ranges : CAFC Alert

Written Description Compliance Requires Lack of Different Inventions Achieved by Claimed and Disclosed Ranges

| April 19, 2024


Decided: February 9, 2024

Chen, Stoll, and Cunningham.  Opinion by Stoll.


The CAFC addressed a question of written description compliance where a numerical range set forth in a patent claim is narrower than and encompassed by a disclosed range in the specification. The CAFC found that the written description requirement is met under fact-specific circumstances where substantial evidence indicates that a skilled artisan would see no different inventions resulting from the claimed range and the disclosed range.


RAI appealed a final written decision by the Patent Trial and Appeal Board in a post-grant review (PGR) finding certain claims of RAI’s U.S. Patent No. 10,492,542 (“the ’542 patent”) unpatentable.  RAI challenged, among other issues,[1] the Board’s finding that claims 10 and 27 of the ’542 patent lack adequate written description under 35 U.S.C. § 112.

The ’542 patent relates to electrically powered “smoking articles” which, as in e-cigarettes, use an electrical heating element to heat tobacco or like substance to form an inhalable vapor or aerosol.  Claims 10 and 27—added by preliminary amendment in the underlying application which is a continuation from a former application having no such claims in the original filing—specify that the heating element has a certain range of length, which is not disclosed verbatim in the specification.

The written description requirement is a question of fact subject to substantial evidence review. The CAFC prefaced the written description analysis with the general threshold for compliance: the disclosure must “reasonably convey[ to a skilled artisan] that the inventor had possession of the claimed subject matter as of the filing date.”  The CAFC then discussed precedents finding written description support, or lack thereof, for claimed ranges that are narrower than ranges described in specifications.

Courts finding adequate written description: Wertheim, Blaser, Kolmes[2]

In Wertheim, the parameter at issue was “solids content of the concentrated coffee extract.”  The claimed range “between 35% and 60%” was found adequately supported by the specification disclosing a broader range of “25% to 60%” along with specific examples where the parameter was either “36% or 50%.”  The Wertheim court held that presence of a clear indication that “the broad described range pertains to a different invention than the narrower (and subsumed) claimed range” (emphasis added) would negate adequacy of written description, whereas absence of such indication would support written description compliance.

Two subsequent courts followed Wertheim.  InBlaser, the claimed range of temperature for heating a reaction blend for acylation, “80º to 200º C.” was found adequately supported by the disclosure of a broader range of “between 60º and 200º C.”  In Kolmes, the claimed range of wrapping rate for cut-resistant yarn, “8–12 turns per inch,” was found adequately supported by the disclosure of a broader range of “4–12 turns per inch, with 8 turns per inch being preferred.”

Courts finding no adequate written description: Baird, Indivior[3]

Baird involved a patent application which included claims copied from an issued patent for an interference proceeding, i.e., the applicant was not the original author of the copied claims. The parameter at issue was a quench bath temperature in production of stretch-orienting polypropylene. The claimed range was “from about 40[º F] to … about 60 [º F].”  While this range was explained in the issued patent as having certain criticality, the applicant’s specification disclosed a broader range of “between 32º F and 176º F,” while silent on the narrower range. Finding lack of adequate support, the Baird court reasoned that the copied claim pertained to a “different” invention from that disclosed in the specification.  

In Indivior, the parameter at issue was a concentration of certain polymers in thin film formulation.  Disputed claims recited two numerical ranges: (A) “about 40 wt % to about 60 wt %” and (B) “about 48.2 wt % to about 58.6 wt %.”  The specification disclosed broader  ranges—or lower bounds without express upper bounds—of “at least 25” and “at least 50,” as well as specific instances of “48.2” and “58.6” gleaned from data tables.  The specification also stated that the parameter may be at “any desired level.”  The claimed range (A) failed the written description requirement because the specification did not literally recite the range or the endpoints, while the “any desired level” statement obscured the scope of the invention. The claimed range (B) also failed the written description requirement because, although the endpoints were disclosed at least implicitly, it was unclear that the specification described the range bound by these endpoints.

