PTAB Archives - Page 3 of 13

Nine times out of ten a negative limitation satisfies the written description requirement when the specification positively describes the limitation to be excluded or better yet provides a reason to exclude the limitation. The rationale for the former being that a description of the whole, necessarily describes the part remaining. For instance, when the specification discloses a composition that includes an additive selected from A, B, and C, there is support for a composition that does not include A, B, or C.

Satisfying the written description requirement without a positive recitation of the limitation to be excluded is rare; however, Ex parte Kroepke provides an example in which the Patent Trial and Appeal Board found support for a negative limitation based on silence.

The following claim on appeal is illustrative:

A cosmetic or dermatological preparation, wherein the preparation comprises from 0.01 % to 5 % by weight of at least one red light-filtering dye, at least one white pigment, and from 0.0001 % to 10 % by weight of at least one anti-inflammatory active ingredient which comprises at least one aqueous extract of Glycyrrhiza inflata, and wherein the preparation does not contain strontium cations.

Of note here is that the specification did not positively mention strontium cations, group II cations, or even alkaline earth metals. The closest disclosure of cations appears to be from ingredients in the examples such as magnesium sulphate, sodium citrate, and potassium sorbate. However, Appellant did not rely on these cation containing ingredients. Appellant simply argued that the written description requirement was satisfied because the specification included “sixty exemplified (most diverse) preparations, none of which contains strontium cations.”

The Examiner disagreed, finding Appellant’s disclosure “as a whole does not conceptualize that the preparation should or should not contain strontium cation. Further, as to the sixty examples disclosed in the application, no explicit[] disclosure of strontium cation does not mean that exemplified preparations do not contain strontium cation.”

The Board found Appellant’s position more persuasive in view of the Federal Circuit’s recent Almirall, LLC v. Amneal Pharms. LLC decision, which held:

[A] reference need not state a feature’s absence in order to disclose a negative limitation. Instead, it was reasonable for the Board to find that, in the context of Garrett, a skilled artisan would recognize that the reference discloses a complete formulation—excluding the possibility of an additional active ingredient… It is undisputed that Garrett discloses dapsone formulations that lack adapalene. The Board thus did not err in concluding that Garrett discloses the negative adapalene claim limitation.

28 F.4th 265, 273–274 (Fed. Cir. 2022) (citations omitted).

At first glance, Kroepke appears to extend the rationale from Almirall permitting the exclusion of an additional unrecited active ingredient to the exclusion of any unrecited ingredients. However, upon closer inspection, Kroepke fits the same pattern as Almirall. First, the invention in Kroepke related to “preparations that include a combination of a dye and an anti-inflammatory active ingredient, and particularly to preparations for the prophylaxis and treatment of sun-irritated skin that aid the body’s own repair mechanisms.” Second, the prior art relied upon by the Examiner in Kroepke for an obviousness rejection (which was also reversed by the Board), required the mandatory presence of strontium for its anti-irritation function when used in combinations with ingredients such as moisturizers and anti-inflammatory agents. Consequently, both Kroepke and Almirall support the exclusion of an additional active ingredient where there are exemplary and complete formulations that do not include an additional active ingredient.

Takeaway: Kroepke and Almirall illustrate a continued expansion of negative limitations satisfying the written description requirement to an extent that might not be possible in other jurisdictions. Nevertheless, it is important to keep in mind that Kroepke and Almirall fit a specific pattern in which exemplary compositions include an active ingredient, and the negative limitation relates to another active ingredient. It is unlikely that these holdings can be extended to the exclusion of any ingredient that is not recited in an example.

Notably, Appellant never had the chance to raise or argue the facts of the Almirall decision because it was decided only one month prior to the decision in Kroepke. Thus, the Board’s reliance on Almirall shows it is applying the most recent Federal Circuit precedents.

Judges: D.E. Adams, J. N. Fredman, T. Chang

Functional equivalence is a rationale that examiners often rely on in support of an obviousness rejection. However, as discussed in one of our previous blogs, examiners may misapply the rationale by ignoring the different function or purpose of an allegedly equivalent component disclosed in prior art. A recent decision of the Patent Trial and Appeal Board (“Board”) – Ex parte Takasu (Appeal 2021-001290) – is another illustrative case.

