April 25, 2024by Richard Treanor

On April 17, 2024, the Patent Trial and Appeal Board in Ex parte Sanada (Appeal 2023-002165) affirmed an examiner’s single-reference obviousness rejection of a claim to a magnetic material comprising magnetic particles and an intercalated phase and requiring an angle of orientation between the magnetic particles and the plane of the material to be 10° or less.

In attacking the prima facie case, Appellant argued that the applied reference did not suggest the claimed combination of particularities concerning each of the magnetic particles, the intercalated phase, and the angle of orientation, and urged that the data in the specification demonstrated “unexpectedly favorable strength and magnetic properties for their inventive Examples in contrast to Comparative Examples.”

Appellant’s first argument was dismissed by the Board in view of the reference’s disclosure of overlapping ranges for each limitation, citing In re Peterson, 315 F.3d 1325 (Fed. Cir. 2003) (“A prima facie case of obviousness arises when the ranges of a claimed composition overlap the ranges disclosed in the prior art.”). In dismissing the second argument – that data in the specification demonstrated unexpected results – the Board reviewed the specification and found it lacking:

Here, Appellant’s unexpected results are not supported by factual evidence. The Specification’s description of Figures 11–13 and Tables 1 and 2 does not describe the inventive Examples as demonstrating results that are unexpected. For instance, paragraphs 110–112 of the Specification do not describe the results shown in Figures 11–13 as unexpected and paragraph 166 merely states that results provided in Table 2 are “excellent” and “remarkable effects are obtained.” Therefore, Appellant’s assertions that the results are unexpected are supported only by attorney argument and conclusory statements in the Specification, which are insufficient.

and in a final blow noted that Appellant had not addressed whether the asserted unexpected results provided a comparison with the closest prior art. Rejection affirmed.

What could Appellant have done differently? They could have filed a Declaration supporting their contentions and providing the (apparently available) data in the form of evidence sufficient to overcome the rejection. As noted in In re Soni, 54 F.3d 746 (Fed. Cir.1995), cited by the Board in this appeal, “when an applicant demonstrates substantially improved results, as Soni did here, and states that the results were unexpected, this should suffice to establish unexpected results in the absence of evidence to the contrary (emphasis in original).” Because it is unusual for a patent specification to describe data as unexpected, the filing of a Declaration providing this statement and explaining the importance of the results can oftentimes mean the difference between allowance and rejection.


March 25, 2024by Yanhong Hu

In Ex parte Perrot-Simonetta (Appeal 2023-000358), the Patent Trial and Appeal Board (“the Board”) reversed the Examiner’s obviousness rejection based on the principle of inherency.  

The claim at issue was directed to a steel part having a particular elemental composition and microstructure and exhibiting certain properties. Specifically, in addition to the specific mechanical strength, elastic limit, and breaking elongation, the claimed steel part had “a constriction at break greater than 30%.” 

The Examiner rejected the claim as obvious over Gao in view of Resiak and Han. The Examiner admitted that Gao was silent towards the constriction at break value but reasoned that since Gao described steel having overlapping composition, microstructure, and other mechanical properties, one skilled in the art would have found Gao’s steel necessarily had the recited constriction at break value. The Examiner additionally cited Resiak and Han, which described steel having the recited constriction at break value and admittedly “similar” but not identical compositions, to support her inherency/obviousness position.  

The Appellant argued that Resiak and Han provided evidence showing that Gao’s steel did not necessarily possess the characteristics of the claimed product, and thus rebutted, not supported, the Examiner’s allegedly prima facie case. In particular, the Appellant noted that Resiak described a steel with the recited mechanical strength and constriction at break value but not the recited breaking elongation value. The Appellant further noted the different processing parameters for steel described in Gao, Resiak, and Han and argued that the secondary references could not provide any information on the constriction at break value of Gao.  

