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From genus to subgenus: When written description and enablement demand more

by Kyle Sorenson, PhD | Dec 11, 2025 | Patents

The US Court of Appeals for the Federal Circuit reversed a district court’s denial of a motion for judgment as a matter of law (JMOL), finding that the patent specification failed to provide an adequate written description to practice the full scope of the claimed invention. Seagen Inc. v. Daiichi Sankyo Co., Ltd., Case Nos. 2023-2424; 2024-1176 (Fed. Cir. Dec. 2, 2025) (Lourie, Reyna, Chen, JJ.)

In 2020, Seagen sued Daiichi for infringing its patent covering antibody-drug-conjugates (ADCs). The patent claims priority to a 2004 application that broadly describes ADCs. The application lists 83 possible amino acids and includes more than 47 million possible tetrapeptide combinations. A Texas jury sided with Seagen, finding that Daiichi willfully infringed at least one claim, and awarded more than $41 million in damages plus an 8% running royalty. The district court denied Daiichi’s post-trial motion for JMOL and entered final judgment. Daiichi appealed.

Daiichi argued that no reasonable jury could have found that the 2004 application provided an adequate written description that would enable a skilled artisan to make and use the full scope of the claimed treatment. The Federal Circuit agreed, finding that the 2004 application did not provide written description support for a narrow Gly/Phe-only tetrapeptide subgenus. The application disclosed an enormous genus (approximately 47 million potential tetrapeptides derived from 83 amino acids) without identifying or singling out any tetrapeptide composed exclusively of Gly and Phe. The Court found that the mere appearance of Gly and Phe somewhere within the large list of amino acids was insufficient. The Court determined that Seagen’s claimed 81-member subgenus was merely an infinitesimal fraction of the millions of encompassed species, and that nothing in the 2004 disclosure singled out or directed a skilled artisan toward the Gly/Phe-only species claimed in the patent. Testimony from the named inventors also confirmed that, as of the application’s priority date, they had never contemplated a treatment using only the 81 tetrapeptides later claimed in the patent.

The Federal Circuit also found that the patent did not enable a skilled artisan to make and use the full scope of the claimed ADCs without undue experimentation. The district court had construed “D is a drug moiety” to encompass any drug, and the claims required that the drug be intracellularly cleaved in a patient. Together, these elements defined an extraordinarily broad genus of ADCs: any drug moiety paired with the required intracellular cleavage.

The specification, however, did not identify any common structural features predictive of intracellular cleavage across all possible drug-linker-antibody combinations. Instead, the evidence showed that ADC behavior was highly unpredictable, and scientists had to conduct assays to determine whether a given ADC satisfied the functional limitation.

Under long-standing Federal Circuit precedent where a patent disclosure requires researchers to conduct the undue experimentation doctrine, it does not satisfy the written description requirement. Because skilled artisans would need to evaluate enormous numbers of ADC permutations to determine whether they achieved the claimed intracellular cleavage, the patent failed the enablement requirement.

IPR estoppel doesn’t extend to ongoing ex parte reexamination

by Jolie B. Schenerman | Dec 11, 2025 | Patents

The US Court of Appeals for the Federal Circuit affirmed a decision by the Patent Trial & Appeal Board, concluding that inter partes review (IPR) estoppel under 35 U.S.C. § 315(e)(1) does not apply to ongoing ex parte reexamination proceedings and that the Board may retain jurisdiction over a patent even after its expiration. In re Gesture Tech. Partners, LLC, Case No. 25-1075 (Fed. Cir. Dec. 1, 2025) (Lourie, Bryson, Chen, JJ.)

Gesture Technology owns a patent covering methods and apparatus for rapid TV camera and computer-based sensing of objects and human input for applications such as handheld devices, automotive systems, and video games. Samsung requested ex parte reexamination, which the United States Patent & Trademark Office (USPTO) granted.

