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May 28, 2021by Matthew Barnet1

U.S. patent examiners often use an optimization rationale when rejecting claims as obvious. Such situations typically arise when a claim recites a range of possible values for a certain variable, and the prior art discloses a value of the variable that is outside the claimed range. In these situations, examiners usually take the position that the claimed range would have been obvious to obtain by routine optimization of a “result-effective variable,” i.e., a variable that achieves a recognized result in the prior art.

In other situations, however, examiners apply a result-effective variable rationale to a claimed property that is not disclosed in the applied prior art. This is illustrated in the recent Patent Trial and Appeal Board (“Board”) case of Ex parte Horiuchi (Appeal No. 2020-000126).

In Horiuchi, independent claim 1 recited:

A covering material for an electric wire, the covering material having a composition containing a polyvinyl chloride,

wherein the composition of the covering material comprises a characteristic such that a change curve of a loss modulus with respect to temperature for the composition of the covering material containing the polyvinyl chloride has no peak within a temperature range of -30°C to 60°C, which is a temperature range in a usage environment for the electric wire, and

wherein the composition of the covering material comprises more than or equal to 35 parts by weight and less than or equal to 50 parts by weight of a plasticizer and 2 to 20 parts by weight of a flexible resin with a melt flow rate of 1.0 g/10 min or less, the plasticizer and the flexible resin combined with respect to 100 parts by weight of the polyvinyl chloride such that the composition comprises the characteristic.

The examiner rejected claim 1 as obvious. The examiner acknowledged that the applied prior art did not disclose the claimed property of a change curve of loss modulus having no peak within a temperature range of -30°C to 60°C. However, the examiner took the position that the

change curve of loss modulus with respect to temperature is a result effective variable. As the change curve of loss modulus with respect to temperature peaks the material undergoes a decrease in flexibility. Thus, it would have been obvious to…have a covering material that has a change curve of loss modulus with respect to temperature which shows no peak within a temperature range in a usage environment for the electric wire motivated by the expectation of maintaining flexibility over the usage environment for the electric wire, since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art.

In response, the applicant argued that the claimed property of having no peak within a certain temperature range of the change curve of loss modulus was not itself a result-effective variable known in the prior art. Instead, the applicant explained that this claimed property depended on at least five other variables: the amount of plasticizer, the amount of flexible resin, the melt flow rate of the flexible resin, the relative proportions of components, and temperature. The applicant argued that a skilled artisan would understand that “such a complex combination of material concentrations along with melt flow rates could not be summarily characterized as one ‘variable’ in the form of a simple graph of loss modulus v. temperature, that could be routinely manipulated.” Thus, the applicant argued that it would not have been obvious to achieve the claimed property from the applied prior art.

The Board agreed with the applicant, and reversed the obviousness rejection. The Board did not explain its reasoning regarding the examiner’s result-effective variable rationale, other than mentioning that it adopted the reasoning provided by the applicant. However, the Board emphasized that the amount of plasticizer in the claims (35 to 50 parts by weight with respect to 100 parts PVC) was higher than the upper limit in the applied prior art (30 parts by weight with respect to 100 parts PVC). The Board noted that the applied prior art taught away from using an amount of plasticizer higher than 30 parts by weight, since doing so could cause the covering material to have an insufficient damage-resistance property. The Board concluded that “the Examiner does not explain adequately how one skilled in the art would arrive at the claimed covering material from the [applied prior art].”

Takeaway: Whenever an examiner takes the position that a claimed property is a result-effective variable that would have been obvious to optimize, it is important to carefully evaluate the teachings of the prior art relating to the claimed property. If, as in Ex parte Horiuchi, the claimed property is distinguishable from variables in the prior art, then this distinction can help overcome an examiner’s obviousness rejection. If the claimed property is related to certain claimed variables (such as concentration of a component), but the claimed values of these variables do not overlap the corresponding values in the prior art, this approach can be particularly useful.

Judges: Smith, Cashion Jr., Inglese


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April 30, 2021by Beau Burton

Ratios can be useful when claiming a subset of two well-known components or variables, particularly when the subset (defined by a ratio) provides a new and useful result. However, when the prior art teaches broad ranges for the individual components or variables, it is common for examiners and petitioners to argue obviousness based on overlapping theoretical ranges of the ratio derived from selecting the maximum and/or minimum values for each of the components or variables. The issue with this is approach is that the prior art may not direct a person of ordinary skill in the art  (POSA) to the particular selections required to arrive at the claimed ratio. SNF S.A. v. Solenis Technologies is illustrative. IPR2020-01730, Paper 10 at 4 (PTAB April 22, 2021).