Application to Claims 10 and 27 of the ’542 patent

After summarizing the precedents, the CAFC turned to the claims at issue.  Claims 10 and 27 both recite that a heating member used in the smoking device has “a length of about 75% to about 85% of a length of the disposable aerosol forming substance.”  The specification describes four progressively narrow, nested ranges for the parameter: “about 75% to about 125%,” “about 80% to about 120%,” “about 85% to about 115%,” and “about 90% to about 110%.”  The Board’s finding of no written description was driven by the fact that the upper endpoint “85%” of the claimed range does not have a corresponding upper endpoint in any of the disclosed ranges.

The CAFC found that the written description requirement is met.  To reach the conclusion, the CAFC centered its analysis on “different invention” test set forth in Wertheim, restating that “[t]he specification need not expressly recite the claimed range to provide written description support.”  The factual inquiry looked to specific factors, including:

  • Express disclosure in the specification: Although the claimed range itself is not literally disclosed, both of its endpoints are identified as part of the disclosed ranges. 
  • Predictability and complexity of the invention: Since the smoking device invention relates to a relatively predictable, electro-mechanical field, and the claim language is simple, the level of clarity or details required to satisfy the written description requirement is low.
  • Lack of indication that the claimed parameter affects the invention: The specification nowhere indicates that “operability, effectiveness, or any other parameter” of the invention is impacted by changing the claimed parameter.

Based thereon, the CAFC found no “different invention” arising from the claimed range than that disclosed in the specification.

            The CAFC distinguished Indivior and Baird relied upon by the Board.  Unlike Indivior, the ’542 patent discloses the endpoints and contains no inconsistent statements regarding the range (e.g., that “any desired level” may work); plus the predictability of the electro-mechanical invention is higher than the chemical invention set forth in the Indivior claims. Also, unlike Baird where the claimed range was shown to have criticality over the boarder disclosed range, no evidence was presented in the present case that the broader disclosed range operates differently than the claimed range. 

            Additionally, the CAFC dismissed an expert testimony offered by Phillip Morris pointing to different center points of the disclosed range (100%) and the claimed range (80%).  The expert evidence was not enough to overcome the intrinsic evidence and the case law supporting adequacy of the written description.  


            This case exemplifies one way in which a court may apply case-by-case analysis of written description compliance.  Where the claimed range is narrower than and subsumed in the disclosed range, the “different invention” test may not only examine the express disclosure and the nature of the technology, but also may consider whether varying the parameter inside and outside the claimed range would make any difference.

While the test could be useful in establishing written description support—given that a patent specification typically describes numerical ranges in connection with one general inventive concept—caution should be used in asserting lack of different inventions emanating from different numerical ranges; such admission might be used by an opponent to support obviousness of the claimed range.  The dilemma may be avoided, for example, by drafting an original disclosure to describe both commonalities and differences across broad and narrow ranges as well as specific values of a key parameter.

[1] RAI’s other argument challenged the Board’s obviousness finding of other claims of the ’542 patent, which was affirmed by the CAFC on appeal.

[2] In re Wertheim,541 F.2d 257 (C.C.P.A. 1976), In re Blaser, 556 F.2d 534 (C.C.P.A. 1977), and Kolmes v. World Fibers Corp., 107 F.3d 1534 (Fed. Cir. 1997).

[3] In re Baird,348 F.2d 974 (C.C.P.A. 1965), and Indivior UK Ltd. v. Dr. Reddy’s Laboratories S.A., 18 F.4th 1323 (Fed. Cir. 2021). 

A small increase in a Prior Art’s taught range needs to have sufficient reason for the modification to establish obviousness under 35 U.S.C. §103

| August 6, 2021

Chemours Co. FC, LLC vs Daikin Ind., LTD

Decided on July 22, 2021

NEWMAN, DYK, and REYNA. Opinion by Reyna. Concurring and Dissenting in part by Dyk.