While the ex parte reexamination was pending, Unified Patents, an organization that includes Samsung as a member, filed two IPR petitions. After the Board issued a final written decisions on the IPRs, Gesture Technology petitioned to terminate the ex parte reexamination, asserting that Samsung was estopped under 35 U.S.C. §315(e)(1) from “maintain[ing] a proceeding” at the USPTO challenging the patent on grounds it could have raised in the IPRs. The USPTO denied the petition, concluding that the estoppel provision does not apply to continuing ex parte reexamination proceedings.

Gesture Technology appealed both IPR final written decisions where the Board invalidated all but two claims. In the ex parte reexamination, the examiner rejected the two remaining claims as anticipated by Liebermann, a patent directed to an electronic communication system designed for deaf individuals that enables real-time interaction using sign language and speech translation. The Board affirmed. Gesture Technology appealed.

Gesture Technology argued that:

Estoppel under 35 U.S.C. §315(e)(1) should bar the reexamination because Samsung had previously participated in an IPR.
The Board had no jurisdiction because the patent expired.
The Board erred in finding anticipation based on Liebermann.

The Federal Circuit rejected Gesture Technology’s estoppel argument, explaining that § 315(e)(1) applies to an IPR “petitioner” maintaining a proceeding before the USPTO. In contrast, under 35 U.S.C. § 305, the USPTO – not the requester – maintains an ex parte reexamination. Thus, estoppel does not bar ongoing ex parte reexamination proceedings.

Gesture Technology argued that Liebermann did not correlate information with a function of the apparatus because its sending function was always selected. The Federal Circuit disagreed, finding substantial evidence that Liebermann disclosed a transmitter/receiver device with a camera performing initial image processing and transmitting processed data. Liebermann’s description of reducing images to pertinent data and sending that data to a processing center supported the conclusion that its device correlated image information with a transmission function, satisfying the claim limitations.

Finally, the Federal Circuit concluded that the Board retains jurisdiction over ex parte reexaminations even after patent expiration. Patent owners maintain rights such as the ability to sue for past damages, creating a live case or controversy that an ex parte reexamination can resolve.

Practice note: Ex parte reexamination remains a viable tool for challengers even after an IPR concludes because estoppel [...]

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From ‘best’ to bust: Multiple methods to determine “optimal/best” render claims indefinite

by Lauren Hong | Dec 4, 2025 | Patents

The US Court of Appeals for the Federal Circuit affirmed a district court’s judgment of invalidity and grant of summary judgment of noninfringement, concluding that even if excluded portions of expert testimony were considered, the judgments would remain proper. Akamai Technologies, Inc. v. MediaPointe, Inc., AMHC, Inc., Case No. 24-1571 (Fed. Cir. Nov. 25, 2025) (Taranto, Stoll, Cunningham, JJ.)

AMHC owns two patents that address systems and methods for efficiently routing streamed media content over the internet using an “intelligent distribution network” that centrally manages requests for streamed media from geographically dispersed users to mitigate bandwidth problems inherent in transmitting large volumes of data. Akamai sued AMHC and its subsidiary MediaPointe (collectively, MediaPointe) seeking a declaratory judgment of noninfringement for both patents. MediaPointe counterclaimed for infringement of both patents, after which Akamai counterclaimed for declaratory judgment of invalidity of all claims of both patents.

At the claim construction stage, the district court determined that claim limitations using “optimal/best” language were invalid for indefiniteness because the specification failed to provide a procedure or boundaries to determine what is “optimal/best.” For the remaining asserted claims, the district court granted summary judgment of noninfringement. In doing so, the district court:

Excluded as untimely presented key portions of MediaPointe’s technical expert’s testimony, without which MediaPointe could not reasonably establish infringement
Ruled that even if the testimony was considered, the record entitled Akamai to summary judgment of noninfringement.

MediaPointe appealed.

MediaPointe contended that the claims using “optimal/best” language were not indefinite, arguing that the requirement to use measurable performance data (specifically “trace-route results”) provided an objective standard. The Federal Circuit disagreed, finding that this requirement did not supply a reasonably clear and exclusive definition of “optimal/best.” The Court explained that the “trace-route results” requirement was not sufficiently clear because multiple methods could be used to determine compliance, and the patent offered no guidance on which measures to apply.

