excuse of delay” when a party cannot establish that the delay was unintentional. The USPTO also explained that the revised threshold will promote efficiency by encouraging applicants to monitor their patent files and promptly address errors.

The new rule extends this one-year threshold to petitions seeking to excuse an applicant’s failure to act within prescribed time limits under the Hague Agreement in connection with international design applications. The USPTO emphasized, however, that it retains discretion to require additional information whenever there is a question whether a delay was unintentional, regardless of the length of the delay.

Because the revised rule increases the evidentiary requirements and the cost of reviewing petitions filed after an extended delay, the USPTO also revised the threshold for when the higher petition fee applies. Under the new rule, the higher fee applies to petitions filed more than one year after the applicable deadline, rather than more than two years after the deadline. According to the USPTO, applying the higher fee at the one-year threshold will further encourage applicants to file petitions promptly, benefiting applicants by reducing delays in the examination process and promoting greater certainty and predictability regarding patent rights.

Practice note: Petitioners filing a petition to revive an abandoned application more than one year after the application became abandoned, a petition to [...]

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Compound errors: Written description, not typographical error analysis, controls priority claim

by | Jul 1, 2026 |

The US Court of Appeals for the Federal Circuit affirmed summary judgment that the asserted patent was invalid as anticipated because the provisional application to which it claimed priority did not provide adequate written description support for the claimed compound. The Court explained that the proper inquiry was whether the provisional demonstrated possession of the later-claimed subject matter, not whether a discrepancy in the provisional could be characterized as an obvious typographical error. Enanta Pharmaceuticals, Inc. v. Pfizer Inc., Case No. 25-1427 (Fed. Cir. June 23, 2026) (Lourie, Bryson, Chen, JJ.)

Enanta owns a patent direct to coronavirus inhibitors. The patent claimed priority to a July 20, 2020, provisional application. In April 2021, before Enanta filed a nonprovisional application correcting what it later characterized as a typographical error, Pfizer publicly disclosed the compound that ultimately became part of its COVID-19 treatment, Paxlovid®.

The dispute centered on a structural limitation defining an alkyl substituent. The provisional disclosed NHC(O)-C2-C12-alkyl while the asserted patent claimed NHC(O)-C1-C12-alkyl. According to Enanta, the “C2” designation in the provisional was an obvious drafting error that a person of ordinary skill in the art would recognize and mentally correct.

The district court granted summary judgment that the patent was anticipated because the asserted claims were not entitled to the provisional application’s filing date. Enanta appealed.
While the Federal Circuit affirmed, it clarified that the district court framed the issue incorrectly. Rather than asking whether a court could correct an alleged error in the provisional, the proper question was whether the provisional itself provided sufficient written description support for the later-claimed invention.

In clarifying the appropriate inquiry, the Federal Circuit rejected Enanta’s reliance on cases addressing correction of errors in issued patents and decisions concerning genus-species written description issues, explaining that those authorities did not govern the priority analysis presented here. Nor could the Court simply construe the provisional to correct the alleged mistake because the disclosure was subject to reasonable debate.

Applying the written description standard, the Federal Circuit concluded that “C2 is simply different from C1.” Because the provisional disclosed only the C2 structure, it did not demonstrate that the inventors possessed the later-claimed C1 embodiment as of the provisional filing date. The Court also found Enanta’s expert testimony insufficient to create a genuine issue of material fact, explaining that generalized opinions regarding carbon chain nomenclature and drafting errors elsewhere in the specification did not establish written description support for the specific claimed limitation.

Because the asserted claims were not entitled to the provisional application’s priority date, Pfizer’s intervening public disclosure constituted anticipatory prior art, rendering the patent invalid.