The Board agreed with the Appellant and held that the combined prior art teaching did not support the Examiner’s finding that the recited properties were necessarily present in Gao’s steel. Judge Owens further noted in his concurring opinion that the Examiner had exercised impermissible hindsight.  

Takeaway:  A prima facie case of either anticipation or obviousness is established when the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes. However, as shown in Perrot-Simonetta, mere overlap in composition and structure may not be sufficient to establish that the claimed and prior art products are identical or substantially identical in structure or composition.  

Judges: Terry J. Owens, Catherine Q. Timm, and Lilan Ren 


March 17, 2023by Matthew Barnet

Two recent cases – one at the PTAB and one at the Federal Circuit – illustrate key considerations in determining whether a nature-based product is patent eligible under 35 U.S.C. §101.

In ex Parte Ronchi, the PTAB reversed an examiner’s rejection of claims as patent ineligible under §101. Independent claim 13 recited:

A powder solid composition comprising at least one phospholipid and a hydroalcoholic extract of Bergamot fruit containing flavonoids, neoeriocitrin, naringin and neohesperidin as the only extract.

The examiner found that claim 13 was directed to a “product of nature, namely naturally occurring compounds found in Bergamot fruit.” The examiner acknowledged that the recited hydroalcoholic extract was not found in nature, but argued that isolation or purification by itself “does not result in a product which is ‘markedly different’ from the naturally-occurring component.”

The appellant acknowledged that the components in claim 13 were naturally occurring, but argued that the claimed powder solid composition “is a physical form distinct from any of the naturally-occurring sources of the claimed composition.” The appellant also argued that the combination of phospholipid with the hydroalcoholic extract provided a markedly different characteristic (improved bioavailability of at least naringin and neohesperidin) compared to the extract alone.

The PTAB agreed with the appellant. Citing the Supreme Court case of Myriad, the PTAB acknowledged that “claiming a natural product that is merely separated from elements found in its natural environment, where the structure of the natural product is not otherwise altered, does not support a conclusion that the isolated product is patent eligible.” However, the PTAB noted that “the mere fact that the components of the claimed composition are all nature-based does not end the inquiry as to whether the claimed composition recites a judicial exception.” Instead, according to Myriad (and Chakrabarty) it is necessary to evaluate the claimed composition for “markedly different characteristics from any found in nature.”

In analyzing the composition of claim 13 for markedly different characteristics, the PTAB explained that it “must compare the characteristics of the claimed nature-based composition to its naturally occurring counterpart in its natural state, in order to determine whether the characteristics of the claimed nature-based product are markedly different.” The PTAB thus looked for the appropriate naturally occurring counterpart.

The PTAB did not consider Bergamot fruit itself to be an appropriate naturally occurring counterpart.[1] Instead, it considered the appropriate counterpart to be a composition containing the components recited in the extract: flavonoids, neoeriocitrin, naringin and neohesperidin. The PTAB disagreed with the examiner’s finding that Bergamot fruit extract could contain the phospholipid lecithin. Accordingly, the PTAB “determine[d] that claim 13 recites two nature-based compositions: (1) the extract having flavonoids, neoeriocitrin, naringin, and neohesperidin, and (2) the phospholipid.”

The PTAB then looked at the appellant’s comparison of the claimed composition (combining the extract and phospholipid) to the extract alone. Data in the specification showed improved bioavailability of naringin and neohesperidin when provided in the claimed composition (extract + phospholipid) compared to when provided in the extract (without the phospholipid).

These data persuaded the PTAB that the claimed composition possessed markedly different characteristics from a naturally occurring counterpart composition, and thus that the claimed composition was patent eligible under §101. Accordingly, the PTAB reversed the examiner’s rejection.

In a different recent case, ChromaDex, Inc., Trustees of Dartmouth College v. Elysium Health, Inc., the Federal Circuit found claims to a nature-based product to be ineligible under §101.