Appellant’s claimed invention in Takasu was a substrate of a single crystal of formula RAMO₄, where, among other things, R could be Sc, A could be Al, and M could be Mg. The claimed RAMO₄ substrate had an epitaxially-grown surface and a satin-finish surface, each having specific surface roughness.

Yoshii, the primary reference relied on by the Examiner, provided a sapphire substrate for epitaxial growth that could be easily polished. The Examiner found that Yoshii as evidenced by Hansen disclosed a sapphire single crystal substrate that allegedly had the claimed roughness on its front and back sides. The Examiner admitted that the sapphire substrate disclosed in Yoshii was not a RAMO₄ substrate. However, the Examiner found a secondary reference, Yoshida, which disclosed ScAlMgO₄ as one of the material options for a single crystalline substrate as a functional equivalent to sapphire for epitaxial growth. The Examiner thus concluded Appellant’s claimed RAMO₄ substrate would have been obvious over Yoshii in view of Yoshida as evidence by Hansen.

Appellant argued that a sapphire substrate and a RAMO₄ substrate were not equivalent to each other in terms of surface polishing properties.

The Board agreed with Appellant and emphasized that, as stated by the Examiner herself, Yoshida merely disclosed ScAlMgO₄ as “a functional equivalent to sapphire for epitaxial growth, but … not for surface polishing properties.”

Because a sapphire substrate is not functionally equivalent to a RAMO₄ substrate in terms of surface polishing properties, the Board found that the Examiner’s reliance upon Yoshida was misplaced and reversed the obviousness rejection.

Takeaway: As cautioned in MPEP § 2144.06 II, the equivalency of a proper substituting equivalent must be recognized in the prior art for the same purpose and cannot be based on applicant’s disclosure or the mere fact that the components at issue are functional or mechanical equivalents. Thus, arguments rebutting an examiner’s obviousness rejection relying on functional equivalence may be successfully advanced by carefully analyzing the function and purpose of substituted and substituting components disclosed in prior art.

Judges: J. T. Smith, B. A. Franklin, and J. R. Snay

U.S. patent claims typically use the terms “comprising” and “consisting of” when reciting components of a composition. “Comprising” indicates that the composition must include the recited components, but also can include unrecited components, while “consisting of” indicates that the composition excludes unrecited components.

The term “comprising” advantageously provides the applicant with broader scope of protection than “consisting of.” However, such breadth sometimes opens claims to additional prior art. In such cases, “consisting of” can be helpful to distinguish the claims from the prior art.

When claims use both “comprising” and “consisting of,” the scope of the claims must be analyzed carefully. This issue is illustrated in the recent case of Ex parte Rankin (Appeal No. 2021-001726).

Independent claim 40 recited (in part) a composition comprising:

(i) a gel base consisting of:

a wax or oil and;

a salt; and

(ii) titanium dioxide, zinc oxide, barium sulfate, or a combination thereof dispersed in the gel base.

The examiner rejected claim 40 as anticipated by two different references disclosing gels containing titanium dioxide. The gels also included polymeric gelling agents. In each case, the examiner took the position that the gelling agent was within the scope of the claim based on the open “comprising” term in the preamble. For example, in one anticipation rejection, the examiner stated that claim 40 “is interpreted to mean that the gel base consists of a wax or oil, and a salt, but it does not exclude addition of other components, such as the block polymers taught by [the cited reference] to make the final…product.”

In contrast, the applicant argued that the closed “consisting of” term excluded the polymeric gelling agents of the prior art. For example, the applicant alleged that the gels of the cited reference “differ structurally from the gel of claims 40-55 due to the latter being composed exclusively of a wax or oil and salt and therefore excluding the polymers…as constituent structural components.”

The PTAB agreed with the applicant. The PTAB acknowledged that “the ‘comprising’ language in the claim allows the mixture of the gel base and titanium dioxide, zinc oxide, barium sulfate or combination to include additional components dispersed in the gel base.” However, due to the “consisting of” language, “the gel base may contain only the recited wax or oil and salt…[W]e do not agree [with the examiner] that the claim language allows for the addition of ingredients to the gel base.” Accordingly, the PTAB reversed the anticipation rejections.

