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What we have here is a failure to communicate: Expert must map all claim limitations to the accused infringement

by Benjamin Ediger, Ph.D. | Oct 2, 2025 | Patents

The US Court of Appeals for the Federal Circuit reversed jury verdicts of infringement, finding that they were not supported by substantial evidence because of deficiencies in the patent owner’s expert testimony. Finesse Wireless LLC v. AT&T Mobility LLC, Case No. 2025 WL 2713518 (Fed. Cir. Sept. 24, 2025) (Moore, C.J.; Linn, Cunningham, JJ.)

AT&T Mobility was accused of infringing two patents owned by Finesse Wireless, both directed to methods for mitigating intermodulation product interference in radios. The accused technology involved Nokia radios implementing passive intermodulation (PIM) cancellation. Nokia intervened in the case. A jury found all asserted claims valid and infringed, awarding Finesse more than $166 million in lump sum damages. AT&T and Nokia moved for judgment as a matter of law (JMOL) on both noninfringement and the damages award, and alternatively sought a new trial. The district court denied the motions. AT&T and Nokia appealed.

The Federal Circuit reversed the district court’s denial of JMOL on noninfringement and vacated the damages award, concluding that the jury verdicts were not supported by substantial evidence. The Court’s decision turned largely on shortcomings in the testimony of Finesse’s infringement expert, whose analysis was the sole basis for Finesse’s infringement case.

For the first patent, the Federal Circuit found that Finesse’s expert failed to demonstrate that Nokia’s PIM cancellation feature received all input signals required by the asserted claims. The expert relied on a Nokia diagram but misinterpreted it by mistakenly identifying a signal generated by the radio as one of the required input signals. Although the expert was made aware of the error, he did not clearly correct his position or identify alternative signals that satisfied the claim limitation. Finesse argued that the expert had corrected a “misimpression,” but the Court disagreed, finding that the expert failed to provide a clear and consistent explanation reconciling his contradictory positions.

The asserted claims of the second patent required seven multiplications involving three signals. Finesse’s expert relied solely on a Nokia document that listed only three multiplications yet equated them to the seven required by the claims. The Federal Circuit found this testimony inadequate, noting that the expert failed to explain how the three multiplications mapped to the seven required. On appeal, Finesse argued that the document actually evidenced 10 multiplications, but the Court was unpersuaded. Neither Finesse nor its expert explained how the 10 multiplications corresponded to the seven required multiplications, nor did they reconcile this new position with the expert’s prior reliance on only three multiplications.

Because Finesse failed to present expert testimony that adequately mapped each claim limitation to the accused method, the Federal Circuit reversed the jury’s infringement findings for both patents and vacated the damages award.

Practice note: The decision underscores the importance of detailed and consistent expert analysis in patent infringement cases, particularly when expert testimony is the sole basis for proving infringement.

Functional relationship recitation can’t overcome anticipating prior art

by Tim Dunker | Oct 2, 2025 | Patents

Underscoring functional relationships as limitations in patent claims and the importance of claim construction, the US Court of Appeals for the Federal Circuit affirmed in part, vacated in part, and remanded a Patent Trial & Appeal Board decision that found claims of a patent unpatentable notwithstanding a functional relationship recitation. Bayer Pharma Aktiengesellschaft v. Mylan Pharmaceuticals Inc., et al., Case No. 23-2434 (Fed. Cir. Sept. 23, 2025) (Moore, Cunningham, Scarsi, JJ.)

Bayer owns a patent that describes the results of a phase III clinical trial that evaluated the efficacy and safety of administering rivaroxaban with and without aspirin for the prevention of major adverse cardiac events. Certain claims require “administering to the human patient rivaroxaban and aspirin in amounts that are clinically proven effective in reducing the risk of myocardial infarction, stroke or cardiovascular death[,] wherein rivaroxaban is administered in an amount of 2.5 mg twice daily and aspirin is administered in an amount of 75 – 100 mg daily.” Other claims are directed to a once daily administration of “a first product comprising rivaroxaban and aspirin” and “a second product comprising rivaroxaban.”