Chemours Company FC, LLC, appealed the final written decisions of the  Patent  Trial  and  Appeal  Board  from  two inter partes reviews brought by Daikan Industries, Ltd.  Chemours argued on appeal that the Board erred in its obviousness factual findings and did not provide adequate support for its analysis of objective indicia of nonobviousness.  The CAFC found that the Board’s decision on obviousness  was  not  supported  by  substantial evidence and that the Board erred in its analysis of objective indicia of nonobviousness.  Consequently, they reversed the Board’s decision.  


Chemours Company FC, LLC, appealed the final written decisions of the Patent Trial and Appeal Board from two inter partes reviews brought by Daikan Industries, Ltd., et al. Chemours argues on appeal that the Board erred in its obviousness factual findings and did not provide adequate support for its analysis of objective indicia of nonobviousness. 

Two patents were at issue.  U.S.  Patent  No.  7,122,609  (the  “’609  patent) and U.S. Patent No. 8,076,4312 (the “’431 patent”). The representative ’609 patent relates to a unique polymer for insulating communication cables formed by pulling wires through melted polymer to coat and insulate the wires, a process known as “extrusion.”

Claim 1 of the ’609 patent is representative of the issues on appeal:

1. A partially-crystalline copolymer comprising tetrafluoroethylene, hexafluoropropylene in an amount corresponding to a hexafluoropropylene index (HFPl) of from about 2.8 to 5.3, said copolymer  being polymerized and isolated in the absence of  added alkali metal salt, having a melt flow rate of  within the range of about 30±3 g/10 min, and having no more than about 50 unstable end groups/106 carbon atoms.

The Board found all challenged claims of the ’609 patent and the ’431 patent to be unpatentable as obvious in view of U.S. Patent No. 6,541,588 (“Kaulbach”).

On appeal, Chemours argued that Daikin did not meet its burden of proof because it failed to show that a person of ordinary skill in the art (“POSA”) would modify Kaulbach’s polymer to achieve the claimed invention.

The Kaulbach reference teaches a polymer for wire and cable coatings that can be processed at higher speeds and at higher temperatures. Kaulbach highlights that the polymer of the invention has a “very narrow molecular weight distribution.” Kaulbach discovered that prior beliefs that polymers in high-speed extrusion application needed broad molecular weight distributions were incorrect because “a narrow molecular weight distribution performs better.” In order to achieve a narrower range, Kaulbach reduced the concentration of heavy metals such as iron, nickel and chromium in the polymer.

In the Kaulbach example relied on by the Board, Sample A11, Kaulbach’s melt flow rate is 24 g/10 min, while the claimed rate of Claim 1 of the ‘609 patent is 30±3 g/10 min.

The Board found that Kaulbach’s melt flow rate range fully encompassed the claimed range, and that a skilled artisan would have been motivated to increase the melt flow rate of Kaulbach’s preferred embodiment to within the claimed range to coat wires faster.  Specifically, the Board found:

We also are persuaded that the skilled artisan would have been motivated to increase the [melt flow rate] of Kaulbach’s Sample A11 to be within the recited range in order to achieve higher processing speeds, because the evidence of record teaches that achieving such speeds may be possible by increasing a [polymer’s] [melt flow rate].

In addition, the Board found that the portions of Kaulbach’s disclosure lacked specificity regarding what is deemed “narrow” and “broad,” and that it would have been obvious to “broaden” the molecular weight distribution of the claimed polymer.

Second, Chemours argued that the Board legally erred in its analysis of objective indicia of nonobviousness by showings of commercial success finding an insufficient nexus between the claimed invention and Chemours’s commercial polymer, as the Board required market share evidence to show commercial success.

CAFC Decision:

  1. Obviousness and teaching away

The CAFC found that the Board ignored the express disclosure in Kaulbach that teaches away from the claimed invention and relied on teachings from other references that were not concerned with the particular problems Kaulbach sought to solve. In other words, the Board did not adequately grapple with why a skilled artisan would find it obvious to increase Kaulbach’s melt flow rate to the claimed range while retaining its critical “very narrow molecular-weight distribution.”

