July 15, 2022by Jacob Doughty

LG Elecs. v. Immervision, Inc., No. 2021-2037 (Fed. Cir. July 11, 2022), is a recent decision of the Federal Circuit, considering whether errant information in a prior art reference can be relied upon to demonstrate unpatentability.

LGE challenged an Immervision patent directed to capturing digital panoramic images in an IPR. The Immervision patent claimed, inter alia, a method in which, “… the objective lens compresses the center of the image and the edges of the image and expands an intermediate zone of the image located between the center and the edges of the image.”

In challenging the patent, LGE relied on a prior art U.S. patent, Tada, which did not expressly disclose compressing the center and edges of an image and expanding an intermediate zone, but which included tables setting forth various measurements of specific embodiments of the disclosed lens system. LGE retained an expert who performed calculations based on the measurements and concluded that one of the lens systems of Tada (Embodiment 3) compressed the center and edges of an image and expanded an intermediate zone.

Immervision also retained an expert, who, in the course of performing his own calculations, discovered discrepancies in the measurements for Embodiment 3 of Tada. After some detailed examination of other embodiments of Tada and the Japanese patent application from which priority was claimed, Immervision’s expert determined that the measurements for Embodiment 3 shown in Tada erroneously included measurements for a different embodiment.

That is, due to an apparent cutting-and-pasting error in translating the Japanese application on which Tada was based, LGE’s expert’s calculations indicated that the lens system of Embodiment 3 of Tada compressed the center and edges of an image and expanded an intermediate zone. However, if LGE’s expert had used the correct measurements, this would not have been the case.

Based on the testimony of Immervision’s expert, the PTAB concluded that LGE failed to carry its burden in demonstrating unpatentability. LGE appealed.

The Federal Circuit noted that “… the standard for evaluating these types of apparent or ‘obvious typographical error[s],’” is set forth in a decision of its predecessor court, more than 50 years ago, in In re Yale, 434 F.2d 666 (C.C.P.A. 1970). Particularly:

The court in Yale held that where a prior art reference includes an obvious error of a typographical or similar nature that would be apparent to one of ordinary skill in the art who would mentally disregard the errant information as a misprint or mentally substitute it for the correct information, the errant information cannot be said to disclose subject matter.

In Yale, the CCPA concluded that a reference could not be relied on for disclosing a compound that appeared in a single instance due to an error (CF3CHClBr was shown as CF3CF2CHClBr in a graph).

LGE argued that the error in Tada could not possibly be an obvious error because it took Immervision’s expert hours of detailed investigation to find. LGE further argued that the error in Tada was not “of a typographical or similar nature.” The Federal Circuit was not persuaded. In affirming the PTAB, the Federal Circuit noted that the length of time and manner in which an error was discovered did not diminish its obviousness. Further, the Federal Circuit further stated that “[t]he distinction between the typographical error in Yale and the copy-and-paste error here is a distinction without a difference.”

In dissent, Judge Newman was more sympathetic to LGE’s position:

I agree with the panel majority that Yale establishes the correct standard to determine if an error would be obvious to a person of ordinary skill in the field. However, I do not agree with the majority’s application of this standard to the facts herein. An “obvious error” should be apparent on its face and should not require the conduct of experiments or a search for possibly conflicting information to determine whether error exists. When a reference contains an erroneous teaching, its value as prior art must be determined.

Takeaway: It is not uncommon for technical documents relied on as prior art (e.g., patent publications, journal articles) to include errors – particularly in descriptions of experimental results. Such errors may undermine an assertion that a property or parameter is inherent – and thus possibly provide an avenue for attacking a prior art rejection or assertion of invalidity.

Judges: Newman (dissenting in part), Stoll, Cunningham


June 10, 2022by Jacob Doughty

Pavo Sols. v. Kingston Tech. Co., No. 2021-1834 (Fed. Cir. June 3, 2022), is a recent decision of the Federal Circuit considering, inter alia, whether a district court acted appropriately in “judicially correcting” an error in claim language. Kingston was found by the district court to have willfully infringed the judicially corrected claim.