Mylan challenged the patent in inter partes review (IPR), arguing that certain claims were anticipated by the Foley reference and others were obvious over Foley alone or in combination with Plosker. The Board agreed, finding all challenged claims unpatentable. Bayer appealed.

Bayer argued that the Board erred in:

Construing “clinically proven effective” as non-limiting and finding, in the alternative, that it was inherently anticipated
Construing “first product comprising rivaroxaban and aspirin” to encompass administration of rivaroxaban and aspirin as separate dosage forms
Failing to articulate why a skilled artisan would have combined Foley and Plosker with a reasonable expectation of success
Failing to analyze whether clinical proof of efficacy was an unexpected result

The Federal Circuit declined to resolve whether “clinically proven effective” is a limiting claim element, concluding that even if it were, it would not render the claims patentable. The Court explained that the phrase does not create a “new and unobvious functional relationship” with the known method of treatment. Analogizing to a hypothetical claim for a known drug method modified by a post-dated accolade (e.g., “Best Drug of 2026”), the Court emphasized that requiring clinical proof of efficacy does not transform the underlying treatment process.

Bayer relied on the Federal Circuit’s 2019 decision in Allergan Sales v. Sandoz, in which the Court found “wherein” clauses specifying safety and efficacy to be material to patentability. The Federal Circuit distinguished Allergan, noting that the claims there were written in open format and the “wherein” clauses modified the overall composition. In contrast, the claims of Bayer’s patent already specified exact dosages, and “clinically proven effective” did not modify any particular component. The Court therefore affirmed the Board’s finding of unpatentability for these claims.

However, the Federal Circuit agreed with Bayer on the construction of claims requiring a “first product comprising rivaroxaban and aspirin.” Bayer argued that this language required a single dosage [...]

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The smoke has cleared – and so has your invalidity defense

by Jodi Benassi | Sep 25, 2025 | America Invents Act, Patents

The US District Court for the Northern District of Iowa issued an instructive decision clarifying the scope of statutory estoppel under the Leahy-Smith America Invents Act (AIA) following post-grant review (PGR) proceedings before the Patent Trial & Appeal Board. Intirion Corp. v. College Products, Inc., Case No. 23-cv-4023-CJW-KEM (N.D. Iowa Sept. 16, 2025) (Williams, J.)

Intirion brought a patent infringement suit against College Products, which responded by petitioning the Board for PGR, challenging the patents based on obviousness and indefiniteness. While the PGR was pending, the district court proceeded with claim construction and initially found the terms “level of smoke,” “amount of smoke,” and “dangerous condition” indefinite. Intirion moved for reconsideration, and College Products filed a motion for partial summary judgment asserting invalidity. Intirion also sought a stay of the litigation pending the PGR outcome, which the court granted.

The Board instituted review of all claims. Initially, it found that neither party had requested express construction of any terms and adopted Intirion’s interpretation that “level of smoke” and “amount of smoke” meant “merely detecting smoke,” based on Intirion’s representations in the district court. In its final written decision (FWD), the Board acknowledged the district court’s indefiniteness findings but ultimately adopted the plain and ordinary meaning of the terms, concluding that a person of ordinary skill in the art could determine appropriate thresholds using known methods. Expert testimony persuaded the Board that defining the terms by their function was sufficiently definite under patent law.

After the Board upheld the claims, the district court found that College Products was estopped under 35 U.S.C. §325(e)(2) from asserting any invalidity grounds (including indefiniteness and obviousness) that were or reasonably could have been raised during the PGR. The district court explained that the AIA established a streamlined system allowing third parties to challenge the patentability of issued claims before the Board as a quicker and more cost-effective alternative to litigation. This structure is specifically designed to prevent challengers from getting multiple bites at the apple by raising the same or similar arguments in subsequent court proceedings.