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Not so bulletproof: USPTO rejects discretionary denial across seven IPR petitions

by | Jun 25, 2026 |

The United States Patent and Trademark Office (USPTO) denied a patent owner’s request for discretionary denial of seven inter partes review (IPR) petitions, further providing guidance on the factors to consider when exercising discretionary review. The decision was designated informative on June 15, 2026. Tesla, Inc. v. Bulletproof Property Mgmt., LLC, IPR2026-00204; -00205; -00219; -00222; -00227; -00228; -00229 (USPTO, June 15, 2026)

The USPTO Director previously issued a short notice referring Bulletproof’s (the patent owner) requests for discretionary denial and Tesla’s oppositions to them for merits consideration. Unlike many prior discretionary denial decisions that were issued with limited or no analysis, this decision directly addressed the parties’ arguments and explained why each weighed against discretionary denial of Bulletproof’s petitions.

First, Bulletproof argued that institution should be denied because of parallel district court litigation. The USPTO Director rejected that argument, noting that a trial date had not been set and that Tesla stipulated it would not pursue any invalidity grounds that were raised or reasonably could have been raised in the IPRs. According to the USPTO, the stipulation reduced the risk of duplicative proceedings and inconsistent outcomes, making institution a more efficient use of party and agency resources.

Second, Bulletproof further argued that institution should be denied because a key prior art reference had previously been presented to the USPTO. Although the reference appeared in information disclosure statements submitted during prosecution of related child applications, it was not presented during examination of the application from which the challenged patents claimed priority. The USPTO agreed with Tesla that the examiner had effectively overlooked the reference and that Tesla had demonstrated that the USPTO erred in a manner material to patentability.

Third, Bulletproof contended that settled expectations favored denial. The USPTO disagreed, finding no meaningful settled expectations given that the challenged patents were issued less than two years earlier. The relatively brief period between issuance and filing the petitions weighed against discretionary denial.

Lastly, the USPTO found Tesla’s evidence that the accused products are manufactured in the United States persuasive. Although Bulletproof asserted that between one-quarter and one-third of the products’ components originated abroad, it provided no supporting evidence. The USPTO’s analysis is consistent with its March 11 memorandum identifying factors relevant to institution decisions, including the extent to which the challenged products are manufactured domestically.

Practice note: Over the past year, about one in four petitions for institution survive the USPTO Director’s discretionary denial review. Denying Bulletproof’s petition for review of an institution decision underscores the USPTO’s focus on efficiency, avoidance of duplicative proceedings, and domestic manufacturing considerations when evaluating requests for discretionary denial. Institution petitioners may strengthen their position by demonstrating that institution will promote efficient resolution of validity issues, offering broad litigation stipulations where appropriate, and presenting evidence of US-based manufacturing activities.



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Tick tock: Related trade secrets have single accrual date under DTSA statute of limitations

by | Jun 11, 2026 |

The US Court of Appeals for the Federal Circuit reversed a judgment awarding damages and a permanent injunction, finding that the plaintiff’s trade secret misappropriation claims were barred by the statute of limitations under the Defend Trade Secrets Act (DTSA). Insulet Corp. v. EOFlow, Co. Ltd., Case No. 25-1807 (Fed. Cir. May 28, 2026) (Dyk, Reyna, JJ.) (Prost, J., dissenting).

Insulet manufactures the Omnipod, an adhesive wearable insulin patch pump currently sold in 25 countries. EOFlow developed a competing product, the EOPatch 2, marketed in Europe and South Korea. On August 3, 2023, Insulet filed suit against EOFlow alleging trade secret misappropriation under the DTSA and patent infringement.

The misappropriation allegedly occurred when EOFlow hired several former Insulet employees to develop the EOPatch 2. The employees included Steve DiIanni, former director of mechanical engineering at Insulet, who possessed “detailed technical information” about the Omnipod. Between March and May 2018, DiIanni provided EOFlow with computer-aided design (CAD) files and information regarding the Omnipod’s soft cannula and occlusion-detection algorithm.

The district court bifurcated the DTSA and patent claims. At trial on the DTSA claims, the jury found misappropriation of four trade secrets, including the Omnipod CAD files, and concluded that none of Insulet’s claims were barred by the statute of limitations. The jury initially awarded $170 million in compensatory damages and more than $280 million in exemplary damages. These amounts were reduced to $26 million and $34 million, respectively, with the district court’s grant of a permanent injunction. Insulet’s patent claims were dismissed without prejudice.