MediaPointe also challenged the summary judgment of noninfringement for the remaining claims, arguing that the district court applied an improperly narrow construction instead of the ordinary meaning of the disputed limitation. The Federal Circuit rejected this argument, finding that a skilled artisan would not have reasonably understood the claim language more broadly and that the district court’s construction was correct in light of the patent’s context. The Court concluded that because there was no evidence that Akamai’s system met this narrower limitation, even considering the excluded expert testimony, there was no triable issue of fact and no reasonable jury could find infringement.

The Federal Circuit therefore affirmed the district court’s judgment.

No escape from fees and sanctions for reckless litigation conduct

by Hannah Hurley | Dec 4, 2025 | Patents

The US Court of Appeals for the Federal Circuit affirmed attorneys’ fees awards against EscapeX IP, LLC, finding the case “exceptional” under 35 U.S.C. § 285, and upheld sanctions under 28 U.S.C. § 1927 based on counsel’s reckless litigation conduct. EscapeX IP, LLC v. Google LLC, Case No. 24-1201 (Fed. Cir. Nov. 25, 2025) (Taranto, Stoll, Stark, JJ.)

EscapeX brought suit against Google in the Western District of Texas, alleging that Google’s YouTube Music product infringed its patent directed to systems for generating artist-specified dynamic albums. After Google pointed out that the accused features were absent from YouTube Music and later demonstrated that the accused “Auto-Add” feature predated the patent’s priority date, EscapeX amended its complaint to list the correct product and refused to dismiss the case.

Shortly after EscapeX sued Google, its patent was invalidated under § 101 in a separate litigation. EscapeX did not appeal that ruling, and Google requested that EscapeX dismiss the case. In response, EscapeX filed what it characterized as a “joint stipulation of dismissal,” which Google contested because it had not agreed to such a filing. Google moved for attorneys’ fees under § 285, arguing that EscapeX had filed frivolous claims and unreasonably prolonged the litigation. The district court agreed, awarding Google its fees.

EscapeX then filed a Rule 59(e) motion to amend the judgment, attaching declarations from its CEO and an engineer to show pre-suit diligence. The district court denied the motion, finding that the evidence was not “newly discovered” and the motion was frivolous. Google successfully sought additional fees and sanctions under § 1927, resulting in an additional $63,525 jointly and severally against EscapeX and its attorneys. EscapeX appealed.

The Federal Circuit affirmed the district court decisions and found no abuse of discretion. The Court concluded that the record supported the finding that EscapeX had not conducted any pre-suit investigation and that the case was “frivolous from the start.” This conclusion was also supported by Google’s early, detailed warnings against filing the suit and EscapeX’s general nonresponsiveness.

Regarding the Rule 59(e) motion, the Federal Circuit agreed that the declarations were not “newly discovered evidence” because they were always within EscapeX’s control and knowledge. The Court rejected arguments of “manifest injustice,” which were not raised in district court and had no merit.

Finally, the Federal Circuit affirmed the sanctions under § 1927, finding that EscapeX’s counsel acted recklessly by filing a frivolous motion that multiplied proceedings. The Court noted that zealous advocacy does not excuse filing baseless motions. The Court upheld Google’s fees and sanctions in their entirety, with costs related to the appeal also awarded to Google.

Well, well, well: Indefinite claims turn out to be a typo

by Dexter Hamilton | Nov 20, 2025 | Patents

The US Court of Appeals for the Federal Circuit reversed a district court ruling that invalidated patent claims for indefiniteness, finding that the disputed language was a minor clerical error. Canatex Completion Solutions, Inc. v. Wellmatics, LLC, et al., Case No. 24-1466 (Fed. Cir. Nov. 12, 2025) (Moore, Prost, Taranto, JJ.)