Takeaway: Whenever a claim uses both “comprising” and “consisting of,” the scope of the claim must be analyzed carefully. The closed, “consisting of” term might be intended to exclude a component disclosed in the prior art, but the examiner might take the position that the component is within the claim scope due to the “comprising” term. In such cases, it is important to clearly identify how the components of the prior art correspond to the claim. In Rankin, the applicant successfully argued that the polymeric gelling agent of the prior art was a component of the gel base (thus excluded by the “consisting of” term) rather than a component dispersed in the gel base (which would have been included by the “comprising” term).

Judges: Adams, Grimes, Jenks

Ex parte Nakanishi, is a recent decision of the Patent Trial and Appeal Board (PTAB) addressing obviousness of a claim directed to a steel composition.

The claim at issue recited, in part:

A non-oriented electrical steel sheet having a chemical composition consisting of, in mass%…

Si: 1.0% or more and 4.0% or less;

Mn: 0.10% or more and 3.0% or less…

Al: less than 0.0005%;

Cu: 0.02% or more and less than 0.04%; and

Ca: 0.003% or more and 0.0100% or less…

In asserting obviousness, the examiner cited a single prior art reference disclosing a steel sheet including components and amounts that could overlap with those recited in the claim. Applicant’s arguments focused first on differences between the claimed composition and the prior art composition and then on evidence of unexpected results.

Applicant’s arguments as to composition focused particularly on the amounts of Al, Cu, and Ca in the claims and the prior art reference. Notably, applicant’s ranges of amounts of Al, Cu, and Ca were much narrower than those in the prior art reference.

Component	Claim	Prior Art Reference
Al	Al < 0.0005%	Al ≤ 3%
Cu	0.02% ≤ Cu < 0.04%	Cu ≤ 5%
Ca	0.003% ≤ Ca ≤ 0.0100%	(total content of Mo, W, Sn, Sb, Mg, Ca, Ce, and Co trace elements) ≤ 0.5%

Applicant first argued that the prior art reference did not disclose a single example composition having the claimed amounts of Al, Cu, and Ca. The PTAB quickly dismissed this argument, noting that the prior art reference was “not limited to its examples.”

Next applicant argued that the prior art reference did not recognize that the amounts of Al, Cu, and Ca were result effective and undue experimentation would have been required to arrive at the claimed narrow ranges. The PTAB replied that the prior art reference would have suggested to a skilled artisan that “all Al, Cu, and total trace element amounts within the disclosed ranges are effective for achieving” the goal of the prior art reference, “a non-oriented magnetic steel sheet whose core loss in a high frequency range can be fully reduced… including amounts within the… [claimed] ranges.”

Applicant then turned to its experimental results. Applicant argued that its experimental results showed that adding Ca in the claimed amounts to a steel sheet containing ultra-low amounts of Al unexpectedly reduces iron loss.

The PTAB noted that applicant’s experimental results were limited to compositions having a Si content of 1.3% and 1.6 % and an Mn content of 0.5%, while the claim encompassed Si contents as high as 4.0% and Mn contents as high as 3.0%. The PTAB then noted a statement in applicant’s specification that Si and Mn have the effect of reducing iron loss (the same effect applicant attributed to addition of Ca in describing its experimental results). In view of this statement, the PTAB concluded that applicant would have to provide evidence that its experimental results were representative of compositions including the minimum claimed amount of Ca and the maximum claimed amounts of Si and Mn, to effectively rebut the examiner’s assertion of obviousness.

Takeaway: Once an examiner has established that a prior art range overlaps with a claimed range, it will be difficult to persuade the examiner (or PTAB) that selection of a subrange would not have been obvious in the absence of evidence of unexpected results – in this case, the PTAB seemed annoyed that applicant even tried. It may be preferable to leave out arguments that will never succeed (e.g., the claimed composition is not exemplified in the prior art reference) and emphasize the results that might succeed (unexpected results).

A composition claim with many components, each with its own range of amounts, can make it difficult to prove that evidence of unexpected results is “commensurate in scope” with the claim. In this case, applicant showed a desirable effect over the entire range of amounts of the component it believed was important (Ca amount), provided a limited number of data points for the other components. It is often not practical to prepare a large number of compositions encompassed by a claim, but this can be addressed with a technical explanation for why additional experiments would not be expected to yield significantly different results (even more helpful if such explanation is provided in a declaration by a skilled artisan).