On appeal, Insulet moved to transfer to the Court of Appeals for the First Circuit. The Federal Circuit denied the motion, concluding that it retained jurisdiction because the dismissal of the patent claims functioned, at least in part, as a dismissal with prejudice, since the statute of limitations expired with respect to certain alleged acts of patent infringement. The Court then addressed two issues under the DTSA statute of limitations: when the statute of limitations begins to run and whether related trade secrets are subject to a single accrual date.

On the first issue, the parties disputed the applicable standard. EOFlow argued that the statute of limitations began to run under an inquiry-notice standard while Insulet contended that the Supreme Court’s 2010 decision in Merck & Co. v. Reynolds required application of a discovery standard under which the limitations period begins when the plaintiff discovers or reasonably should have discovered the facts underlying its claim. The Federal Circuit declined to decide which standard governed, concluding that Insulet’s claims were time-barred even under the more demanding Merck standard. Applying an access-plus-similarity framework, the Court found that, before the critical date, Insulet knew or should have known that EOFlow had access to its trade secrets through a former Insulet employee, and possessed sufficient information regarding similarities between the EOPatch 2 and Insulet’s trade secret technology to plead a misappropriation claim.

On the second issue, for which there was no controlling First Circuit authority, the Federal Circuit determined that the [...]

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AIA reviews: An alternative to litigation, not a second chance

by | May 28, 2026 | ,

Addressing the scope of discretionary institution under the America Invents Act (AIA), the United States Patent and Trademark Office (USPTO) denied institution of inter partes review (IPR), concluding that the petitioner was attempting to use the Patent Trial & Appeal Board as a “second bite at the apple” after unsuccessfully litigating substantially similar invalidity issues in district court, contrary to the AIA’s purpose of providing a streamlined alternative to litigation. Magnolia Medical Technologies, Inc. v. Kurin, Inc., IPR2026-00097, Paper 17 (Director May 14, 2026).

Magnolia challenged the validity of Kurin’s patent directed to a blood-testing device in district court. After the district court excluded Magnolia’s invalidity expert based on disclosure deficiencies related to claim construction and a jury subsequently found the patent not invalid, Magnolia filed an IPR petition asserting substantially similar anticipation and obviousness grounds. The Director denied institution, concluding that Magnolia had already had a full and fair opportunity to litigate those issues in district court and was improperly attempting to relitigate them before the Board.

The Director explained that Congress created IPRs and post-grant reviews (PGRs) under the AIA to provide streamlined and cost-effective alternatives to district court litigation, not to facilitate repetitive validity challenges or expand parallel litigation. The decision noted that, in practice, many petitioners pursue AIA review alongside district court litigation, sometimes asserting overlapping invalidity theories or taking inconsistent positions across forums, thereby increasing costs and burdening both patent owners and the USPTO.

The Director further emphasized that AIA proceedings serve broader public-interest objectives beyond resolving private disputes, including promoting efficiency, fairness, predictability, and the integrity of the patent system. In exercising discretionary institution authority, the USPTO considers factors such as examiner error, inconsistent positions across forums, settled expectations, and whether institution would represent an appropriate use of USPTO resources.

Applying those principles, the Director concluded that Magnolia’s petition fell outside the intended purpose of AIA review because Magnolia was not using the Board as an alternative forum for resolving validity disputes, but instead to relitigate substantially similar invalidity theories after an unfavorable outcome in district court. The Director emphasized that Magnolia had already contested validity in district court using anticipation and obviousness grounds similar to those asserted in the petition and that the parties had expended substantial resources litigating those issues.

The Director rejected Magnolia’s argument that institution was warranted because no tribunal had adjudicated the merits of its anticipation and obviousness theories after the district court excluded its expert testimony. According to the Director, Magnolia had a full and fair opportunity to litigate those issues, and the exclusion of its expert resulted from deficiencies within Magnolia’s control. Permitting institution under those circumstances, the Director explained, would improperly allow Magnolia to obtain a “second bite at the apple” before the USPTO.