In SNF S.A., the challenged claims required a glyoxalated copolymer (G-PAM) obtained by reacting:

[A] 5–40 parts of glyoxal; and

[B] 60–95 parts of a cationic copolymer including:

[b1] ~15–85 wt% of diallyldimethylammonium halide monomer (DADMAC); and

[b2] ~85–15 wt% of acrylamide monomer,

the cationic copolymer having a weight average molecular weight (WAMW) of 120,000 to 1,000,000 Daltons, and

a ratio of the WAMW to the weight % of the DADMAC being greater than 4000 Daltons/weight%.

According to the background of the patent, the patentee found that the ranges of the WAMW and % DADMAC in combination with the claimed ratio thereof improved water drainage during processing and increased the strength of paper or boards treated with the G-PAM.

The petitioner, SNF S.A., argued obviousness based on three different primary references: Wright, Lu, and Dauplaise. The petitioner admitted that none of the cited references disclosed a ratio between WAMW and % DADMAC. To remedy this deficiency, the petitioner presented two arguments.

The petitioner’s first argument was that a POSA would have selected values of the WAMW and % DADMAC disclosed by each of the references to arrive at the ratio required by the claims. Specifically, with respect to the Wright reference, the petitioner argued “the ratio of 150,000 WAMW to 25 wt.% DADMAC, as both taught by Wright ’343, is 6,000 [and] … the ratio of 1,000,000 WAMW to 30 wt.% DADMAC is 33,333.” The petitioner supported this assertion with an expert declaration that similarly stated it would have been “obvious” and “routine” to select molecular weights of 150,000 (an upper endpoint of the preferred range) and to select DADMAC concentrations of 25% and 30% (preferred concentrations).

For ease of discussion, the scope covered by the claims (shaded blue box) relative to the scope disclosed by the Wright reference (shaded red box) and the two particular data points of the Wright reference relied on by the petitioner (red dots) are shown graphically below and here:

As shown above, Wright’s broad WAMW range of 30,000 to 5,000,000 and broad % DADMAC range of 0.1–90 wt% cover a WAMW/%DADMAC ratio of 4,000, as they theoretically cover ratios from 333 to 5×107. And although one of the ratios derived by the petitioner (lower red dot) was derived from a preferred amount of DADMAC (25 wt%) and an upper endpoint of a preferred WAMW range (150,000), the Board found:

Petitioner, however, never explains how or why a person of ordinary skill in the art would have been led to select the value ‘150,000 WAMW,’ or ‘25 wt.% DADMAC,’ or any of the specific values it uses to calculate the claimed ratio. Nor does Petitioner direct us to any disclosure in the prior art showing an embodiment having the specific values used in Petitioner’s calculations.

Absent explanation from Petitioner, it appears that Petitioner picked the specific values it used to calculate a ratio from broad, unrelated ranges of WAMW and % DADMAC disclosed in the prior art simply because they combine to produce a ratio that meets the ratio recited in the claims of the ’320 patent. This suggests Petitioner relied on hindsight in forming its challenges. Metalcraft of Mayville, Inc. v. The Toro Co., 848 F.3d 1358, 1367 (Fed. Cir. 2017) (‘[W]e cannot allow hindsight bias to be the thread that stitches together prior art patches into something that is the claimed invention.’).

This use of hindsight is not excused by the mere fact that the specific values combined to produce the claimed ratio fall within the ranges disclosed in the prior art.

The other two primary references relied on by the petitioner, Lu, and Dauplaise, suffered similar defects.

The petitioner’s second argument was that “a POSA would have arrived at the ratio using routine experimentation to optimize result-effective variables, as guided by the art.” The Board also rejected this argument.

First, the Board found that a POSA would not have optimized the ratio itself because “there is no evidence that skilled artisans knew that the claimed ratio of WAMW to % DADMAC was a parameter of any importance or one worth optimizing.” That is, the ratio was not a result-effective variable.

Second, the Board found that there was no persuasive evidence to support a conclusion that independently optimizing WAMW and % DADMAC would result in a polymer having the claimed ratio rather than one of the many ratios falling outside the scope of the claims. Again, the Board emphasized the innumerable combinations of values. But it seemed that the Board was more persuaded by the fact that there was evidence of polymers outside the scope of the claim exhibiting the same properties as those having the claimed ratio such that optimization could equally result in a copolymer having a ratio outside the claim. Ultimately, the Board concluded that the evidence did not support the petitioner’s assertion that independent optimization would lead to the claimed ratio.

For the foregoing reasons, the Board concluded that the petitioner failed to carry its burden and declined to institute the IPR.