Judges: Owens, McGee, Inglese

Obviousness rejections of composition claims are often premised on an examiner’s assertion that it would have been obvious to replace a component in a primary reference composition with a functionally equivalent component from a secondary reference. As discussed in a prior blog, the context of a disclosure of functional equivalence is key because obviousness requires an examiner to show a skilled artisan would have had an apparent reason to modify the prior art to arrive at the claimed invention. And when a component is taught to be an alternative for a completely different purpose, this undercuts the apparent reason to modify the prior art. Ex parte Shooshtari is illustrative.

The claims on appeal in Shooshtari were drawn to a binder composition that included “a catalyst for catalyzing a crosslinking reaction between the reducing sugar and the crosslinking agent, wherein the catalyst comprises a sulfonic acid compound.” The primary reference relied on by the Examiner disclosed a binder composition that included a pH adjuster, such as HCl, for preventing unwanted polymerization, but it did not disclose the presence of a sulfonic acid compound.

To remedy this deficiency the Examiner relied on a secondary reference that taught a binder composition containing a mineral acid catalyst, such as HCl or p-toluene sulfonic acid, to effect crosslinking reactions. According to the Examiner, it would have been obvious to replace the HCl pH adjuster of the primary reference with the sulfonic acid polymerization catalyst of the secondary reference. The Board disagreed.

In particular, the Board found that the primary reference taught HCl for the sole purpose of adjusting the pH to inhibit unwanted polymerization, while the secondary reference taught HCl and sulfonic acid as acid catalysts to effect crosslinking reactions–a completely different purpose. Consequently, the Board held the Examiner failed to identify a reason why a skilled artisan would have sought to include the acid catalyst of the secondary reference in the composition of the primary reference.

Takeaway: Shooshtari shows the value in analyzing the purpose of each component of a composition when facing an obviousness rejection that relies on functional equivalence. The purpose and function of the components ties into whether there is an apparent reason to modify the prior art in the manner proposed by the Examiner. Here, the purpose of the components in each of the references was contradictory to the other such that a skilled artisan would not have had a reason to equate and replace them. Accordingly, when facing a rejection that relies on functional equivalence it is important to fully assess the purpose and function of the components involved.

Judges: T. Ownes, W. Wilson, J. Snay

There is no requirement to provide unexpected results until the Patent Office establishes a prima facie case of obviousness. Seems simple, but Ex parte Popplewell shows Examiners still put the cart before the horse and improperly seek evidence of unexpected results.

This initial burden for showing unpatentability falls on the patent office because § 102 mandates that “[a] person shall be entitled to a patent unless.” See In re Glaug, 283 F.3d 1335, 1338 (Fed. Cir. 2002) (the PTO “bears the initial burden of presenting a prima facie case of unpatentability… However, when a prima facie case is made, the burden shifts to the applicant to come forward with evidence and/or argument supporting patentability.”). Despite this unambiguous framework of burden shifting, Examiners routinely seek evidence of unexpected results prematurely.

In Popplewell, the independent claim required a spray dryer in a particular method to have inlet and outlet air humidity values between 0–4 and 10–20 g H₂O/kg dry air, respectively. The Examiner admitted that the prior art relied on did not teach the inlet or outlet air humidity. While this should have been the end of examination, the Examiner took the position that the claimed inlet and outlet air humidities did not provide an unexpected result over the prior art.

On appeal, the Board found the Examiner’s statement regarding the claimed air humidities to be nothing more than a “mere conclusory statement[]” lacking an “articulated reasoning with some rational underpinning to support the legal conclusion of obviousness.” From the Board’s perspective, the Examiner failed to show that the prior art taught or suggested the inlet and outlet air humidities and failed to provide any explanation as to why the claimed humidities would have been obvious. Consequently, the Board held the Examiner’s request for a showing of unexpected results was inappropriate.