Canatex sued Wellmatics and several GR Energy entities for infringing its patent directed to a releasable connection for a downhole tool string. The patent covers a two-part device used in oil and gas wells that allows operators to disconnect and retrieve the upper part of the tool string while leaving the lower part in the well if it becomes stuck.

The patent’s claims, abstract, and specification include the phrase “the connection profile of the second part.” During claim construction, the defendants argued that the phrase lacked an antecedent basis, rendering the claims indefinite. Canatex responded that the phrase should have read “the connection profile of the first part” and that a skilled artisan would immediately recognize the error. Canatex asked the district court to construe the phrase accordingly.

The district court disagreed, finding that the “pervasiveness of the error” in both the claims and the specification suggested that the error “was an intentional drafting choice and not an error at all.” The district court added that Canatex’s failure to seek correction from the United States Patent and Trademark Office suggested that the error was neither minor nor evident on the face of the patent. The district court found all asserted claims invalid for indefiniteness. Canatex appealed.

The Federal Circuit reversed. The Court found the error obvious and determined that a skilled artisan would recognize only one reasonable correction, which was changing “second” to “first.” The Court characterized the mistake as a minor clerical or typographical error and rejected arguments that alternative interpretations were plausible. The Court emphasized that its conclusion was consistent with the intrinsic evidence.

Complete inventive entity required to avoid “by another” prior art under pre-AIA § 102(e)

by Kyle Sorenson, PhD | Nov 13, 2025 | Patents

The US Court of Appeals for the Federal Circuit affirmed the Patent Trial & Appeal Board’s decision finding claims directed to cladribine regimens for treating multiple sclerosis unpatentable as obvious. The Court clarified that a disclosure can only be excluded as prior art under pre-AIA § 102(e) if it reflects the collective work of the same inventive entity as the challenged patent. Merck Serono S.A. v. Hopewell Pharma Ventures, Inc., Case No. 25-1210 (Fed. Cir. Oct. 30, 2025) (Hughes, Linn, Cunningham, JJ.)

Merck holds patents covering methods for treating multiple sclerosis using specific oral cladribine dosing regimens. Hopewell Pharma filed inter partes review (IPR) petitions challenging these patents, asserting that the claims were obvious in light of two prior art references disclosing similar cladribine dosing schedules.

Merck argued that one reference, Bodor, was not prior art because one of the named inventors on the challenged patents, De Luca, allegedly contributed to the six-line dosing disclosure in Bodor. The Board rejected this argument, finding that Merck failed to provide corroborated evidence of De Luca’s inventive contribution and concluding that the Bodor disclosure was “by another.” The Board ultimately found all claims unpatentable as obvious over the two prior art references. Merck appealed.

On appeal, Merck contended that the Board erred by applying a “bright-line rule” requiring complete identity of inventive entities to exclude a reference as not “by another.” The Federal Circuit disagreed, reaffirming the long-standing principle from In re Land (CCPA 1966): Any difference in inventive entity, whether by adding or omitting inventors, renders the prior disclosure “by another” under pre-AIA § 102(e).

The Federal Circuit explained that when a patent results from collaboration among joint inventors, a reference can be excluded only if the relied-upon portions of the reference represent the collective efforts of the same inventive team named as inventors in the patent. While evidence from fewer than all inventors may suffice, it must demonstrate that the disclosure embodies their joint contribution. Thus, even partial overlap of inventors does not prevent the earlier disclosure from being prior art.

Merck also argued that the Board’s interpretation conflicted with language in the Manual of Patent Examining Procedure (MPEP), which suggests that the work of “at least one joint inventor” could avoid prior art treatment. The Federal Circuit rejected this claim, noting that the MPEP cites Land and defines “by another” as “a different inventive entity.” Because this rule has been long established, the Court concluded that Merck had sufficient notice and was not deprived of a fair opportunity to respond.

