obviousness Archives - ElementIP Law

In the recent decision Laboratory Corporation of America Holdings v. Ravgen, Inc., No. 2023-1342, 2023-1345 (Fed. Cir. Jan. 6, 2025) the Federal Circuit addressed an issue that commonly arises when challenging an Examiner’s determination of obviousness: is there sufficient motivation to combine the references? 

In Ravgen the Board found themselves having to deal with references that were “neither fish nor fowl” in terms of their motivating factors; that is, references lacking clear, easily identifiable and direct statements that either encourage or discourage their combination. In affirming the Board, the Federal Circuit found that the Board had properly weighed the evidence both for and against motivation to combine and correctly found that patentee’s reasoning and evidence against combinability outweighed petitioner’s arguments in favor of combinability.

Critical to this finding was the court’s approval of the Board’s determination, made in view of the noted absence of clearly motivating statements in the references, that “the literature would have dissuaded a [person of ordinary skill in the art] from using formaldehyde or paraformaldehyde in the [Chiu] modified method.” In supporting this decision the Federal Circuit cited Arctic Cat Inc. v. Bombardier Recreational Products Inc., 876 F.3d 1350 (Fed. Cir. 2017) and noted that “[e]ven if evidence does not ‘rise to the level of teaching away,’ it is still proper for the Board to consider evidence that “suggests reasons that a skilled artisan would be discouraged from pursuing such a combination.”

Both Ravgen and Arctic Cat remind us that, in attacking an Examiner’s combination of references, the “gold standard” of a clear teaching away in one or more of the references is not always necessary, and anything in a reference that discourages its combination with another can be used to attack the Examiner’s motivation to combine.

“If you give me six lines written by the hand of the most honest of men, I will find something in them which will hang him.”

― Cardinal Richelieu (1585-1642)

On April 29, 2024, the Patent Trial and Appeal Board in Ex parte Wang (Appeal 2023-003255) affirmed an examiner’s single reference obviousness rejection of a claim to a process for stabilizing a protein against thermal inactivation:

A process for stabilizing a protein against thermal inactivation, comprising: binding a protein to the surface of a solid substrate; the protein bound to the surface by a linker moiety between an active group of the protein and said substrate, wherein the linker comprises a bond formed from one or more active groups selected from the group consisting of alcohol, thiol, carboxylic acid, anhydride, epoxy, and ester, and wherein said bond of the protein to the solid substrate stabilizes the protein against thermal inactivation.

This claim was finally rejected over Minier, characterized by the Examiner as disclosing a protein bound to a solid surface via “an alcohol linker active group bound to [a] metal substrate through a glutaraldehyde active group,” and thereby being inherently stabilized against thermal inactivation.

Appellants made two arguments. First, Appellants argued that surface bonding through a glutaraldehyde group was not included in or suggestive of the requirements of Claim 1. Second, they challenged the inherency finding.

With regard to the first argument, Appellants, in their Pre-Appeal Brief filed in direct response to the final rejection, characterized Claim 1 as reciting “[a] protein bound to the surface [of a solid substrate] by a linker moiety between an active group of the protein and said substrate, wherein the linker comprises a bond formed from [an] alcohol, thiol, carboxylic acid, anhydride, epoxy, and ester.” Then, in their Appeal Brief, Appellants characterized Claim 1 as reciting “[a] process for stabilizing a protein against thermal inactivation comprising binding a protein to the surface of a substrate; … by a linker moiety …. formed from one or more active groups selected from the group consisting of alcohol, thiol, carboxylic acid, anhydride, epoxy, and ester.” In both instances, Appellant argued that the reference’s use of a glutaraldehyde active group failed to disclose bonding a protein to a surface using one of their claimed linker moiety’s active groups. As for their second argument – inherent stabilization – Appellants argued that the reference nowhere discussed or recognized any thermal stabilization of the bound protein.

The Board was having none of it. Characterizing both issues as ones that “resolve based on a proper interpretation of claim 1” the Board walked Appellants through their surface/linker/active group claim language, demonstrating that in Claim 1 the linker’s active group need not be directly bound to the surface in the claim, just located “between” the protein and the surface. And with regard to thermal stability, the Board pointed to Appellants’ specification, which described thermal stability as a property necessarily flowing from the bond. Rejection Affirmed.

What went wrong? Well, Appellant was apprised of the Office’s interpretation of their claim language after the first rejection. Rather than discuss the case with the Examiner and come to agreement as to how to distinguish their clearly different invention from the applied art they barreled ahead with the same claim language, insisting that the Office see things their way. And when the Office didn’t, rather than seek reconsideration from the Examiner, Appellant filed a multi-issue Pre-Appeal Brief that simply upheld the rejection and provided no useful feedback. Full Appeal (with Oral Hearing) followed, after which the Board provided Appellant with the same answer the Examiner had given them two and a half years earlier: your invention is different, but your claims encompass the prior art.

The moral of the story? Differences aren’t important unless they are reflected in the claims. Listen to what the Examiner is saying – they look at the claims differently than you do. Sometimes, they are right. Oftentimes, simple amendments can address the issue, as here.