College Products argued that estoppel should not apply because it filed its motion for partial summary judgment before the Board issued its FWD. The district court rejected this argument, explaining that the statutory language provides no exception based on timing and imposes a clear bar once the Board has issued a FWD. The district court also found that College Products’ position was inconsistent with applicable case law and noted that it failed to cite any contrary authority.

The district court further explained that it had intentionally deferred ruling on College Products’ motion for partial summary judgment of invalidity pending the outcome of the PGR proceedings. Once the PTAB issued its FWDs, College Products was estopped from further challenging the validity of the patents, including through its pending summary judgment motion, because it could have raised any such indefiniteness arguments during the PGR process.

Practice note: Unlike inter partes review (IPR), during PGR a petitioner can challenge patentability on grounds [...]

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Surprise? Last-minute new theory leads to new trial

by Dexter Hamilton | Sep 18, 2025 | Patents

The US Court of Appeals for the Federal Circuit reversed a district court’s denial of a new trial after the defendant introduced a new noninfringement theory on the eve of trial based on test results it previously refused to produce, saying they were not necessary. Magēmā Technology LLC v. Phillips 66, Phillips 66 Co., and WRB Refining LP, Case No. 2024-1342 (Fed. Cir. Sept. 8, 2025) (Moore, Stoll, Bumb, JJ.)

Magēmā owns a patent directed to a solution to desulfurize fuel used to power cargo ships. Magēmā entered into licensing discussions with Phillips, but after the parties failed to reach an agreement, Phillips modified its hydrotreater reactors to implement what Magēmā believed was an infringing desulfurization process. Magēmā sued.

The governing fuel standard required a flashpoint of at least 140 degrees, meaning fuel with a pre-hydroprocessing flashpoint below that threshold would not infringe. The parties disagreed on where at the refinery the flashpoint should be tested. Phillips provided data from one sampling point while Magēmā requested data from a location closer to the hydrotreater reactor. Phillips refused, citing safety concerns, and argued that Magēmā could estimate the flashpoint using an accepted formula. The district court denied Magēmā’s motion to compel, agreeing that the formula sufficed. However, after discovery closed, Phillips moved to supplement the summary judgment record with new flashpoint test results from a different sampling station. The district court denied the motion, finding Phillips had no reasonable explanation for failing to sample earlier, and that introducing the evidence late would be unduly prejudicial, especially since Phillips had previously said Magēmā could rely on the formula. Yet shortly before jury selection, Magēmā learned that Phillips intended to argue that the formula was inadequate and that only actual testing could prove infringement (evidence Magēmā lacked), effectively shifting the burden. Magēmā objected, but the district court overruled the objection.

At trial, Philips told the jury that the standard required actual flashpoint testing and that Magēmā could not prove infringement without test samples. Magēmā requested a curative instruction, which the district court denied. The district court also barred Magēmā from explaining why it had relied on a formula rather than actual testing data. The jury returned a general verdict of noninfringement. Although the district court acknowledged that Phillips’ arguments were “improper and prejudicial,” it denied Magēmā’s motion for a new trial, finding that the misconduct did not affect the outcome. Magēmā appealed.

Phillips argued that Magēmā had failed to timely object, but the Federal Circuit disagreed, citing to Magēmā’s pre-jury selection objection, request for a curative instruction, and motion for a new trial. Finding that the district court abused its discretion in denying a new trial, the Federal Circuit agreed that Phillips’ argument was “improper and prejudicial,” characterizing it as a “bait-and-switch.”

Because the jury returned a general verdict form, the Federal Circuit could not determine the basis for the noninfringement finding and, given the repeated emphasis Phillips placed on its improper argument, the Court concluded it would be unjust to let the [...]

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Prevailing party: Dismissal with prejudice will do it

by Kyle Sorenson, PhD | Sep 18, 2025 | Patents

The US Court of Appeals for the Federal Circuit found that a district court erred in denying fees and costs to the prevailing party (here, the defendant), but upheld the district court’s denial of Rule 11 sanctions. Future Link Sys., LLC v. Realtek Semiconductor Corp., Case Nos. 23-1056; -1057 (Fed. Cir. Sept. 9, 2025) (Stoll, Reyna, Bryson, JJ.)