The Court maintained that the Board’s reasoning does not explain why a POSA would be motivated to increase Kaulbach’s melt flow rate to the claimed range, when doing so would necessarily involve altering the inventive concept of a narrow molecular weight distribution polymer.  The Court held that this is particularly true in light of the fact that the Kaulbach reference appears to teach away from broadening molecular weight distribution and the known methods for increasing melt flow rate.

Specifically, Kaulbach includes numerous examples of processing techniques that are typically used to increase melt flow rate, which Kaulbach cautions should not be used due to the risk of obtaining a broader molecular weight distribution.

These factors do not demonstrate that a POSA would have had a “reason to attempt” to get within the claimed range, as is required to make such an obviousness finding.

As Chemours persuasively argues, the Board needed competent proof showing a skilled artisan would have been motivated to, and reasonably expected to be able to, increase the melt flow rate of Kaulbach’s polymer to the claimed range when all known methods for doing so would go against Kaulbach’s invention by broadening molecular weight distribution.

The CAFC therefore held that the Board relied on an inadequate evidentiary basis and failed to articulate a satisfactory explanation that is based on substantial evidence for why a POSA would have been motivated to increase Kaulbach’s melt flow rate to the claimed range, when doing so would necessarily involve altering the inventive concept of a narrow molecular weight distribution polymer.

  • Commercial success

In addition, Chemours argued that the Board legally erred in its analysis of objective indicia of nonobviousness finding an insufficient nexus between the claimed invention and Chemours’s commercial polymer, and its requirement of market share evidence to show commercial success.

Specifically, Chemours argued that the Board improperly rejected an extensive showing of commercial success by finding no nexus on a limitation-by-limitation basis, rather than the invention as a whole. Chemours contended that the novel combination of these properties drove the commercial success of Chemours’s commercial polymer. Second, Chemours argued the Board improperly required Chemours to proffer market share data to show commercial success.

The CAFC held that contrary to the Board’s decision, the separate disclosure of individual limitations, where the invention is a unique combination of three interdependent properties, does not negate a nexus. The Court recognized that concluding otherwise would mean that nexus could never exist where the claimed invention is a unique combination of known elements from the prior art.

Further, the Court held, quoting prior caselaw, that the Board, erred in its analysis that gross sales figures, absent market share data, “are inadequate to establish commercial success.”

“When  a  patentee  can  demonstrate  commercial  success, usually shown by significant sales in a relevant market, and that the successful product is the invention disclosed and claimed in the patent, it is presumed that the commercial success is due to the patented invention.”  J.T. Eaton & Co. v. Atl. Paste & Glue Co., 106 F.3d 1563, 1571 (Fed. Cir. 1997); WBIP, 829 F.3d at 1329.  However, market share  data,  though  potentially  useful,  is  not  required  to  show commercial success.  See Tec Air, Inc. v. Denso Mfg. Mich. Inc., 192 F.3d 1353, 1360–61 (Fed. Cir. 1999).

The CAFC therefore reversed the Board’s finding of obviousness of the ‘609 and ‘431 claims at issue.

  • Dissent

Judge Dyk dissented in part as to the strength of the teaching away by Kaulback.  Specifically, he noted that Kaulbach’s copolymer is nearly identical to the polymer disclosed by claim 1 of the ’609 patent. The only material difference between claim 1 and Kaulbach is that Kaulbach discloses (in Sample A11) a melt flow rate of 24 g/10 min, slightly lower than 27 g/10 min, the lower bound of the 30 ± 3 g/10 min rate claimed in claim 1 of the ’609 patent.

As to the teachings of Kaulbach, he went on to note that even though Kaulbach determined that “a narrow molecular weight distribution performs better,” it expressly acknowledged the feasibility of using a broad molecular weight distribution to create polymers for high speed extrusion coating of wires. Hence, Judge Dyk concluded that this is not a teaching away from the use of a higher molecular weight distribution polymer.

Contrary to the majority’s assertion, modifying the molecular weight distribution of Kaulbach’s disclosure of a 24 g/10 min melt flow rate to achieve the 27 g/10 min melt flow rate of claim 1 would hardly “destroy the basic objective” of Kaulbach as the majority claims.