Takeaway: When facing an office action or post-grant petition in which a claimed ratio is alleged to be obvious based on the selection or optimization of the components making up the numerator and denominator, you should first determine whether the ratio itself is a result-effective variable. If not, the next step is to determine whether there is an embodiment that discloses values for the numerator and denominator that would result in the claimed ratio. As shown in SNF S.A., the fact that specific values can be combined to produce the claimed ratio is insufficient by itself when there are innumerable combinations of values. If neither of these applies, the final step is to determine whether the prior art teaches a reason to optimize the numerator and denominator in a manner that would result in the claimed ratio.

Judges: C. Crumbley, J. Abraham, D. Cotta


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February 19, 2021by Yanhong Hu

In Ex parte Gomez (Appeal 2020-001462), the Patent Trial and Appeal Board (“Board”) considered an Examiner’s obviousness rejection based on an allegedly overlapping range and, alternatively, optimization of a result-effective variable.  The Board found neither of the Examiner’s two rationales were persuasive.

The sole independent claim 19 illustrated the claimed subject matter on appeal and was drawn to a method of improving the scratch resistance of a glass.  The claimed method included, among other steps, a step of “forming a porous silica-rich layer on the surface of the glass, wherein the silica-rich layer extends from the surface to a depth of greater than or equal to 100 nm to less than or equal to 600 nm into the glass.”

The Examiner rejected claim 19 as obvious over Amin.  The Examiner found Amin disclosed the formation of a porous silica-rich layer on a surface of a glass by treating the surface with an acid to improve the scratch resistance of the glass.  The Examiner noted Amin disclosed the preferred depth of the silica-rich layer was less than 50 nm, which was outside the claimed depth range.  However, the Examiner contended the claimed depth of the silica-rich layer would still have been obvious over Amin under two rationales.

First, the Examiner noted Amin disclosed that the surface of the glass had a root mean square (RMS) roughness of 50-5000 nm.  While acknowledging “RMS roughness is not directly equivalent to the depth,” the Examiner believed “given that it is the root mean square of the peak-to-valley heights (i.e. root mean square of the depth across the surface) it is apparent that a RMS roughness of 50–5000 nm overlaps [the recited depth range].”

Second, the Examiner found the depth of the silica-rich layer was a result-effective variable because Amin disclosed that the silica-rich layer was selected “based on the desired balancing between the improved adhesion of the subsequent layer and a depth whereby the mechanical properties are not affected.”  The Examiner then concluded it would have been obvious to optimize the depth and arrive at the claimed range “to obtain the desired chemical and mechanical properties.”

The Board found Amin’s disclosure of the RMS roughness of 50-5000 nm was related to an alternative embodiment of Amin’s invention that involved forming a glass article having a textured or patterned surface disposed between a chemically strengthened layer and an exterior amphiphobic layer.  The Board pointed out the Examiner did not provide technical reasoning supported by objective evidence to prove that RMS roughness corresponded to, or was equivalent to, the depth of a silica-rich layer into a glass.  Because the Examiner’s allegedly overlapping range disclosed in Amin appeared to relate to a variable irrelevant to the claimed depth of silica-rich layer, the Board concluded the Examiner’s assertion of overlap appeared to be based on speculation, which did not constitute a sufficient basis for establishing prima facie obviousness.

In addressing the Examiner’s allegation of optimization of a result-effective variable, the Board found that Amin described conducting an acid treatment to remove chemically exchanged (potassium) ions from the surface of a glass to a depth typically of ≤ 50 nm, “whereby the mechanical performance of the chemically strengthened glass (for example, strength, scratch resistance, impact damage resistance) is not affected.”  Amin further disclosed the depth was preferably 5-15 nm and described a specific example in which the depth was only 10 nm. The Board noted these disclosed depth values were “all far below” the recited depth range and concluded “[one] of ordinary skill in the art would have understood this disclosure to implicitly indicate that removing chemically exchanged ions to a depth greater than 50 nm may adversely affect the mechanical performance of the glass.”  The Board did not find the Examiner provided sound technical reasoning supported by objective evidence to establish that a skilled artisan would have disregarded Amin’s explicit disclosure of a typical depth of ≤ 50 nm and implicit disclosure that removing ions to a greater depth might adversely affect the mechanical performance of the glass.

Citing In re Sebek, the Board emphasized that “[when] the prior art disclosure suggests the outer limits of the range of suitable values, and that the optimum resides within that range, and where there are indications elsewhere that in fact the optimum should be sought within that range, the determination of optimum values outside that range may not be obvious.”  In Gomez, the claimed depth range was outside an optimum range of ≤ 50 nm disclosed in Amin and Amin taught in multiple places that the depth should be within the optimum range.  In other words, Amin appeared to teach away from the claimed depth range.  Therefore, the Board also rejected the Examiner’s optimization rationale.