In discussing the public-interest considerations that inform discretionary institution decisions, the Director highlighted several precedential and informative decisions addressing issues such as substantial examiner error, inconsistent positions across forums, foreign sovereign petitioners, and settled expectations. The Director explained that these decisions reflect [...]

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Invalidity alone does not render a case exceptional

by | May 28, 2026 |

Addressing fee shifting under 35 U.S.C. § 285 and sanctions under 28 U.S.C. § 1927, the US Court of Appeals for the Federal Circuit affirmed in part and reversed in part a judgment dismissing a patent infringement complaint and awarding attorneys’ fees and costs, finding that the weakness of the plaintiff’s position, without more, did not justify a finding of exceptionality, and that counsel’s lack of diligence did not rise to the bad-faith conduct required for sanctions. mCom IP, LLC v. City National Bank of Florida, Case No. 24-2089 (Fed. Cir. May 15, 2026) (Dyk, Mayer, Taranto, JJ.)

mCom IP sued City National Bank of Florida in September 2023, asserting a patent directed to systems and methods for integrating financial institutions’ “e-banking touch points,” such as ATMs and online banking portals. Earlier that year, an inter partes review (IPR) initiated by Unified Patents resulted in all but four claims being found unpatentable as obvious under 35 U.S.C. § 103. mCom’s district court complaint asserted those four surviving claims.

The district court struck mCom’s initial complaint as a “shotgun pleading” and dismissed the amended complaint with prejudice for failure to state a claim. It also concluded that the asserted claims were invalid on the same obviousness grounds addressed in the IPR and awarded attorneys’ fees under § 285, finding the case exceptional, and imposed sanctions under § 1927 based on counsel’s litigation conduct. mCom appealed.

The Federal Circuit affirmed the dismissal but reversed the fee award and sanctions. The Court addressed two issues: whether the case was “exceptional” under § 285 and whether counsel had unreasonably and vexatiously multiplied the proceedings under § 1927.

Under § 285, a case is exceptional if it “stands out” based on the substantive strength of a party’s position or the unreasonable manner of litigation. The Federal Circuit rejected each basis relied on by the district court.

First, although the asserted claims were ultimately found invalid, the Federal Circuit emphasized that invalidity alone does not render a case exceptional. Rather, awarding fees requires a showing that the claims were “unusually or extraordinarily weak.” That standard was not met here where the asserted claims survived IPR and carried a presumption of validity, and where the burden of proof for invalidity in district court remains higher than in IPR.

Second, the Federal Circuit found that pleading deficiencies did not support exceptionality. The initial complaint’s defects were “purely formal,” and the amended complaint’s failure to state a claim, without more, did not render the overall litigation conduct unreasonable.

Third, the Federal Circuit rejected reliance on City National’s purported license defense, noting that no license had been established on the record.

Finally, the Federal Circuit found insufficient support for the contention that mCom pursued nuisance-value settlements, explaining that City National failed to provide evidence regarding settlement amounts or to tie prior litigation to the patent at issue.

The Federal Circuit also reversed the sanctions imposed under § 1927. Applying Eleventh Circuit law, the Federal Circuit explained that sanctions require conduct [...]

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Chill out: Numerical claim terms properly limited by industry standards

by | May 21, 2026 |

The US Court of Appeals for the Federal Circuit affirmed a noninfringement finding, concluding that a claim limitation reciting a pH range having only a lower limit referred to pH measured at standard temperature in the art. The Court also found that prosecution history estoppel and the disclosure-dedication rule foreclosed reliance on the doctrine of equivalents to capture a pH below the express lower limit. Actelion Pharms. Ltd. v. Mylan Pharms. Inc., Case No. 24-1641 (Fed. Cir. May 13, 2026) (Reyna, Taranto, Stoll, JJ.)