Future Link sued Realtek for patent infringement in the Western District of Texas. Realtek challenged service and personal jurisdiction and subsequently moved for Rule 11 sanctions. During discovery, Future Link produced a licensing agreement with a third party, under which the third party had agreed to pay a lump sum if Future Link sued Realtek. Shortly afterward, Future Link entered into a separate licensing agreement with Realtek covering the accused products and voluntarily dismissed the case.

Realtek moved for attorneys’ fees under 35 U.S.C. § 285 and costs under Rule 54(d)(1), and asserted that Future Link had filed objectively baseless lawsuits. The district court denied Realtek’s motions for fees and sanctions, did not address the motion for costs, and converted Future Link’s voluntary dismissal to a dismissal with prejudice.

Fees and costs

To seek fees and costs, a party must qualify as “the prevailing party.” In reviewing the district court’s decision on fees and costs, the Federal Circuit addressed Realtek’s prevailing party status under both § 285 and Rule 54(d).

Applying de novo review, the Federal Circuit concluded that Realtek was the prevailing party, despite the voluntary dismissal, because the district court had converted that dismissal to one with prejudice. The Federal Circuit emphasized that prevailing party analysis turns on whether there has been a material alteration of the legal relationship between the parties. Citing its own precedent, the Court explained that a dismissal with prejudice constitutes such a change because it bars the plaintiff from reasserting the same claims against the same products.
The Court explained that a favorable ruling on the merits is not required. A defendant that successfully avoids liability, such as through dismissal with prejudice, can still be deemed the prevailing party.

Since the dismissal with prejudice prevented Future Link from reasserting its patent claims against the accused products, Realtek was the prevailing party. The Federal Circuit vacated the district court’s denial of attorneys’ fees under § 285 and remanded the issue for consideration of whether the case was exceptional and fees were warranted. It likewise remanded the Rule 54(d) costs issue for initial determination.

Rule 11 sanctions

The Federal Circuit affirmed the district court’s denial of Rule 11 sanctions. Realtek had argued that Future Link’s prefiling investigation was inadequate and that the lawsuit was improperly motivated by a third-party payment arrangement, making that arrangement the but-for cause of the lawsuit.

The Federal Circuit rejected both arguments. First, it found that Future Link’s pre-suit investigation met Rule 11 standards: Future Link obtained and analyzed three accused products, prepared claim charts comparing asserted patent claims to the accused products, and investigated relevant optional features that it reasonably believed [...]

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Claims barred by laches: Prosecution delay doesn’t pay, nor does skipping evidence of concrete injury

by Courtney Seams | Sep 11, 2025 | Patents

The US Court of Appeals for the Federal Circuit affirmed a district court’s judgment for the US Patent & Trademark Office (PTO) on application of prosecution laches in an action under 35 USC § 145. The Federal Circuit also agreed that the district court lacked Article III jurisdiction over certain claims because the plaintiff failed to provide evidence of concrete injury when challenged after initial pleadings. Hyatt v. Stewart, Case Nos. 2018-2390; -2391; -2392; 2019-1049; -1038; -1039; -1070; 2024-1992; -1993; -1994; -1995 (Fed. Cir. Aug. 29, 2025) (Reyna, Wallach, Hughes, JJ.) (precedential).

Gilbert Hyatt filed four GATT bubble patent applications, all of which had claims rejected by the examiner. Hyatt appealed those rejections to the Patent Trial & Appeal Board, which affirmed various rejections of others. Following the Board decisions, Hyatt filed four separate actions in district court under 35 U.S.C. § 145, challenging the PTO rejections. In response, the PTO asserted prosecution laches as an affirmative defense and, in the alternative, invalidity, based on anticipation and lack of written description.

The district court initially ruled in Hyatt’s favor, finding that the PTO’s affirmative defenses failed with respect to the claims for which the Board affirmed the examiner’s rejection. The district court concluded that it lacked Article III jurisdiction over the remaining claims (those for which the Board reversed the examiner) because there was no final agency action as to those claims.