Because the Examiner did not provide a sufficient factual basis to support his conclusion that the claimed depth of the silica-rich layer would have been obvious over Amin, the Board reversed the rejection.

Takeaway:  Claiming a range is particularly common in chemical arts.  If a claimed range does not overlap a prior art range, examiners will sometimes argue the parameter of the range is a result-effective variable that could be optimized to reach the claimed range.  As illustrated by Gomez (see also Nonobviousness: PTAB Rejects Examiner’s Optimization by Routine Experimentation Rationale), even if the parameter passes the muster to be a result-effective variable, the optimization rationale will not stand if the prior art implicitly teaches away from the claimed range by disclosing a non-overlapping optimum range and encouraging one to seek a value within the optimum range.

Judges:  R. H. Delmendo, M. P. Colaianni, and J. E. Inglese


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January 19, 2021by Beau Burton

Claimed ranges are prima facie obvious when they overlap a prior art range. When there is no overlap, Examiners will bridge the gap by arguing that the parameter of the range is a result effective variable (such that it would have been obvious to go beyond the literal range) or rely on Titanium Metals to assert that the claimed range is obvious simply because it is “close enough” to the prior art range. The Examiner in In re Yanez tried both of these approaches but failed. Appeal No. 2020-001246 (PTAB Dec. 10, 2020) (non-precedential).

The claim at issue in Yanez required a nickel-aluminide alloy comprising, among other things, 0.15 wt % or less zirconium (Zr). The prior art, Liu, disclosed a nickel aluminide composition that included “from about 0.1 to about 1.5[atomic]% zirconium.” The Examiner converted the lower endpoint of 0.1 at.% in Liu to 0.17 wt%.

The Examiner recognized that Liu’s lower endpoint of 0.17 wt% exceeded the Applicant’s upper limit of 0.15 wt%. However, the Examiner argued: (1) “0.17 wt% is considered close to presently claimed 0.15% or less according to MPEP 2144.05 I”; and (2) “Liu expressly disclose[s] varying amounts of Zr … leads to different YS [(yield strength)] and elongation as illustrated in Figure 2a and 2b … [I]t would have been obvious to one skilled in the art to have adjusted the result-effective variable of Zr amount, in the Nickel-aluminide alloy of Liu in order to achieve a desired VS [sic, YS] and elongation.”

The Board rejected the Examiner’s “close enough” position, stating “no evidence that Liu’s about 0.17 wt% Zr is sufficiently close to the Appellant’s 0.15 wt% Zr to have suggested 0.15 wt% Zr to one of ordinary skill in the art.”

Next, the Board found “[t]he result effective variable in Liu’s Figures 2a and 2b is [molybdenum] Mo concentration, not [zirconium] Zr concentration.” The Board further noted that an example in Liu having 0.3 at% of Zr had a yield strength between examples containing 0.5 at% and 1.0 at% of Zr; suggesting the Zr content did not correlate with yield strength.

Absent a factual basis to support the Examiner’s positions, the Board reversed the obviousness rejection.

Takeaways: When facing an obviousness rejection where there is a nonoverlapping range, it is important to assess how the prior art range is arranged relative to the claimed range and what the prior art teaches about the range.

The “close enough” rationale from Titanium Metals made sense in that case because the prior art disclosed two compositions (no ranges were described) and the claimed composition fell between those two compositions. Thus, while there was no overlap with the specific compositions in Titanium Metals, a skilled artisan would have expected that an intermediate composition would have the same properties.

The rationale from Titanium Metals starts to break down when the nonoverlapping claimed range is next to the prior art range and the prior art does not teach that the range is flexible (i.e., does not use the modifiers “about” or “approximate”) or suggest that the properties outside the disclosed range would be expected to be the same (i.e., does not state that any concentration is acceptable before setting forth preferred ranges). See In re Patel, 566 F. App’x 1005 (Fed. Cir. 2014) (nonprecedential) (rejecting the PTO’s position that proximity of nonoverlapping ranges alone is sufficient to establish a prima facie case of obviousness). In Yanez, while the prior art used the modifier “about,” it appears that the Board concluded a skilled artisan would not have expected the claimed composition to have the same properties since the concentration of Zr did not correlate with the yield strength (i.e., the lowest concentration of Zr had an intermediate yield strength).

Yanez also shows the importance of assessing the prior art teachings surrounding the alleged result-effective variable. Here, the data relied on by the Examiner showed that the result effective variable was a completely different element than asserted by the Examiner. As such, there was no basis for the Examiner’s rejection. For another good illustration on this topic, readers are referred to Matthew Barnet’s recent blog, “Nonobviousness: When a Result-Effective Variable Is Different from the Claimed Variable.”