Actelion owns patents covering lyophilized epoprostenol formulations used to treat cardiovascular disease. Epoprostenol is unstable in water because acidic conditions catalyze its degradation. The patents sought to improve stability by manufacturing highly basic bulk solutions, thereby producing freeze-dried formulations that remained stable after reconstitution in typical intravenous fluid. The asserted claims recite bulk solutions having a pH “of 13 or higher” or “greater than 13.”

Mylan sought approval to market a generic version of Actelion’s Veletri® product and was sued under 35 U.S.C. § 271(e)(2). The district court construed “a pH of 13 or higher” to mean “a pH of 12.98 or higher.”

It was undisputed that Mylan’s bulk solution measured below a pH of 12.98 at standard temperature (25±2°C). Actelion nevertheless contended that infringement existed because the solution exceeded pH 13 at lower temperatures during refrigerated manufacturing.

The district court disagreed, finding that the claim term “a pH of 13 or higher” referred to a pH measured at a temperature standard in the field, and that therefore Mylan did not literally infringe. The district court further ruled that Actelion was barred from asserting and had not proved infringement under the doctrine of equivalents. Actelion appealed.

The Federal Circuit agreed with the district court that a person of ordinary skill would interpret the claimed pH values as measurements taken at standard temperature, absent an express indication otherwise. Although the claims did not specify measurement conditions, the specification consistently treated pH values as standard-temperature measurements. The Court emphasized that the specification compared results across pH levels without suggesting temperature-dependent variation and described an “alkaline environment” as “pH > 7,” a statement accurate only at standard temperature.

The Federal Circuit found that extrinsic evidence reinforced that understanding. The United States Pharmacopeia and expert testimony established that, in pharmaceutical formulations, pH is ordinarily measured at 25±2°C unless otherwise specified. The Court found no clear error in the district court’s factual findings on industry practice.

Because Mylan’s product failed to meet the pH limitation under that standard, the Federal Circuit affirmed the finding of no literal infringement.

The Federal Circuit also rejected Actelion’s doctrine of equivalents theory. During prosecution, Actelion amended the claims from “greater than 12” to “a pH of 13 or higher” after the examiner recognized unexpected results at pH 13 but not at pH 12. The Court found that this narrowing amendment gave rise to prosecution history estoppel, barring Actelion from recapturing lower pH values through equivalence.

Separately, the Federal Circuit applied the disclosure-dedication rule. The patents [...]

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Appellate deference: Reinforcing limits on reweighing evidence

by | May 21, 2026 |

Clarifying the proper scope of appellate review, the US Court of Appeals for the Federal Circuit affirmed an International Trade Commission final determination in full. The Court upheld the scope of the exclusion of only certain accused products and permitted importation of redesigned versions, concluding that the Commission correctly viewed the evidence and claim terms. Bissell, Inc. v. ITC, Case No. 24-1509 (Fed. Cir. May 11, 2026) (Moore, Taranto, Stoll, JJ.)

Bissell initiated a Section 337 investigation alleging that Tineco Intelligent imported wet/dry surface-cleaning devices that infringed Bissell’s patents. Following an evidentiary hearing, the administrative law judge (ALJ) found infringement of Tineco’s original products and recommended exclusion but concluded that Tineco’s redesigned products did not infringe and therefore fell outside the scope of relief.

The Commission affirmed the ALJ’s determination, which resulted in a limited exclusion order directed to the infringing products only. Both parties appealed.

Bissell challenged the finding that Tineco’s redesigned products did not literally infringe a limitation requiring that “the battery charging circuit is disabled” during the “self-cleaning mode . . . and remains disabled during the . . . cleanout cycle.” Tineco modified its products so that some battery charging did occur during a “self-cleaning mode,” but battery charging was disabled for most of the cleaning cycle. Before the ALJ, Bissell’s expert opined that infringement of this claim essentially only required a period in which self-cleaning occurred and while the battery charger was disabled. The ALJ rejected Bissell’s theory, determining that the claim required the battery charger to “remain[] disabled during the . . . cleanout cycle.”