Claim 1 in ChromaDex recited:

A composition comprising isolated nicotinamide riboside [NR] in combination with one or more of tryptophan, nicotinic acid, or nicotinamide, wherein said combination is in admixture with a carrier comprising a sugar, starch, cellulose, powdered tragacanth, malt, gelatin, talc, cocoa butter, suppository wax, oil, glycol, polyol, ester, agar, buffering agent, alginic acid, isotonic saline, Ringer’s solution, ethyl alcohol, polyester, polycarbonate, or polyanhydride, wherein said composition is formulated for oral administration and increased NAD+ biosynthesis upon oral administration.

The court found that claim 1 read on milk[2] as a naturally occurring product, with the only difference being that NR is not “isolated” in milk. As the PTAB did in Ronchi above, the court relied on the Supreme Court cases of Myriad and Chakrabarty in analyzing patent eligibility under §101.

The court found that “the act of isolating the NR compared to how NR naturally exists in milk is not sufficient, on its own, to confer patent eligibility. The claimed compositions remain indistinguishable from natural milk because, other than separation from some other components, the isolated NR is no different structurally or functionally from its natural counterpart in milk.”

The appellant argued that the claimed compositions were advantageous compared to milk because the isolation of NR allowed for significantly more NAD+ biosynthesis than provided by milk. However, the court found that the “claims do not require any minimum quantity of isolated NR. Nor do these claims attribute the claimed increase in NAD+ biosynthesis to the isolated NR, requiring only that the composition increase NAD+ production.” The court reasoned that “[b]ecause milk increases NAD+ biosynthesis, the claimed compositions do not possess characteristics markedly different from those found in nature.” The court concluded that “[t]he claimed compositions do not exhibit markedly different characteristics from natural milk and are, therefore, invalid for claiming a patent-ineligible product of nature.” Accordingly, the court found the claims invalid under §101.

Takeaway: Claims reciting nature-based products, i.e., products whose components are naturally occurring, face scrutiny under §101. Under the framework of Myriad and Chakrabarty, The USPTO and courts analyze these claims to determine if the claimed product possesses “markedly different characteristics” from a corresponding naturally occurring product. If such characteristics are shown (as in Ronchi) then the claims can be found patent eligible under §101. However, if such characteristics cannot be shown (as in ChromaDex) then the claims will be found patent ineligible.

[1] If it had done so, would it have found that cells in the fruit contained phospholipids in their membranes, and thus that the fruit itself contained each of the components recited in claim 13, even if not the specific phospholipids recited in dependent claim 21?

[2] Milk is a composition containing NR (but not “isolated” NR), tryptophan and nicotinamide, in admixture with a sugar (lactose). Milk is formulated for oral administration, and (through tryptophan) increases NAD+ biosynthesis upon consumption.



February 16, 2023by Richard Treanor

In the 1960s the Federal Circuit’s predecessor court, the Court of Customs and Patent Appeals (CCPA), established a “flavor” of anticipation that did not require an example – when a reference was so limited and specific in its disclosure that one of ordinary skill in the art was able to “at once envisage” the specific compound, method, etc., claimed, that claim was anticipated by the reference. On December 20, 2022, the Patent Trial and Appeal Board (PTAB) in Ex parte Mizushima (Appeal 2022-003863) extended this theory of anticipation to a secondary, academic use of an “envisioned” composition.

In Mizushima the claim was directed to a powdered coloring material comprising at least one pigment selected from three protein-based pigment candidates in combination with at least one of three chelating agents. The prior art cited described an academic study of the influence of temperature, pH, and preservatives on one of the claimed pigment candidates, all conducted in solution. Eight preservatives were used, one of which was a claimed chelating agent (citric acid), used in solution in a claimed weight ratio. In addition to the solution studies, the paper provided a microstructure analysis on dried solutions of the pigment with two of the preservatives – sugar, described as being known for stabilizing proteins, and salt.