Take away

  • There must be clear motivation for a POSA to modify a claimed range even to a small extent.  Evidence within the prior art that such a modification would not be beneficial maybe a sufficient teaching away and can negate a finding of increasing the range as an obvious modification.  Patent prosecutors should be more assertive in requiring a clear showing of reasons to make a modification of increasing a range outside of a prior art’s taught range.

Whose Burden Is It?

| September 19, 2018

DuPont, Archer Daniels v. Synvina

September 17, 2018

Before Lourie, O’Malley and Chen.  Opinion by Lourie, joined by O’Malley and Chen.


DuPont and ADM filed an inter partes review petition against Synvina’s ‘921 patent that claims a method for making 2,5-furan dicarboxylic acid (FDCA), which is useful as bio-mass.  The Board ultimately held that DuPont had failed to prove that the ‘921 patent was obvious over the prior art.  On appeal, the CAFC reversed, finding that the Board had incorrectly failed to shift the burden of production, from DuPont to the patentee Synvina and had misapplied the standard for finding whether variables are result-effective.

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CAFC relies on extrinsic evidence to define a claim term and to demonstrate inherency

| February 23, 2018

Monsanto Technology LLC v. E.I. Dupont de Nemours & Co.

January 5, 2018

Before Dyke, Reyna and Wallach.  Opinion by Wallach.


 In this case, the CAFC affirmed a PTAB decision which relied on two pieces of extrinsic evidence.  First, a journal article referred to by the specification was used to define the bounds of “about 3% or less.”  Second, a Declaration submitted in the course of inter partes reexamination was used to demonstrate that claimed features are inherent in an anticipating reference.  The CAFC explained that both were appropriate, and the claims are invalid as being anticipated by the cited art.

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Beware of Relying on a Single Example, Since It May Limit Claim Scope

| October 17, 2013

Sunovion Pharmaceuticals, Inc. v. Teva Pharmaceuticals, et al.

September 26, 2013

Panel:  Lourie, Schall and Reyna.  Opinion by Lourie


In this case arising from an ANDA, the claims recited the vague term of “essentially free of”, which was undefined by the specification.  Although probably never intended to limit the scope of the claims, the CAFC held that the content of the sole substantive example in the specification and a declaration citing this—which was heavily relied upon during prosecution—defined the scope of this ambiguous term.  However, the patent owner managed to win the litigation nonetheless, due to the CAFC recognizing the ineffectiveness of an unconventional “certification” of non-infringement to the district court which contradicted the defendant’s FDA filing.

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Can an open-ended claim range be enabled?

| August 22, 2012

Magsil Corp. and MIT v. Hitachi Global

August 14, 2012

Panel:  Rader, O’Malley, Reyna.  Opinion by Rader.


The U.S. District Court for the District of Delaware granted summary judgment finding claims 1-5, 23, 26 and 28 of appellants’ U.S. Patent No. 5,629,922 (the ‘922 patent) invalid as a matter of law for lack of enablement and therefore non-infringed.  At issue was whether the specification enabled the broad scope of the claimed “open-ended” range of values having a lower threshold, but no upper limit, defined by “a change in the resistance by at least 10% at room temperature”.

Magsil appealed the district court’s decision.  On appeal, the CAFC affirmed the district court’s finding that claims 1-5, 23, 26 and 28 of the ‘922 patent are invalid for lack of enablement.

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Another per se rule bites the dust. A reference that discloses a range encompassing a somewhat narrower claimed range may not be sufficient to establish a prima facie case of obviousness

| April 12, 2012

Genetics Institute, LLC v. Novartis Vaccines and Diagnostics, Inc.

August 23, 2011

Panel:  Lourie, Plager and Dyk.  Opinion by Lourie.  Concurrence-in-part and dissent-in part by Dyk.


This article concludes a three-part series regarding this important case from last year.   For part 1, click here.  For part 2, click here.  This final article discusses the following questions:

Question 1:  Does a broad range necessarily render obvious a narrower range falling within that broader range?

Answer 1:  No.

Question 2:  Do all minor chemical differences always lead to a conclusion of obviousness?

Answer 2:  No.

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