Finally, Merck asserted that the Board failed to apply the “rule of reason” when assessing whether De Luca contributed to Bodor. The Federal Circuit disagreed, finding that the Board properly considered all evidence, including declarations, meeting minutes, and testimony, and reasonably concluded that De Luca’s alleged role was not corroborated or significant enough to make him a co-inventor.

Practice note: This decision reinforces that under the pre-AIA statute, the phrase “by another” requires complete identity of the inventive entity to [...]

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Stocks, recusal, and copycats: ‘No problem’ on APJ conflict

by Courtney Seams | Nov 6, 2025 | Patents

The US Court of Appeals for the Federal Circuit found that an administrative patent judge’s (APJ) recusal in an inter partes review (IPR) based on ownership of stock in one of the defendant’s corporations in an amount below the statutory monetary threshold was not erroneous but remanded the case for further consideration of the copying evidence. Centripetal Networks, LLC v. Palo Alto Networks, Inc., Case No. 23-2027 (Fed. Cir. Oct. 22, 2025) (Moore, Hughes, Cunningham, JJ.)

Palo Alto Networks petitioned for IPR of Centripetal’s patent. The assigned three-member Patent Trial & Appeal Board panel instituted an IPR proceeding on the petition. Cisco sought joinder to the then-pending petition. Centripetal requested rehearing of the institution decision by either the Precedential Opinion Panel or the Board panel. The Precedential Opinion Panel denied the request.

In September 2022, Centripetal learned that a member of the Board panel owned stock in Cisco. However, Centripetal did not move for recusal until December 30, 2022, when it sought recusal of the entire panel and vacatur of the institution decision.

In January 2023, the Board panel denied Centripetal’s rehearing request and granted Cisco’s joinder motion. Nevertheless, two of the three members of the panel withdrew to narrow the issues before the Board. The reconstituted panel then denied Centripetal’s motion for vacatur and held that the recusal motion was untimely, because Centripetal had been aware of the potential conflict since September 2022.

In May 2023, the Board found certain claims of Centripetal’s patent to be unpatentable as obvious. Centripetal appealed to the Federal Circuit, arguing that the Board’s decision should be vacated because the allegedly conflicted APJ recused himself only after institution and because the Board failed to address Centripetal’s copying arguments.

The Federal Circuit determined that it had jurisdiction to hear the appeal, noting that the case turned on the interpretation of ethics rules and was not the first instance in which the Court reviewed a conflict-of-interest challenge involving an institution decision. The Court concluded that the Board did not abuse its discretion in determining that Centripetal’s recusal motion was untimely, as Centripetal had been aware of the potential conflict for three months before its filing.

The Federal Circuit also addressed the substance of the recusal motion and explained that the APJ’s stock holding in Cisco was less than the statutory $15,000 threshold at all times. Although Centripetal argued that different statutory provisions applied to APJs, the Court concluded that those provisions did not govern a federal employee’s personal financial holdings. Under the applicable statute, which requires recusal only when an employee owns more than $15,000 in a party, the Court found that the APJ was not required to recuse himself.

The Federal Circuit further found that Centripetal’s due process rights were not violated. The Court explained that ethics rules for Article III judges do not apply to administrative proceedings before APJs. The Court further noted that a recent (USPTO) memorandum directing the Board to avoid empaneling judges with any stock ownership in a party was not [...]

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Reframing the claim: Plain and ordinary meaning falls to lexicography

by Lauren Hong | Nov 6, 2025 | Patents

The US Court of Appeals for the Federal Circuit affirmed a district court’s construction of a claim, finding that the plain and ordinary meaning of a disputed term was redefined by the patentee under principles of lexicography and use of intrinsic claim construction evidence. Aortic Innovations LLC v. Edwards Lifesciences Corp., et al., Case No. 24-1145 (Fed. Cir. Oct. 27, 2025) (Prost, Reyna, Chen, JJ.)