The claim at issue recited:

A flash memory apparatus comprising:

a flash memory main body including a rectangular shaped case within which a memory element is mounted, a[] USB (Universal Serial Bus) terminal piece electrically connected with the memory element and installed at a front end of the case in a projecting manner, and a hinge protuberance formed on at least one side of the case; and

a cover including [a] pair of parallel plate members facing each other and spaced by an interval corresponding to the thickness of the case, the cover having an open front end and a closed rear end with a pair of lateral side openings; the parallel plate members having at least one hinge hole receiving the hinge protuberance on the case for pivoting the case with respect to the flash memory main body, whereby the USB terminal piece is received in an inner space of the cover or exposed outside the cover.

As emphasized above, the claim requires cover features that permit the case to pivot with respect to the flash memory main body.  However, the case is part of the flash memory main body and not part of the cover, so it is unclear how the features of the cover could cause a part of the flash memory main body to pivot with respect to itself (or another part thereof). The district court found that it was apparent from the claim language that “pivoting the case” should be “pivoting the cover” and judicially corrected the language in its claim construction order.

The Federal Circuit noted that it is permissible for a court to correct “an obvious minor typographical or clerical error” in a patent claim “only if (1) the correction is not subject to reasonable debate based on consideration of the claim language and the specification and (2) the prosecution history does not suggest a different interpretation of the claims.”

Kingston argued that the error could not possibly be minor because the correction replaced one structural element with another and broadened the claims. Kingston further argued that alternative corrections were plausible in view of the claim language, specification, and prosecution history.

The Federal Circuit found that its precedent did not prohibit corrections that resulted in changes to recited structure. Further, the Federal Circuit found Kingston’s arguments with respect to broadening and plausible alternative corrections (and the supporting expert testimony) to be insufficient to raise a reasonable debate about claim scope.

Having affirmed the district court’s correction of the claim, the Federal Circuit concluded that the district court’s finding of willful infringement was also appropriate. Specifically, “[w]e hold, however, that reliance on an obvious minor clerical error in the claim language is not a defense to willful infringement.”

Takeaway: When performing a clearance or freedom-to-operate analysis, patent counsel often search for “errors” made in drafting or prosecution of a patent application that could result in a narrow construction or estoppel that will give a client comfort that a finding of infringement is unlikely. However, it is important not to be too strict or literal in this analysis. If the intended meaning of claim term is clear using common sense, it may be risky to base a conclusion of non-infringement on errors in a claim even if they seem significant.

Judges: Lourie, Prost, Chen


May 6, 2022by Jacob Doughty

Niazi Licensing Corp. v. St. Jude Med. S.C., No. 2021-1864 (Fed. Cir. Apr. 11, 2022), is a recent decision of the Federal Circuit considering, inter alia, the definiteness of descriptive words (or terms of degree) in a claim.

The claim at issue recited:

A double catheter, comprising:

an outer, resilient catheter having shape memory and a hook shaped distal end configured for cannulation of the coronary sinus with at least one curved bend;

an inner, pliable catheter slidably disposed in the outer catheter and of greater length than the outer catheter…

The district court found that the terms “resilient” and “pliable” rendered the claim invalid as indefinite. The Federal Circuit disagreed and reversed.

The Federal Circuit began by noting that, while terms of degree in a claim may inherently result in broader claim scope, a claim is not indefinite just because it is broad. However, terms of degree will render a claim indefinite when the intrinsic evidence (or extrinsic evidence, when relevant and available) provides insufficient guidance as to any objective boundaries for the claim – i.e., when claim scope is “purely subjective.”

With respect to the term “resilient,” the Federal Circuit found that the claim itself provided guidance with respect to the meaning of the term by requiring that the outer catheter have “shape memory.” Dependent claims further indicated exemplary materials that could be used to make the outer catheter. Likewise, the specification indicated that the outer catheter should have “sufficient shape memory to return to its original shape when un-distorted.” Although the Federal Circuit indicated that reliance on extrinsic evidence was not necessary, dictionary definitions were consistent with the claims and specification. Thus, the Federal Circuit concluded that a skilled artisan reading the claims and specification would know of exemplary materials that can be used to make a resilient outer catheter, i.e., one that has shape memory and stiffness such that it can return to its original shape.

As to “pliable,” the claim language was not as illuminating, but the specification indicated that, relative to the outer catheter, the inner catheter “is constructed of a more pliable, soft material such as silicone.” Dictionary definitions, again, were consistent with the specification. The Federal Circuit found that a skilled artisan would have understood that the inner catheter is made of a more flexible material than the outer catheter.