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.

Recently we reviewed the USPTO’s published Examiner guidance concerning “the flexible approach to determining obviousness that is required by KSR Int’l Co. v. Teleflex Inc. (KSR)” in which the Office instructed Examiners to avoid any type of formalistic or formulaic approach when providing a reason to modify the prior art in favor of relying on any possible source that “may, either implicitly or explicitly, provide reasons to combine or modify the prior art to determine that a claimed invention would have been obvious.” Unfortunately for applicants, this advice seems to have accurately captured the current sensibility of the Federal Circuit which, in Janssen Pharms., Inc. v. Teva Pharms. USA, Inc., No. 2022-1258 (Fed. Cir. Apr. 1, 2024), recently openly admonished a District Court for using a “degree of rigidity” in its obviousness analysis that was foreclosed by KSR and, perhaps most devastatingly, for “ask[ing] the wrong questions about important aspects of the obviousness inquiry.”

In particular, and among the district court’s several identified errors, the Federal Circuit in Janssen found that the district court analyzed the prior art without giving the needed weight to the perspective of a person of ordinary skill in the art (POSA) who is “capable of deducing what references fairly suggest or employing ordinary creativity.” And instead of considering the prior art in context or in combination, the Federal Circuit criticized the district court’s consideration of each reference one-by-one, “identifying each difference or dissimilarity between an individual reference and the claims, but not fully assessing the teachings in toto” thereby yielding a “siloed and inflexible approach” that left insufficient room for consideration of how background knowledge in the art would have impacted a POSA’s understanding of, or motivation to modify, the primary references at issue.” This approach, in the view of the Federal Circuit, inflated the significance of “minor variations between the prior art and the claims,” leading to the district court’s erroneous conclusion of nonobviousness.

Given the general decorum typically surrounding court opinions, this level of direct and unfettered criticism can mean only one thing – that at least for the foreseeable future the USPTO guidelines got it right insofar as the Federal Circuit is concerned. As the Federal Circuit, citing KSR, emphasized in this case, “[a]ssessing obviousness is based on an ‘expansive and flexible approach’ that ‘need not seek out precise teachings directed to the specific subject matter of the challenged claim, for a court can take account of the inferences and creative steps that a person of ordinary skill in the art would employ’.” Applicant beware.

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

On February 27, 2024, the USPTO published “updated guidance to provide a review of the flexible approach to determining obviousness that is required by KSR Int’l Co. v. Teleflex Inc. (KSR).” While these guidelines are “a matter of internal Office management” and do not constitute new rules or new law, going forward they can be expected to significantly influence how Examiners determine obviousness on a day-to-day basis.

Although the stated purpose of the guidelines refers to the 2007 KSR case, the updated guidance first emphasizes that the factual inquiries set forth in the much earlier Supreme Court decision in Graham v. John Deere (1966) continue to control the obviousness determination within the Office: the scope and content of the prior art; the differences between the prior art and the claims at issue; and the level of ordinary skill. Against this background, the obviousness or nonobviousness of the subject matter is determined in light of any so-called secondary considerations such as unexpected results, commercial success, long felt but unsolved needs, failure of others, etc. It is upon this established “Graham framework” that the Office then addresses the ways in which KSR and its Federal Circuit progeny influence this framework.

Here, the guidelines make it very clear that the Office views KSR and its progeny as mandating flexibility in the determination of obviousness, in two respects: “first with regard to the proper understanding of the scope of the prior art, and second with regard to appropriate reasons to modify the prior art.” As concerns the proper (i.e., flexible) understanding of the prior art, the guidelines emphasize that a person of ordinary skill is “a person of ordinary creativity, not an automaton” who has “common sense, which may be used to glean suggestions from the prior art that go beyond the primary purpose for which that prior art was produced” and to make “reasonable inferences” and “be able to fit the teachings of multiple patents together like pieces of a puzzle.” With regard to a flexible approach in providing a reason to modify the prior art the guidelines disavow any type of formalistic or formulaic approach, such as the teaching, suggestion, and motivation (TSM) test, in favor of any possible source that “may, either implicitly or explicitly, provide reasons to combine or modify the prior art to determine that a claimed invention would have been obvious” including market forces, design incentives, the interrelated teachings of multiple patents, any need or problem known in the field of endeavor at the time of invention and addressed by the patent, and the background knowledge, creativity, and common sense of the person of ordinary skill.

Finally, and in summing up, the guidelines note the requirement that the Examiner provide a “clear articulation of the reason(s) why the claimed invention would have been obvious,” warning that “common sense—whether to supply a motivation to combine or a missing limitation—cannot be used as a wholesale substitute for reasoned analysis and evidentiary support, especially when dealing with a limitation missing from the prior art references” and emphasizing that all relevant evidence, including objective indicia of nonobviousness, must be considered in making the obviousness determination.