Judges: T. Owens, B. Baumeister (concurring), B. Range


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January 8, 2021by Matthew Barnet1

U.S. patent examiners often use an optimization rationale when rejecting claims as obvious. Such situations typically arise when a claim recites a range of possible values for a certain variable, and the prior art discloses a value of the variable that is outside the claimed range. In these situations, examiners usually take the position that the claimed range would have been obvious to obtain by routine optimization of a “result-effective variable,” i.e., a variable that achieves a recognized result in the prior art.

However, in such a rejection, it is important that the claimed variable matches the result-effective variable from the prior art. This issue is illustrated in the recent Patent Trial and Appeal Board (“Board”) case of Ex parte Amini (Appeal No. 2020-000285).

Claim 1 recited (in part):

An article comprising:

a MAX phase solid in the form of particles, the MAX phase solid having a formula Mn+1AXn, where n=1-3, M is an early transition metal, A is an A-group element, and X includes at least one of carbon and nitrogen; and

a high temperature melting point metallic material through which the particles of the MAX phase solid are dispersed such that the particles are spaced apart and the metallic material surrounds the particles…wherein the high temperature melting point metallic material and the MAX phase solid together define a porosity of 50 vol% to 80 vol%.

The MAX phase solid particles could be, for example, Ti2AlC or Ti3SiC2, and the high temperature melting point metallic material could be Ti, Zr, Y, Sc, Be, Co, Fe, Ni, or an alloy thereof. The inventors found that the composite material, formed from the MAX phase solid particles dispersed in the metallic material, was well suited for damping applications in high temperature environments, for example as a component of a gas turbine engine.

The examiner rejected claim 1 as obvious over a combination of two references. The examiner relied on the primary reference (“Barsoum”) for a composite material comprising MAX phase particles dispersed in a metallic material. The examiner acknowledged that Barsoum did not disclose a porosity of 50 vol% to 80 vol% as recited in claim 1, and relied on the secondary reference (“Sun”) for this limitation.

In particular, the examiner relied on a description in Sun of a MAX phase having a porosity of approximately 43 vol%. The examiner took the position that this value was close enough to the numerical range of 50 to 80 vol% recited in claim 1 to render this limitation obvious. Alternatively, the examiner took the position that Sun established the porosity to be a result-effective variable that would have been obvious to optimize to obtain the claimed range.

The Board disagreed with the examiner. The Board noted that Sun described the porosity only for the MAX phase solid. In contrast, claim 1 recited the porosity for the MAX phase solid together with the metallic material, i.e., the porosity of the composite material formed by dispersing the MAX phase solid particles in the metallic material. Based on this, the Board found that the numerical value of approximately 43 vol% for the porosity in Sun could not be directly compared to the range of 50 to 80 vol% in claim 1, because these porosities were different variables.

Since these porosities were different variables, the Board also disagreed with the examiner’s rationale relating to a result-effective variable. The Board noted that “[i]t is well established that optimization of a prior art range flows from the normal desire of scientists or artisans to improve upon what is already generally known. But it is equally well established that when the parameter optimized was not recognized to be a result-effective variable, optimization would not have been obvious.” The Board found that the examiner had “not identified evidence in the present record that the prior art recognized the need for the porosity of the composite (‘the high temperature melting point metallic material and the MAX phase solid together’) to be between 50 vol% to 80 vol% as required by independent claim 1.” The Board concluded that “[b]ecause the disclosed porosity of Sun is different than the claimed porosity, there is no basis to conclude that the claimed porosity is a result-effective variable.” Accordingly, the Board 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 teachings of the prior art relating to the claimed variable. If, as in Ex parte Amini, the claimed variable is distinguishable from the variable in the prior art, then this distinction can help overcome an examiner’s obviousness rejection.

Judges: Smith, Dennett, Cashion Jr.


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September 10, 2020by Christopher Bayne

When considering the obviousness of ranges, it is a fundamental principle of U.S. patent law that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” In re Aller, 220 F.2d 454, 456 (CCPA 1955).  Consequently, modifications to readily optimized parameters such as temperatures and concentrations disclosed in the prior art will generally not be patentable under Section 103.  Aller, 220 F.2d at 456.  Furthermore, a presumption of obviousness exists when ranges disclosed in the prior art overlap with the ranges of a claimed invention.  Seee.g.E.I. du Pont de Nemours & Company v. Synvina C.V., 904 F.3d 996, 1006 (Fed. Cir. 2018).