Takeaway: Poppelwell is a good reminder that: one, “obviousness requires a suggestion of all limitations in a claim”; and two, an Examiner’s demand for evidence of unexpected results prior to showing a suggestion of all limitations is improper. CFMT, Inc. v. Yieldup Intern. Corp., 349 F.3d 1333, 1342 (Fed. Cir. 2003). It is surprising to see a case like this on appeal because it requires the Examiner and an appeal brief review panel to misunderstand the burden shifting framework before the case is sent to the Board, but it shows why some appeals are inevitable.

Judges: G. Best, L. Ren, M. Cashion

Applicants can traverse rejections by submitting evidence in the form of a declaration under 37 CFR 1.132. While factual evidence, such as additional experimental data, is preferable, opinion testimony, which is often brushed off by examiners, is entitled to consideration as long as the opinion is not on the ultimate legal conclusion. A recent decision of the Patent Trial and Appeal Board (“Board”) – Ex parte Zhu (Appeal 2021-001375) – illustrates a situation where an expert’s opinion testimony provided evidence that successfully traversed the Examiner’s obviousness rejection.

Appellant’s claimed invention in Zhu was directed to an electrochemical test sensor containing a base, a lid, multiple electrodes, and a dried reagent. The dispositive issue before the Board was whether the evidence of record supported the Examiner’s finding that the primary reference (Bateson) described or suggested an electrochemical test sensor having a dried reagent that “has a uniformity in which the ratio of the thinnest point to the thickest point is greater than about 0.2” as claimed.

The Examiner admitted that Bateson did not explicitly disclose the feature but provided a hypothetical calculation based on Bateson’s disclosure, including the drawings, and obtained a ratio of 0.64 between the thinnest and thickest points.

Appellant responded with declaratory evidence from Mr. Brown (an employee of the assignee’s subsidiary company) explaining why the Examiner’s hypothetical calculation was erroneous. Mr. Brown stated that when a dry reagent was obtained from a wet reagent, “[t]he exact percentage of the reduction in the thickness would depend on the drying conditions and the crystalline or molecular structure of the dissolved solid materials in the wet reagent.” Mr. Brown further stated that “details like the contour of the dried reagent” must be considered when the ratio was calculated because the surface of the dried reagent was not smooth, citing a figure in Appellant’s application as a proof and noting that a skilled artisan would expect the dried reagent in Bateson to exhibit the “coffee ring” effect upon drying, which represented a non-uniform reagent surface.

The Examiner gave little or no weight to Mr. Brown’s statements. While noting that Bateson did not disclose the “coffee ring” effect or details pertaining to the surface contour of the wet or dried reagent, the Examiner argued that “it would be improper to read into the disclosure of Bateson to give the surface of the reagent any particular contour without some teaching, suggestion and/or evidence to do so.”

The Board, however, found that Brown’s testimony was valid evidence showing that a skilled artisan would have expected a calculation of the ratio to require details such as the contour of the surface of the reagent. Because, as acknowledged by the Examiner, Bateson did not disclose any noteworthy details regarding the surface contour of the reagent, the Board found that the record before it supported Appellant’s position that the Examiner failed to make a sufficient showing that Bateson disclosed or suggested the recited ratio.

Takeaway: It is known to patent practitioners that arguments of counsel are not evidence and must be supported by an appropriate affidavit or declaration from an expert. The expert can be an outside expert or someone from inside the company as in Zhu as long as they have appropriate expertise. While an opinion affidavit or declaration which states only conclusions may have little probative value, weight and deference should be given to factually supported statements and, particularly, to the underlying factual basis, as illustrated by Zhu.

Judges: M. N. Ankenbrand, B. D. Range, and L. Ren

In Ex parte Abbott (Appeal No. 2021-000770), the examiner rejected the claims as obvious based on an optimization rationale. The PTAB reversed.

Independent claim 1 recited a lighting device for an additive manufacturing machine (i.e., a 3D printer). The device included an array of light sources configured to emit monochromatic light within a band of wavelengths. The band of wavelengths included a peak light absorption of a liquid coalescing agent, so that when the liquid coalescing agent absorbed the light, heat would be generated to melt or sinter a patterned building material.

Claim 1 recited a spectral intensity of at least 1 x 10¹² W m^-3 sr^-1 for each of the monochromatic light sources. The dispositive issue on appeal was whether this limitation was suggested by the applied references.