In affirming the examiner’s rejection, the Board acknowledged that the reference failed to make a solid composition comprising the pigment and citric acid in the claimed amounts, but took the position that one of ordinary skill “would have readily recognized or inferred” such a solid composition as emanating from the described solution using citric acid given the description of dried solutions using sugar and salt.

Ex parte Mizushima thus extends traditional “Petering” anticipation, which typically arises when an examiner chooses a combination of ingredients from a limited list to provide a claimed composition, to include different physical forms of ingredient combinations described in a reference for the purpose of academic study. That is, in a typical “Petering” situation the examiner constructs the anticipatory composition for the same reason the inventors did – to cure a disease, to treat a surface, to add to gasoline, etc. Here, the only reason the authors dried two of their solutions was academic curiosity – to see how two of their preservatives coated the pigment. Would the Federal Circuit agree with the Board that academic curiosity is sufficient motivation for one of ordinary skill to “at once envisage” a new form of a described material?

Judges: Hastings, Colaianni, Kennedy


February 3, 2023by Jacob Doughty

Ex parte Fox is a recent decision of the Patent Trial and Appeal Board (PTAB) addressing the interpretation of a Markush group in a claim rejected for anticipation and obviousness.  

The claim at issue was directed to “[a] cleaning solution comprising one or more solvents selected from the group consisting of acetoacetates, alcohols, glycol ethers, glycol esters, terpenes, and water…” The claim also required other components and properties. 

The examiner identified a cleaning solution in the prior art which included some of the solvents listed in the claim. However, the prior art cleaning solution required a further solvent, “at least one oxyisobutyric acid ester.” The examiner asserted that, although at least one of the listed solvents must be present, the “comprising” language in the claim permitted the presence of additional solvents in the cleaning solution.  

The examiner supported his position by citing MPEP 2111.03.II, which, in turn, cites In re Crish, 393 F.3d 1253 (Fed. Cir. 2004). The examiner relied on the following description of the Crish case from the MPEP:  

In determining the scope of applicant’s claims directed to “a purified oligonucleotide comprising at least a portion of the nucleotide sequence of SEQ ID NO:1 wherein said portion consists of the nucleotide sequence from [521] to 2473 of SEQ ID NO:1…” the court stated that the use of “consists” in the body of the claims did not limit the open-ended “comprising” language in the claims… 

The PTAB stated that a case cited in the same paragraph of the MPEP relied on by the examiner, Multilayer Stretch Cling Film Holdings, Inc. v. Berry Plastics Corp., 831 F.3d 1350, (Fed. Cir. 2016), included a fact pattern much closer to the claim on appeal. The PTAB stated that Crish was distinguishable from the claims on appeal, because Crish did not involve a Markush group of distinct alternatives from which to select. 

Relying on the Multilayer case, the PTAB noted that the use of the transitional phrase “consisting of” to set off a patent claim element creates a very strong presumption that that claim element is closed and therefore excludes any elements, steps, or ingredients not specified in the claim. Thus, if a patent claim recites “a member selected from the group consisting of A, B, and C,” the member is presumed to be closed to alternative ingredients D, E, and F. In the claim on appeal, the “member” was the “solvent,” so the claim was closed to solvents other than those specifically recited in the Markush group – even though the claimed cleaning solution was open to containing other non-solvent elements. 

When the claim on appeal was properly construed, the prior art was not sufficient to anticipate or render obvious the claim, because the prior art required the presence of “at least one oxyisobutyric acid ester” solvent, i.e, a solvent that was not recited in the Markush group of the claim.  

Takeaway: Markush groups are frequently used to define components of composition. It is important to be intentional when drafting Markush group to control what is within and outside the scope of the claim. In thinking about a claim drafted in typical Markush format, “an X selected from the group consisting of A, B, and C,” attention is often focused on A, B, and C, which define what must be present. However, care must be taken in defining X which indicates what will be excluded from the claim. A broad X may define over the prior art but may also make design-around compositions easy to identify.  