The PTO appealed, arguing that prosecution laches barred all of the claims or, in the alternative, that the claims were invalid. Hyatt cross-appealed, contending that prosecution laches did not apply in § 145 actions or that the district court abused its discretion in applying laches in these specific § 145 actions.

In an earlier appeal, Hyatt I, the Federal Circuit vacated the district court’s rulings on prosecution laches, holding that the district court applied the wrong standard for prosecution laches and had the burden of proving that Hyatt engaged in unreasonable and unexplained delay in prosecuting his applications and that the delay was prejudicial. The panel remanded the case held the issue of Article III jurisdiction in abeyance. On remand, the district court reversed course and found in favor of the PTO on prosecution laches, concluding that Hyatt had unreasonably delayed prosecution in a manner that prejudiced the agency.

Hyatt appealed. The Federal Circuit consolidated the appeals with the earlier stayed jurisdictional issues. The Federal Circuit affirmed the district court’s application of prosecution laches, finding no clear error in its determination that Hyatt’s conduct met the standard for delay and prejudice. The Federal Circuit also agreed that the district court lacked Article III jurisdiction over claims that had not been finally rejected by the PTO, reinforcing that § 145 actions may only proceed where there is a final agency determination resulting in a justiciable controversy.

On the issue of prosecution laches, the Federal Circuit explained that it had already considered and rejected Hyatt’s argument that prosecution laches is unavailable in a § 145 action in Hyatt I, and [...]

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Derivation proceedings highlight race to file under AIA

by Brennen Baylor | Sep 11, 2025 | America Invents Act, Patents

In one of the first decisions regarding derivation proceedings under the America Invents Act (AIA), the US Court of Appeals for the Federal Circuit affirmed the Patent Trial & Appeal Board’s finding that an application earlier filer had not derived his claimed invention from a later-filing petitioner. Global Health Solutions, LLC v. Marc Selner, Case No. 2023-2009 (Fed. Cir. Aug. 26, 2025) (Stoll, Stark, JJ.) (Goldberg, J., sitting by designation).

Global Health Solutions (GHS) and Marc Selner filed patent applications governed by the AIA and covering similar subject matter. Selner filed his application first. GHS filed a petition to institute derivation under 35 U.S.C. § 135, alleging that Selner’s patent claims were derived from Burnam, the single inventor on the GHS application.

During Board proceedings, the parties submitted evidence regarding the timing of their respective conceptions of the claimed inventions, including several email communications. Based on Selner’s evidence, the Board determined that he could not have derived the claimed invention from Burnam. The Board also rejected GHS’s argument that actual reduction to practice was necessary to complete conception of the claimed invention. GHS appealed.

The Federal Circuit explained that while pre-AIA patent interference proceedings required a party alleging derivation to establish prior conception and communication of the invention to the opposing party, the AIA does not expressly define the evidentiary requirements for derivation petitions. Nevertheless, the Court, borrowing from its interference jurisprudence, reasoned that an AIA derivation proceeding similarly requires a showing of both conception and communication of the claimed invention. The Court emphasized, however, that standards articulated in case law from pre-AIA interference proceedings must be applied with caution and considered in light of the AIA’s distinct statutory framework.

The Federal Circuit determined that although the Board focused on which party had proof of the earliest conception (typically the dispositive issue in interference proceedings), it was harmless error. Under the AIA first-to-file framework, determination of the first to invent is not dispositive. The Court noted that because Selner was first to file, he only needed to show that his conception was independent of Burnam’s. Here, Selner’s proof of earlier conception was also proof of conception independent of Burnam, the Court noted.