The examiner acknowledged that the primary reference (Miller) did not disclose this limitation. However, the examiner cited Miller’s teaching that the “amount of radiation provided to each location on the built model should be the amount that ensures sufficient curing in that location,” and that “[t]he radiation may be of any type, or in any wavelength that causes curing of the build material.” The examiner found that a skilled artisan “would have recognized that the light sources taught by Miller could be operated to emit a desired spectral intensity.” The examiner concluded that the claimed spectral intensity could be obtained through “routine optimization of this result-effective variable to provide the intended result of curing of build material during an additive manufacturing process.”

In contrast, the applicant noted that the Miller reference taught no specific values or ranges for spectral intensity. Because of this, the applicant argued that an optimization rationale was unsupported. The applicant cautioned that if the examiner’s position were correct, then the general disclosure of Miller would be sufficient to “render obvious the use of radiation to solidify anything under any conditions for every 3D printing process no matter how specific and how novel the radiation and no matter how different the process.”

The PTAB agreed with the applicant. The PTAB found the lack of any disclosed range of spectral intensity in Miller to be “akin to a very broad range (as there is not a set limit since no limit is provided in Miller).” The PTAB found such a broad range to be “so broad that there is no invitation for routine optimization.” Accordingly, the PTAB reversed the obviousness rejection.

Takeaway: Whenever an examiner takes the position that a claimed variable is a result-effective variable that would have been obvious to optimize, it is important to carefully evaluate the teaching of the prior art relating to the claimed variable. If, as in Ex parte Abbott, there are no specific values or ranges of the claimed variable in the prior art, then the optimization rationale might lack adequate support.

Judges: Franklin, Praiss, Inglese

Even a casual, unscientific survey of recent PTAB decisions shows a clear and unmistakable trend: shorter decisions, with little or no discussion of issues not specifically raised by Appellant. While those seeking review of an Examiner’s decision could, at one time, expect both an independent review of the underlying rejection as well as consideration of their arguments, the PTAB is now more likely to focus solely on, and respond only to, those issues raised in Appellant’s brief. Indeed, 20% of recent decisions in Tech Centers 1600 and 1700 included the following language:

We review the appealed rejections for error based upon the issues Appellant identifies, and in light of the arguments and evidence produced thereon. Ex parte Frye, 94 USPQ2d 1072, 1075 (BPAI 2010) (precedential), cited with approval in In re Jung, 637 F.3d 1356, 1365 (Fed. Cir. 2011) (“[I]t has long been the Board’s practice to require an applicant to identify the alleged error in the examiner’s rejections.”).

Whether this trend is due to an increased workload at the PTAB, represents an attempt to reduce pendency, or is caused by something else altogether doesn’t really matter. What matters is that Appellants recognize this new reality and respond to it.

Unfortunately, this means that Appeal Briefs may need to include secondary arguments that, at one time, might have been left out as being distracting. More importantly, however, it is imperative to include, wherever possible, those arguments that appear to be “in favor” at the PTAB (i.e., those arguments that appear regularly in cases where the Examiner is reversed), and to present them prominently.

Right now, the “in favor” argument for Appellants unquestionably is whether the prior art provides a reasonable expectation of success. We have written extensively about this in our blog (link, link, link, link, link), saw it at the end of last year at the Federal Circuit in Teva Pharm. U.S. v. Corcept Therapeutics, Inc., 2021-1360 (Fed. Cir. Dec. 7, 2021) (invalidating the claim requires proof of “a reasonable expectation of success in achieving the specific invention claimed”), and may soon see it addressed at the Supreme Court in Apotex Inc. v. Cephalon, Inc., where infringer Apotex, in their Writ of Certiorari, neatly summed up the doctrine’s current pro-applicant, pro-patentee, pro-validity understanding that an obvious-to-try approach is only sufficient to invalidate where there is a reasonable expectation of success:

[T]he Federal Circuit seems to believe that if there is any uncertainty about whether an obvious-to-try approach will succeed, that potentially compromises the motivation to try an obvious solution to a pressing problem, and therefore produces patent monopolies for what is obvious to try. Indeed, so ingrained has the motive-to-try-what-is-likely-to-succeed test now become in the Federal Circuit’s obviousness psyche, that the Federal Circuit now sometimes includes motivation as a fifth Graham factor.