Aortic sued Edwards Lifesciences for infringing its patents directed toward a transcatheter valve with a frame component. During claim construction, the district court determined that Aortic had acted as its own lexicographer and redefined the term “outer frame” to be “a self-expanding frame,” based on the interchangeable use of the terms “outer frame,” “self-expanding frame,” and “self-expanding outer frame” when referring to the same structure in two embodiments. Based on this construction, the parties stipulated to noninfringement of the asserted patents since Edwards’ accused valve did not have a self-expanding frame. Aortic appealed the judgment of noninfringement, challenging the district court’s construction of the claim term “outer frame.” Aortic appealed.

Aortic contended that “outer frame” should be given its plain and ordinary meaning of “positioned outside” and argued that the specification did not support limiting “outer” to require “self-expanding.” The Federal Circuit disagreed, relying on both lexicographical and specification-based grounds for its construction.

In applying principles of lexicography, the Federal Circuit reasoned that if a person of ordinary skill in the art (POSITA) would understand that two claim terms were used consistently and interchangeably throughout a patent specification, those terms may be considered definitionally equivalent. Referring to several examples, the Court observed that Aortic used “outer frame,” “self-expanding frame,” and “self-expanding outer frame” interchangeably throughout the specification when describing the frame, and concluded that “outer frame” was properly construed to require “self-expanding.”

With regard to using the specification as intrinsic claim construction evidence, the Federal Circuit reasoned that the specification consistently described the “outer frame” as a “self-expanding frame” and did not restrict that feature to a particular embodiment. From this, the Court concluded that the absence of any express exception or explanation would lead a POSITA to understand that the valve’s construction required a self-expanding outer frame in all embodiments.

Aortic alternatively argued that Edwards should be judicially estopped from arguing for a construction of “outer frame” that departed from its plain and ordinary meaning. Aortic asserted that Edwards had previously argued before the Patent Trial & Appeal Board that “outer frame” should be defined using its plain and ordinary meaning, but later adopted a contrary position in front of the district court, contending that the term referred only to a “self-expanding frame.” The Federal Circuit disagreed and explained that Aortic failed to sufficiently develop its judicial estoppel argument before the district court. Absent any exceptional circumstances, the Court concluded that Aortic had forfeited the argument.

Finding Aortic’s arguments unpersuasive, the Federal Circuit affirmed the district court’s judgment of noninfringement as to the asserted patents, upholding the district court’s construction of the disputed claim [...]

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Boss move: Disclaimer that doesn’t work can still work as a disclaimer

by Joshua Revilla | Oct 30, 2025 | Patents

The US Court of Appeals for the Federal Circuit affirmed a district court’s judgment of noninfringement and no invalidity for indefiniteness, concluding that the court correctly construed the claims and properly determined that the patents’ specifications and prosecution histories would enable a person of ordinary skill in the art (POSA) to ascertain the scope of the claims with reasonable certainty. Barrette Outdoor Living, Inc. v. Fortress Iron, LP, Fortress Fence Products LLC, Case Nos. 24-1231; -1359 (Fed. Cir. Oct. 17, 2025) (Moore, Linn, Cunningham, JJ.)

Barrette sued Fortress for infringing its patents directed to a fencing assembly featuring pivoting, sliding connectors that connect pickets to rails. During claim construction, the district court determined that the terms “boss,” “projection,” and “nub” should be given the same meaning and that these “boss” terms described fastener-less and integral structures, distinguishing them from prior art. The district court also held that the terms “sliding” and “causes” were not indefinite because a POSA would understand their scope.

Following the Markman hearing, Barrette stipulated that it could not prove infringement under the court’s construction of the “boss” terms because the accused products used non-integral fasteners. Fortress stipulated, under the same construction, that it could not establish invalidity for indefiniteness. Barrette appealed, and Fortress cross-appealed.

Barrette first argued that the district court erred in finding that the specification disclaimed bosses with fasteners by disparaging prior art assemblies that used them. According to Barrette, the specification did not criticize the use of fasteners but merely distinguished the prior art designs. Fortress, however, argued that the specification repeatedly criticized assemblies employing fasteners, describing prior art systems that used fasteners to join the rails as time consuming to install. In contrast, the patented invention attributes its quick installation advantage to the use of fastener-less, integral bosses.