Judges: Cashion, McGee, Inglese


January 20, 2023by Matthew Barnet

U.S. examiners often combine two or more references in making an obviousness rejection. Sometimes, a possible argument against obviousness is that there would not have been a reasonable expectation of success in combining the references in the way proposed by the examiner. When making such an argument, however, applicants might inadvertently raise the issue of enablement. The recent case of Ex parte During (Appeal No. 2022-000776) illustrates this situation.

Independent claim 1 in During recited:

A method of treating narcolepsy comprising administering to a patient in need thereof a pharmaceutical composition comprising 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridine-3-ol (gaboxadol) or a pharmaceutically acceptable salt thereof.

The examiner rejected claim 1 as obvious based on a combination of two references: Walsh and Abad. Walsh taught that the drug gaboxadol enhances slow wave sleep (SWS). Abad taught that certain SWS-enhancers are effective to treat narcolepsy. Combining these references, the examiner found that it would have been obvious to treat narcolepsy with gaboxadol.[1]

The applicant argued that there would not have been a reasonable expectation of success in combining the cited references to obtain the claimed methods. For example, Abad indicated that it was unclear whether SWS enhancement was the appropriate mechanism for treating narcolepsy, and that the effectiveness of any one compound was uncertain until tested. The applicant further explained that the SWS-enhancers used in Abad bound to a different receptor than gaboxadol, and therefore acted by a different mechanism.

The PTAB agreed with the applicant. It found that the cited references “merely render[] gaboxadol obvious to try in a method to treat narcolepsy.” However, “Abad does not provide specific guidance as to how gaboxadol may be used to treat narcolepsy, concluding instead that ‘[m]ore research is needed to determine the usefulness of [other potential SWS enhancers] in consolidating nocturnal sleep in narcolepsy patients.’” The PTAB cited Abad’s conclusions that “[n]arcolepsy remains a complex disease whose cure remains elusive despite our expanding knowledge about its pathophysiology” and that “[d]isease-specific therapies need further development and testing before they can be clinically relevant.”

Finding that there would not have been a reasonable expectation of success in combining Walsh and Abad to obtain the claimed methods, the PTAB reversed the obviousness rejections.

However, the PTAB issued a new ground of rejection: lack of enablement.

The PTAB noted that independent claim 1 was narrow in terms of the drug (gaboxadol or pharmaceutically acceptable salts) and disease treated (narcolepsy). However, the PTAB explained that “the Specification not only lacks any working examples regarding treatment of narcolepsy using gaboxadol, but also provides only the most generic teachings regarding, e.g., the dosage, route, and/or timing or frequency of administration.” The PTAB cited Abad’s teaching that narcolepsy is “a complex disease whose cure remains elusive despite…expanding knowledge about its pathophysiology,” and found that “a significant quantity of experimentation would have been required to carry out the claimed method.”

Thus, the same teachings from the references used by the applicant to argue against obviousness were used by the PTAB to argue against enablement. Although the PTAB reversed the obviousness rejections, it found the claims not to be enabled.

Takeaway: Applicants should be careful when addressing obviousness rejections by arguing that there would not have been a reasonable expectation of success in combining references, since such an argument might open the door to an enablement rejection. That is, if the applicant argues that the references do not provide sufficient guidance for a skilled artisan to obtain the claimed invention, the applicant should be ready to explain how a skilled artisan could practice the claimed invention based on guidance from the specification.

Judges: Fredman, Jenks, Chang

[1] The examiner also made a second obviousness rejection, over Walsh in view of Mignot, where Mignot was cited for its teaching that SWS-enhancers are effective to treat narcolepsy, similar to the teaching in Abad.


December 1, 2022by Yanhong Hu

In Ex parte Langenfeld (Appeal 2021-004075), the Examiner rejected the claims as obvious over a combination of prior art references and based on the theory of design choice. The Patent Trial and Appeal Board (“Board”) reversed.  