Because a “no reasonable expectation of success” argument cuts against the establishment of a prima facie case, success on this issue does away with any need for a showing of unexpected results, which can sometimes be difficult to provide. Thus, until there is something to the contrary diminishing this doctrine’s current status, understanding, and application, best practice issue advocacy dictates that whenever a “no reasonable expectation of success” argument can be made, it should be made. Supporting such a position during prosecution with a Declaration makes ignoring it, and refuting it, very difficult for both the Examiner and the PTAB.

A typical Markush group is structured as “selected from the group consisting of A, B, and C.” The language is closed in nature due to the closed transitional phrase “consisting of.” However, it is not uncommon for an open-ended claim to recite a Markush group in patents or patent applications related to chemical arts. An issue that often arises , therefore, is whether unrecited members of the “closed” Markush group are allowed in open-ended claims. In Ex parte Kapitan (Appeal 2021-001272), the Patent Trial and Appeal Board (“Board”) addressed such an issue.

Appellant’s claimed invention in Kapitan was directed to a process for making a methylfluoroacrylate “comprising” steps A-D, wherein “the solvent in at least steps C and D … is an alkane selected from a group consisting of pentane and hexane.”

The Examiner rejected the claimed process as obvious over a combination of several prior art references. The Examiner admitted that the primary reference did not disclose using pentane or hexane as the solvent in making methylfluoroacrylate; and relied on a secondary reference, Sedlak ‘967, for the admitted deficiency. In particular, the Examiner found Sedlak ‘967 used inert solvent, including petroleum ether, which, according to the Examiner, “consists of pentane and hexane hydrocarbons.” However, as noted by the Board, the Examiner did not provide evidence establishing that petroleum ether was either pentane or hexane.

Appellant, on the other hand, provided several prior art references during prosecution showing that petroleum ether was not a single composition but a mixture of aliphatic hydrocarbons, such as a mixture of C₅ to C₁₃ paraffins that might contain a small amount of aromatic hydrocarbons.

The Board thus agreed with Appellant that petroleum ether had numerous variations of petroleum ether components that were not limited to pentane or hexane. The Board noted that by using the open-ended transitional phrase “comprising,” the claimed process allowed for additional steps. However, the Board further noted “that additional steps may be allowed does not mean that the solvent for use in the reaction step C as modified by the wherein clause, i.e., the alkane solvent [] being ‘selected from a group consisting of pentane and hexane,’ can be something other than pentane or hexane.” Citing Amgen, Inc. v. Amneal Pharms. LLC, 945 F.3d 1368, 1377–78 (Fed. Cir. 2020), which discussed in detail Multilayer Stretch Cling Film Holdings, Inc. v. Berry Plastics Corp., 831 F.3d 1350 (Fed. Cir. 2016), the Board concluded that, just as was the case in Multilayer, the suitable solvent required to be used in step C in Appellant’s claimed process was restricted to the listed solvents by the use of the closed Markush transition phrase “selected from the group consisting of.”

Because Sedlak ‘967’s teaching of using “petroleum ether” in its reaction scheme as an inert solvent did not indicate that pentane or hexane alone was a suitable inert solvent, the Examiner’s application of the prior art references was not sustainable.

Takeaway: Kapitan, like Multilayer, illustrates that without other language altering the meaning of a Markush clause, other unrecited members or mixtures of the recited members are not allowed even in an open-ended claim. Amgen illustrates a different situation. Specifically, the Amgen Court held that additional unrecited members of a Markush group and mixtures of the recited members were allowed if the Markush clause included qualifying language such as “at least one” as in “at least one selected from the group consisting of A, B, and C” and was preceded by an open-ended transitional phrase such as “comprising.” Indeed, the result would have been different if Appellant in Kapitan had recited “the solvent in at least steps C and D … comprises an alkane selected from the group consisting of pentane and hexane.”

Judges: D. E. Adams, T. Chang, and R. H. Townsend

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Functional Equivalence Requires Similar Purpose

PTAB Finds Examiner’s Request for Unexpected Results Inappropriate

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Are Unrecited Members Allowed in Open-ended Claims Reciting Markush Groups?

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