The Federal Circuit also determined that the Board did not err in rejecting GHS’s argument that Selner failed to demonstrate invention in the absence of evidence of actual reduction to practice. The Court found that the Board appropriately addressed whether such a requirement (often applied in interference proceedings to complicated, unpredictable technology) applied to the invention at issue. The Court explained that Selner’s conception was complete either when he could define the invention by its method of preparation or when he had formed a definite and permanent idea of the complete and operative invention. Selner’s earlier email communication to Burnam supported the finding that Selner had reached the requisite understanding to establish complete conception without the need for actual reduction to practice. Accordingly, the Court affirmed the Board’s decision in favor of Selner, finding no derivation.

Practice note: [...]

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Feel the burn: Mechanical improvement is patent eligible under § 101

by Dexter Hamilton | Aug 21, 2025 | Patents

The US Court of Appeals for the Federal Circuit reversed a district court’s partial dismissal of the plaintiff’s patent claims under 35 U.S.C. § 101, finding that the claims were not directed to an abstract idea under Alice step one. PowerBlock Holdings, Inc. v. iFit, Inc., Case No. 24-1177 (Fed. Cir. Aug. 11, 2025) (Taranto, Stoll, Scarsi, JJ.)

PowerBlock sued iFit for allegedly infringing its patent related to dumbbells. IFit moved to dismiss the claims under § 101. The district court found that the challenged claim was broadly directed to the idea of automated weight stacking, and that it purported to cover any system having a few basic components for selecting and adjusting weights, rather than describing a specific method or design for how the system actually worked. Applying the Supreme Court’s two-step framework for determining patent eligibility, the district court determined that all but one claim of the asserted patent were ineligible under § 101. PowerBlock appealed.

The Federal Circuit reversed, finding that the district court erred in its Alice step one analysis under § 101. The Court explained that the crux of the district court’s incorrect determination was that the challenged claim was directed to the abstract idea of automated weight stacking, which in turn led to misplaced preemption concerns. The Court found instead that the claim was limited to a specific implementation of a technological improvement – namely, a particular type of selectorized dumbbell featuring nested left and right weight plates, a handle, a movable selector, and an electric motor operatively connected to the selector that adjusts the weight based on user input.

Distinguishing the challenged claim from prior cases in which claims were found ineligible, the Federal Circuit emphasized that the claim was directed to an “eligible mechanical invention” and “focused on a specific mechanical improvement,” not merely an abstract or generalized concept. The Court also rejected iFit’s argument that limitations should be discounted simply because they appear in the prior art. The Court reiterated that it is inappropriate to dissect claims into old and new elements and then ignore the old when assessing eligibility under § 101. Rather, under Alice, the “step one inquiry involves consideration of the claims ‘in their entirety to ascertain whether their character as a whole is directed to excluded subject matter.’” The Court cautioned against conflating the patent eligibility inquiry under § 101 with the separate questions of novelty and nonobviousness under §§ 102 and 103.

Identical or not? Jury can’t decide issues of claim construction

by Cecilia Choy, PhD | Aug 21, 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) of noninfringement, finding that the jury’s infringement findings were unsupported by sufficient evidence and that the district court had improperly delegated claim construction to the jury. Laboratory Corp. of America Holdings v. Qiagen Sciences, LLC, Case No. 23-2350 (Fed. Cir. Aug. 13, 2025) (Lourie, Dyk, Cunningham, JJ.)

Laboratory Corp. of America Holdings (LabCorp) holds two patents with substantially overlapping specifications, both generally directed to methods for preparing DNA samples for sequencing and enrichment techniques aimed at enabling whole-genome sequencing. LabCorp initiated litigation alleging that various Qiagen Sciences kits containing materials used in DNA sample preparation for sequencing infringed its patents. During claim construction, the district court construed several patent terms as follows:

In the first patent, “second target-specific primer” means a single-stranded oligonucleotide with a 3’ portion that specifically anneals to a portion of the known target nucleotide sequence in the amplicon from step (b), and a 5’ portion identical to a second sequencing primer.
Also in the first patent, “second adaptor primer” refers to a nucleic acid molecule containing a sequence identical to part of the first sequencing primer and nested relative to the first adaptor primer.
In the second patent, “target-specific primer” is defined as a primer sufficiently complementary to the target to enable selective annealing and amplification, without amplifying non-target sequences in the sample.