The invention at issue was directed to a method of producing rolled food products that included a step of cutting a dough sheet to form a roll sheet having a continuous pattern comprised of “an asymmetrical repeat unit.” 

Wolf, the primary reference found by the Examiner, described a method of producing croissants. As admitted by the Examiner, Wolf did not disclose a cutting pattern that would produce an asymmetrical repeat unit. The Examiner then turned to Mel, which described making homemade crescent rolls. Mel disclosed cutting a circular dough into triangles and described that it was all right if the “triangles aren’t all perfect” because “[that] is something special about home cooking – it is not all perfect and rigid.” The Examiner thus concluded that “it would have been obvious to form the triangles and subsequently the rolls of Wolf as slightly asymmetrical in order to create a ‘homemade’ appearance that is special and pleasing to consumers.” The Examiner further contended that the claimed asymmetrical repeating unit shape was merely an obvious matter of design choice, alleging that the shape and symmetry of the rolls would have been obvious to adjust in the absence of a demonstration of criticality. 

However, the Board found that, at best, Mel only suggested random variations, not “asymmetrical repeat units” as required by Appellant’s method. Thus, the Board agreed with Appellant that not only the resulting arrangement of Wolf as modified by Mel failed to meet the claim limitation, but Mel was “directly contrary to the Examiner’s conclusion that all the produced rolls would be the same and have the same asymmetry” in that Mel equated the homemade look to imperfection.  

With respect to the Examiner’s allegation of obvious design choice, the Board noted that Appellant provided evidence showing that the asymmetrical repeating unit was significant to the invention (specifically, it was possible to retain a symmetrical outer appearance despite that each of crescent rolls had a different amount of dough at each end) and was more than one of the numerous configurations a skilled artisan would have found obvious for the purpose of forming rolled dough products. Because the prior art had no suggestion for changing the shape to any asymmetrical repeating unit shape, the Board found the evidence provided by Appellant was sufficient to prove non-obviousness. In addition, the Examiner did not adequately rebut Appellant’s evidence of significance. Therefore, the Board held that Appellant need not show the criticality of the change in shape for unexpected results and reversed the Examiner’s obviousness rejection.  

Takeaway: When a claim feature cannot be found in prior art, examiners may apply the theory of “design choice” and often also request applicants to provide evidence of criticality to overcome an obviousness rejection based on design choice. Langenfeld, again, clarifies that evidence of criticality is not necessary under such circumstances if applicants provide unrebutted evidence of significance. Examples of evidence of significance include a different function associated with the claim feature, a stated problem solved by the claim feature, and improvements, advantages, and benefits of the claim feature (see also one of our previous posts here). Such evidence can be found in applicant’s specification and/or prior art or can be provided in the form of a declaration during examination.  

JudgesC. Q. Timm, G. C. Best, and N. W. Wilson 


October 4, 2022by Matthew Barnet

In Ex parte Makarova (Appeal No. 2022-002730), the examiner rejected the claims as obvious based on a combination of references. The PTAB reversed, finding important differences between two references suggesting they should not be combined in the way proposed by the examiner.

Independent claim 1 recited:

A microfilter comprising:

a single polymer layer formed from an epoxy-based negative photo-definable dry film, wherein the single polymer layer has a flexibility to be disposed on a roll and unrolled; and

a plurality of apertures formed by exposing the single polymer layer to a UV light via an optical mask to obtain a selected shape of said apertures based on said mask, each of said apertures extending through the single polymer layer having said flexibility,

said single polymer layer having said flexibility forming a freestanding unattached microfilter structure with uniform thickness and having said flexibility.