On balance, these guidelines do not substantially change what we currently see from Examiners in the chemical arts, so why publish them now? Are we about to see an even more “flexible” approach to obviousness? We think (hope) not. Instead, we believe that these guidelines have been published to make the determination of obviousness more consistent throughout the various technical areas of the Office, including the mechanical and electrical arts where, in our limited experience, the amendments and rebuttal arguments necessary to overcome obviousness rejections are perhaps not as significant, or as convincing, as those necessary for success in the chemical arts.

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.

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.

Judges: C. Q. Timm, G. C. Best, and N. W. Wilson

Mylan Pharm. v. Merck Sharp & Dohme Corp., No. 2021-2121 (Fed. Cir. Sep. 29, 2022), is a recent decision of the Federal Circuit considering, inter alia, whether a prior art disclosure of a genus of salts was sufficient to anticipate or render obvious a single salt species.

In an Inter Partes Review proceeding before the PTAB, Mylan asserted that claims of a Merck patent were anticipated by or obvious over a prior Merck patent publication, Edmondson. The PTAB concluded that Mylan failed to prove unpatentability, and Mylan appealed. The claims of the Merck patent at issue were directed to sitagliptin dihydrogenphosphate (DHP). Exemplary claims include claims 1, 2, and 4:

1. A dihydrogenphosphate salt of a 4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro [1,2,4]tria-zolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-tri-fluorophenyl)butan-2-amine… or a hydrate thereof.

2. The salt of claim 1 of structural formula II having the (R)-configuration at the chiral center marked with an *

4. The salt of claim 2 characterized in being a crystalline monohydrate.

Edmondson disclosed sitagliptin in a list of 33 compounds. Edmondson further disclosed acids forming pharmaceutically acceptable salts including phosphoric acid in a list of eight preferred acids. Mylan argued that this was sufficient to anticipate claim 1, relying on the reasoning of In re Petering, 301 F.2d 676, 681 (C.C.P.A. 1962) (prior art may be deemed to disclose each member of prior art genus when skilled artisan can “at once envisage each member of this limited class”).

Merck countered that the combined list of 33 compounds and eight preferred salts, taking into account various stoichiometric possibilities, encompassed 957 salts, which was not sufficient for a skilled artisan to “at once envisage” the salt of claim 1.

The Federal Circuit agreed with Merck that Edmondson did not “expressly disclose a 1:1 sitagliptin DHP salt.” The Federal Circuit credited expert testimony (including testimony of Mylan’s own expert) that Edmondson did not direct a skilled artisan to sitagliptin among the list of 33 compounds and did not single out phosphoric acid or any phosphate salt among the enumerated salts. The Federal Circuit noted particularly that the 957 salts of Edmondson was “a far cry from the 20 compounds ‘envisaged’ by the narrow genus in Petering.”

As to obviousness, interestingly, Merck was able to eliminate Edmondson as a reference as to claims 1 and 2 by proving prior invention and relying on the obviousness exception for commonly owned prior art of pre-AIA 35 USC 103(c). However, this approach was not effective as to claim 4, which was limited to a crystalline monohydrate of the (R)-configuration of 1:1 sitagliptin DHP.

As to claim 4, Mylan relied on Edmondson’s indication that the described salts may exist in more than one crystal structure and in the form of hydrates. Mylan further relied on the disclosure in a secondary reference of the pharmaceutical importance and prevalence of crystalline hydrates of pharmaceutical compounds.

The CAFC agreed with the PTAB and Merck that the general teachings of the secondary reference would not have led a skilled artisan to prepare a crystalline monohydrate of the (R)-configuration of 1:1 sitagliptin DHP based on the teachings of Edmondson with a reasonable expectation of success, noting the unpredictability of hydrate formation and function for specific compounds.

The Federal Circuit briefly noted the PTAB’s consideration of Merck’s evidence of unexpected results, but also noted that “there is no need to reach objective indicia of nonobviousness where the petitioner has not made a showing necessary to prevail on threshold obviousness issues.”

Takeaway: During examination, claims directed to chemical compounds and compositions are often rejected over prior art disclosing generic chemical formulae or separate lists of components. The numbers of specific compounds or compositions encompassed by such prior art can be astronomical. The Mylan case provides some tips for arguing over such rejections (preferably without the need to rely on additional experimental results). Possible arguments include identifying the large number of species encompassed by a prior art genus, emphasizing the lack of direction in the prior art toward the specific selections necessary to obtain a claimed compound or composition, and pointing out the difficulty of applying general teachings regarding selection (e.g., of substituents, subcomponents, etc.) to specific compounds or compositions.

Judges: Lourie, Reyna, Stoll

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

Older Posts

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The USPTO Revisits the Determination of Obviousness

The Double-Edged Sword of Reasonable Expectation of Success and Enablement

PTAB Dismisses Examiner’s Request for Demonstration of Criticality

Picking and Choosing – Single Salt Not Unpatentable Over 957 Member Genus

When a Substitution Isn’t Obvious

USPTO Withdraws Proposed Terminal Disclaimer Rule

USPTO Further Delays Non-DOCX Fee Until January 17, 2024