The Federal Circuit agreed with Barrette that the specification did not clearly and unmistakably disclaim bosses that use fasteners. The Court explained that while a patent may describe multiple advantages over the prior art, not every embodiment must incorporate each of those advantages. Accordingly, claims should not be construed to require every advancement disclosed in the specification. The Court further rejected Fortress’ argument that the claimed “boss” must always achieve the benefit of quick installation. Although the asserted patents describe ease of installation as an advantage of using bosses, that benefit does not limit the term’s structural scope. A “boss,” the Court held, is not restricted to fastener-less configurations. Accordingly, the Federal Circuit determined that the district court erred in limiting the claims to fastener-less bosses.

Barrette next argued that the district court erred by concluding that the prosecution history disclaimed non-integral bosses. The Federal Circuit rejected this argument and agreed with the district court that Barrette had clearly disclaimed non-integral boss structures during prosecution. The Federal Circuit stated that Barrette clearly distinguished prior art from the “claimed integral boss” in prosecution and expressly clarified the scope of its claims.

Barrette argued that its subsequent communications with the patent office rendered any purported disclaimer [...]

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Enablement: Skilled artisan’s knowledge no substitute for adequate written description

by Jolie B. Schenerman | Oct 30, 2025 | Patents

The US Court of Appeals for the Federal Circuit affirmed the US International Trade Commission’s (Commission) decision that a water filtration patent was invalid for lack of written description and enablement because the scope of the asserted claim was not enabled by the patent’s specification. Brita LP v. International Trade Commission, Case No. 24-1098 (Fed. Cir. Oct. 15, 2025) (Prost, Reyna, Chen, JJ.)

Brita filed a complaint at the Commission alleging that Vestergaard Frandsen and Helen of Troy infringed its water filtering patent. The main dispute focused on the patent’s only independent claim, which in part recites a “gravity-fed water filter, comprising filter media including at least activated carbon and a lead scavenger” that achieves a “Filter Rate and Performance (FRAP) factor of about 350 or less.” The patent identifies several types of filter media, including carbon filters.

The administrative law judge (ALJ) construed the term “filter usage lifetime claimed by a manufacturer or seller of the filter” to mean “the total number of gallons of water that a manufacturer or seller has validated can be filtered before the filter is replaced.” Based on this construction, the ALJ issued an initial determination finding that the asserted claims met the written description and enablement requirements.

Brita sought review of the initial determination before the full Commission. On review, the Commission reversed the ALJ’s finding of a violation, concluding that the “filter usage” term was indefinite, the asserted claims lacked adequate written description, and the claims were not enabled with respect to non-carbon block filters. Brita appealed.

To satisfy the written description requirement, a patent must demonstrate that the inventor was in possession of the claimed invention at the time of filing. This means the specification must adequately support each claim. In this case, the Federal Circuit found that the specification only supported carbon block filters meeting the claimed FRAP factor, not the broader category of “filter media” as claimed. As a result, the Court found that the asserted claims failed the written description requirement.

The Federal Circuit emphasized that the patent specification failed to support the broad claim language because of its narrow focus on carbon block filters. Specifically, the specification:

Described only carbon blocks, with other filter media mentioned solely as tested examples for FRAP factor
Provided specific formulations for carbon blocks only
Illustrated only carbon block filters in the figures
Made clear distinctions between carbon blocks and other filter types.

The Federal Circuit found persuasive the inventor’s testimony that only carbon block filters were created to meet the FRAP factor.

The Federal Circuit also affirmed the Commission’s finding that the claims were invalid for lack of enablement. Under the Federal Circuit’s 1988 In re Wands decision, enablement requires that a person of ordinary skill in the art be able to make and use the invention without undue experimentation. The Court found no reversible error in the Commission’s conclusion that undue experimentation would be required for filters other than carbon blocks to meet the claimed FRAP factor. The [...]

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