The examiner found that the primary reference (Wolfe) described most of the limitations of claim 1. For example, Wolfe described a particulate filter with regularly spaced micropores, which comprised a single flexible polymer layer formed from a photo-definable dry film (MYLAR). The single polymer layer in Wolfe had flexibility sufficient to be disposed on a roll and unrolled, and its apertures were formed by exposing the single polymer layer to radiation via an optical mask. The single polymer layer also formed a freestanding, unattached microfilter structure with a uniform thickness.

However, the film in Wolfe was not an epoxy-based film, as recited in claim 1. The examiner turned to a secondary reference (DuPont) for this limitation.

The examiner found that DuPont described a flexible epoxy-based negative photo-definable dry film that had excellent thickness uniformity after hot roll lamination. The examiner found that it would have been obvious to substitute the film from DuPont into Wolfe’s system because both references related to microfabricated polymer membrane structures.

The applicant argued that such a substitution would not have been obvious. In particular, the applicant noted that DuPont’s film was “best suited for permanent applications where it is imaged, cured and left on devices” rather than being a freestanding unattached structure as recited in claim 1. Additionally, the excellent thickness uniformity after hot roll lamination in DuPont was premised on the film being laminated to a substrate, rather than being freestanding.

The PTAB sided with the applicant. The PTAB found that “because DuPont specifically indicates that its film is best used while laminated to an underlying substrate, a person of skill in the art would not have thought that film to be a substitute for Wolfe’s freestanding polymeric sheet.” The PTAB concluded that “the Examiner’s rationale as to why a person of skill in the art would have substituted DuPont’s film for Wolfe’s polymeric sheet is not adequately supported by the evidence of record.” Accordingly, the PTAB reversed the obviousness rejection.

Takeaway: Obviousness rejections often involve a primary reference describing most of the claimed elements, with a secondary reference used to fill in gaps in the primary reference. When an examiner takes the position that it would have been obvious to substitute an element from the primary reference with an element from the secondary reference, it is worth challenging that position if there is a good reason not to make such a substitution.

Judges: Housel, Best, Wilson


September 9, 2022by Jacob Doughty

Ex parte Ihn is a recent decision of the Patent Trial and Appeal Board (PTAB) addressing obviousness and enablement of a claim directed to an organic light-emitting device – particularly to a compound present in the emission layer of the device. Interestingly, the primary reference in the appealed obviousness rejection, Endo, originated from an anonymous third-party submission.

The claim at issue was directed to an organic light-emitting device comprising, inter alia, an emission layer comprising a thermally activated delayed fluorescence (TADF) emitter and a host (two different compounds). The TADF emitter was required to provide particular emission characteristics in use and to have a structure defined by a generic chemical formula.

Endo disclosed specific compounds that were also disclosed in applicant’s specification as TADF emitters. The claim as filed did not require a specific structure for the TADF emitter – merely that the TADF emitter provide the particular emission characteristics. Based on the commonly disclosed compounds, the third-party submitter – and subsequently the examiner – asserted that the claim was unpatentable (identical compounds have identical properties). During prosecution, applicant added the generic chemical formula which excluded the specific compounds disclosed in the primary reference.

The examiner then took the position that a generic formula in Endo encompassed structures falling within the scope of that amended claim, notwithstanding that no specific compound within the scope of the claim was disclosed in Endo. Applicant countered by arguing that the claim required that a linking group be present between, e.g., an indolocarbazole group and a heteroaromatic group:

“… L1 is selected from: a cyclopentane group, a cyclohexane group… a1 is an integer from 1 to 5…”

while the structural formula from Endo relied on by the examiner required a single bond:


While the structural formula from Endo showed connection via a single bond, and most of the exemplary compounds in Endo were connected via a single bond, some exemplary compounds in Endo included an aromatic heterocyclic group indirectly attached to an indolocarbazole skeleton by way of a hydrocarbon group. (This was not inconsistent with the description of Endo’s structural formula, in which polycyclic groups having both aromatic and heteroaromatic rings could be “Ar”).