According to Bissell, the ALJ’s conclusion amounted to improper claim construction. The Federal Circuit disagreed, finding that the ALJ had merely applied the plain and ordinary meaning of the claim term. As Bissell had not disputed that the ALJ’s findings were supported by substantial evidence, the Federal Circuit affirmed these findings.

Tineco cross-appealed the ALJ’s determination that Bissell’s domestic industry products satisfied the disabled battery limitation. According to Tineco, the evidence was inadequate to support the ALJ’s determination because the source code that Bissell’s expert relied on was never produced during the Commission trial.

The Federal Circuit found that Bissell’s expert testimony was sufficient under Federal Rule of Evidence 703, which permits experts to rely on facts or data they have been made aware of or personally observed, even if those materials are not themselves admissible, as long as they are of a type reasonably relied upon in the field. The Court emphasized that neither party disputed that experts in this context routinely rely on source code to assess infringement. The Court further concluded that substantial evidence supported the ALJ’s determination, highlighting that:

  • The source code had been produced during discovery.
  • The expert’s opinions were not conclusory.
  • Tineco did not meaningfully test the testimony through cross-examination or offer competing expert analysis.
  • The ALJ’s findings were independently corroborated by a Bissell internal document admitted at trial.

Practice note: Where the Commission uses the “face of the claim to [...]

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Words of approximation require more precision after narrowing amendments

by | May 14, 2026 |

The US Court of Appeals for the Federal Circuit affirmed a judgment of indefiniteness, concluding that the use of the term “about” to define a critical pH limitation failed to inform skilled artisans of claim scope with reasonable certainty under 35 U.S.C. § 112. Enviro Tech Chemical Services, Inc. v. Safe Foods Corp., Case No. 24-2106 (Fed. Cir. May 4, 2026) (Lourie, Prost, Burroughs, JJ.)

Enviro Tech owns a patent that claims a method for treating poultry during processing to increase the weight of the poultry by using peracetic acid. Each claim in the patent requires the step of altering the pH of the peracetic-acid-containing water to “a pH of about 7.6 to about 10” by adding an alkaline source.

During claim construction, the district court concluded that the term “about” was indefinite, finding that the intrinsic evidence did not inform a skilled artisan as to the scope of the term “about” with reasonable certainty. Enviro Tech appealed.

The Federal Circuit has long held that words such as “about” and “approximately” may be appropriately used to avoid a strict numerical boundary to the specified parameter. However, when a word of approximation is used, the parameter’s range must be reasonably certain based on the “technological facts of the particular case” and considering the claims, specification, prosecution history, and extrinsic evidence.

Starting with the claims, the Federal Circuit found that they failed to provide meaningful guidance on how far below a pH of 7.6 or above a pH of 10 the peracetic-acid-containing water could fall and still satisfy the limitation. Although the parties agreed that “about” ordinarily means “approximately,” the Court concluded that substituting one term for the other does not clarify the permissible deviation from the claimed range or otherwise inform a skilled artisan of the scope of the claims.

The Federal Circuit next turned to the specification, finding that it also failed to define the scope of “about” with reasonable certainty because it provided inconsistent guidance on acceptable pH deviations. Although the specification disclosed experiments where Enviro Tech only proceeded when the measured pH was within 0.3 of the target, the specification also described instances where Enviro Tech continued experiments despite larger deviations, including a large scale poultry processing test with pH variances of up to 0.5. Given these unexplained exceptions (particularly in a commercially significant real world setting) the Court found that the 0.3 threshold could not be treated as a reliable boundary for “about.” Thus, the Court found that the specification’s conflicting examples left skilled artisans without clear notice of the claimed scope.

Turning to the prosecution history, the Federal Circuit found that Enviro Tech treated the term “about” inconsistently. For instance, in one office action response, Enviro Tech argued that “a peracetic acid solution at the lower end of the claimed range, pH 7.6,” would not have been obvious over the prior art, notably omitting the word “about.” Yet on the very next page, Enviro Tech asserted that “a step of adjusting the pH to the range [...]

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