The jury found that Qiagen infringed the first patent under the doctrine of equivalents and willfully and literally infringed the second patent. The jury awarded damages accordingly. The district court denied Qiagen’s renewed motion for JMOL to reverse the damages and the jury’s findings of infringement and validity, and its alternative request for a new trial. Qiagen appealed.

Qiagen raised two noninfringement arguments regarding the first patent, and the Federal Circuit agreed with both. First, the Court held that it was error to allow the jury to apply “plain meaning” and equate a sequence being “identical to another” with being “identical to a portion” of another. Specifically, Qiagen’s accused second target-specific primer (Sample Index Primer, or SIP) was 19 nucleotides long while the second sequencing primer (Read2 primer) was 34 nucleotides. The fact that they shared an overlapping sequence did not make them identical.

Although the district court had treated “identical” as a factual issue for the jury, the Federal Circuit, citing its 2008 decision in O2 Micro Int’l Ltd. v. Beyond Innovation Tech., found that this was a claim construction matter that should not have been left to the jury. The term “identical” must be given its full meaning under claim construction and cannot be interpreted as “identical to a portion.” The Court emphasized that the specification and claims distinguished between full and partial identity: The second target-specific primer must be “identical to” the second sequencing primer while the adaptor primer need only be “identical to a portion” of the first sequencing primer. This difference [...]

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Specification controls: Written description must be clear

by Taylor MacDonald | Aug 21, 2025 | Patents

The US Court of Appeals for the Federal Circuit reversed a district court’s decision upholding patent validity, finding that the subject patent’s specification clearly established that the written description failed to adequately support the full scope of the asserted claims (35 U.S.C. § 112). Mondis Technology Ltd. v. LG Electronics Inc., Case Nos. 23-2117; -2116 (Fed. Cir. Aug. 8, 2025) (Taranto, Clevenger, Hughes, JJ.)

Mondis sued LG for alleged infringement of a patent related to computer display technology. During prosecution, Mondis amended the claims to overcome prior art, changing a limitation from identifying a particular display unit to identifying a type of display unit (the type limitation). A jury found in favor of Mondis and awarded $45 million in damages. LG moved for judgment as a matter of law (JMOL), arguing that the patent was invalid due to a lack of written description supporting the type limitation. The district court denied the motion but granted a retrial on damages. The second jury awarded more than $14 million. LG appealed.

The Federal Circuit applied regional law standard (here, Third Circuit law) to review the district court’s denial of JMOL (i.e., assessing whether a reasonable jury could have reached the verdict). In evaluating patent validity under the written description requirement of § 112, the Court focused on whether the specification sufficiently demonstrated that the inventor possessed the claimed invention, including any amendments made during prosecution.

The Federal Circuit examined whether substantial evidence supported the jury’s finding of validity and concluded that LG did not need extrinsic evidence to challenge the patent’s validity but properly relied on the specification. The Court found that Mondis’ attempt to piece together fragments of testimony (primarily related to infringement) to argue for implicit support in the specification was insufficient because the specification’s plain language supported only the original unamended claim limitation, not the amended type limitation.

The Federal Circuit acknowledged that both parties presented expert testimony at trial. However, the Court found that even Mondis’ expert testimony, when considered alongside the specification’s plain meaning, failed to provide adequate support for the jury’s finding. While a jury may infer implicit support, Mondis did not present enough particularized testimony to justify such an inference.

Mondis also argued that the examiner’s allowance of the amended claim indicated sufficient support in the specification, and that the presumption of validity of an issued patent supported its position. The Federal Circuit rejected this argument, noting that the examiner’s focus was on overcoming prior art, not on evaluating written descriptions. Accepting Mondis’ position would effectively shield most patents from later invalidation, a result the Court deemed impractical.

Accordingly, the Federal Circuit reversed the district court’s ruling and found the asserted claims invalid for lack of written description.