In view Endo’s disclosure of some compounds in which an aromatic heterocyclic group was indirectly attached, the PTAB found that this “… would have indicated to one of ordinary skill in the art that those structures provide the possibly improved delayed fluorescence emission efficiency and appropriate positional relationship for intermolecular conformation Endo desires from the compounds within…” the structural formula. Thus, the obviousness rejection was affirmed.

With respect to enablement, the examiner argued that the claim covered innumerable combinations of TADF emitters and hosts and that it would have required an undue amount of experimentation to identify combinations of TADF emitters and hosts that provided the claimed emission characteristics. The PTAB declined to adopt the examiner’s reasoning with respect to enablement. The PTAB noted that a large amount of experimentation is not necessarily undue, and the examiner had provided no evidence to support her assertion: “[t]he Examiner’s mere assertions to that effect are insufficient to establish a prima facie case of nonenablement.”

Takeaway: Third-party submissions provide mixed results – sometimes an examiner will rely heavily on the submitted information, and other times it seems that the submitted information has not been carefully considered by the examiner. However, in this case, the third-party submission led to a PTAB finding of unpatentability. This case shows that third-party submissions should not be ignored (particularly in view of their relative low cost) as part of a strategy for influencing the scope of a competitor’s patents.

Compounds are often defined in claims with generic formulae encompassing large numbers of specific compounds. This creates a tension between arguing about what the prior art fairly suggests and arguing about what your own specification fairly enables. It is important to take some care when arguing that prior art does not provide sufficient guidance to lead a skilled artisan to a claimed genus of compounds – particularly if the prior art’s disclosure is not significantly less robust than the disclosure of your own specification.

Judges: Owens, Hastings, Range


August 26, 2022by Beau Burton

Ex parte Bhatnagar is a recent decision in which the Patent Trial and Appeal Board (PTAB) reversed an obviousness rejection because the Examiner’s reason for modifying the prior art was not commensurate with the underlying disclosure.

The claims in Bhatnagar were directed to a system that included a maintenance pet food having a density from 400 g/l to 600 g/l and a reduced caloric pet food having a density from 300 g/l to 450 g/l.

The primary reference, Pan, disclosed a system with a maintenance pet food and a reduced caloric pet food, but did not mention densities. To remedy this deficiency, the Examiner relied on a secondary reference, Mao, and argued it would have been obvious to have a “density in the range of 200–600 g/l because the pet food has significantly improved palatability.” The PTAB disagreed.

The Board rejected the Examiner’s position because the improved palatability described by Mao was expressly tied to another feature. Specifically, Mao taught:

It is well-known in the art to incorporate palatability enhancing ingredients in dry pet food [products] to increase the palatability thereof and to make them more appealing to pets…. palatability of certain dry pet food products can be improved significantly by coating the food product with a covering layer that contains dry yeast extract, edible phosphate salt[,] and optionally other edible components.

According to the PTAB, the Examiner improperly associated the improvement in palatability, which was expressly tied to the presence of a covering layer, with the density.

Thus, while Mao broadly disclosed a pet food having a bulk density of 200–600 g/l (overlapping with each of the claimed ranges), the PTAB found the Examiner failed explain why, given the teachings of Mao, one of ordinary skill in the art would have been prompted to make the proposed modification to Pan’s food composition density. With no other reason for the modification evident from the record, the PTAB reversed the obviousness rejection.

Takeaway: Ex parte Bhatnagar embodies the recognition from KSR that “a patent composed of several elements is not proved obvious merely by demonstrating that each of its elements was, independently, known in the prior art.” Beyond that, Bhatnagar shows that an Examiner cannot arbitrarily associate benefits and features in the prior art to arrive at a motivation to modify. Here, the density of the pet food had nothing to do with the benefit cited by the Examiner. This is why it is important to verify and, when appropriate, challenge the accuracy of an Examiner’s characterization of the prior art.

Judges: J. Bahr, P. Kauffman, S. O’Hanlon