Thus, the Federal Circuit concluded that the intrinsic and extrinsic record provided objective boundaries by which a skilled artisan could determine the scope of the claims. The terms “resilient” and “pliable” were determined not to be “purely subjective terms,” resulting in a variable claim scope depending on the particular eye of any one observer.

Takeaway: Terms of degree in a claim can be troublesome during prosecution – an examiner can easily make a rejection, and a response proving “objective boundaries” can be difficult. However, if a term of degree cannot be deleted, the Niazi decision provides some suggestions for responding to an assertion of indefiniteness. Any indications of the scope of the term from the claims and specification can be supplemented with evidence (literature, opinion declaration, etc.) of how a skilled artisan would view the term. Although not explicitly stated in the Niazi decision, the court’s reasoning suggests that an explanation of why terms do not overlap in scope can be particularly persuasive.

Judges: Taranto, Bryson, Stoll


April 1, 2022by Jacob Doughty

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


January 20, 2022by Jacob Doughty

Ex parte Myers is a recent decision of the Patent Trial and Appeal Board (PTAB) addressing enablement and written description of a claim amended to recite a range during prosecution.

The claim at issue recited:

A composition comprising oolitic aragonite particles, wherein the oolitic aragonite particles have an average particle size of between 100 nm to 1 mm, and a median (D50) particle size distribution (PSD) of between 2.0 to 3.5 μm, and a Hunter brightness level greater than 90.

The Hunter brightness feature was added during prosecution to distinguish over prior art. Applicant asserted that the following disclosure in the specification enabled and supported the newly added feature:

[T]he size of (milled) aragonite will also have a substantial effect on brightness of the material. For example, when milled to a fine particle size of 2 to 8 micron, the Hunter brightness level is approximately 94, which is very bright white. Thus, by selecting a suitable particle size, brightness of the milled aragonite can be adjusted.

The foregoing was the only disclosure of any Hunter brightness level – only a single value and no disclosure of any range.

The examiner acknowledged the disclosure of a single value of 94 for Hunter brightness level but asserted that such disclosure did not reasonably provide enablement for, or demonstrate possession of, the entire range of “greater than 90.”

As to enablement, the PTAB disagreed with the examiner, finding that the examiner had failed to establish that undue experimentation would be required for a skilled artisan to make and use the claimed composition. The PTAB appeared to find plausible applicant’s contention that disclosure of a single Hunter brightness level paired with disclosure that milling or otherwise adjusting particle size affects Hunter brightness would be enabling.

However, as to written description, the PTAB affirmed the examiner’s rejection. Applicant asserted that the particles described in the specification inherently have Hunter brightness values between 90 and 100. The PTAB noted that, while the specification indicated that particle size related to Hunter brightness, there was nothing in the record to indicate that the particles sizes in the specification necessarily resulted in Hunter brightness values greater than 90. The PTAB further noted that the specification indicated that parameters other than particle size influence Hunter brightness, concluding that the specification did not reasonably convey that applicant was in possession of the recited range of Hunter brightness levels.

Takeaway: US practice is much more flexible than other jurisdictions with respect to the degree of specification disclosure required to support claim amendments made during prosecution. This is especially true when amending ranges to include new endpoints from subranges and/or individual examples in the specification (but keep an eye on the Federal Circuit link, link). However, even under US practice, it will be difficult to create a claimed range from a single data point. If a parameter is important enough to identify in a patent application, it is worth the small additional effort to identify ranges of values that encompass the described invention.

Judges: Hanlon, Gupta, Inglese


December 13, 2021by Jacob Doughty

AstraZeneca AB v. Mylan Pharm., 2021-1729 (Fed. Cir. Dec. 8, 2021), is a recent decision of the Federal Circuit interpreting the scope of a numerical limitation in a claim.

The claims on appeal in AstraZeneca were directed to pharmaceutical formulations for administration via pressurized metered dose inhalers. The formulations required a formulation stabilizer, PVP K25, and recited “the PVP K25 is present at a concentration of 0.001% w/w.”

The district court interpreted 0.001% w/w as encompassing 0.001% w/w “within one significant figure” – i.e., any value that could be rounded up or down to 0.001% w/w, or 0.0005% to 0.0014% w/w. The Federal Circuit disagreed and interpreted 0.001% w/w as “that precise number, with only minor variations” – i.e., 0.00095% to 0.00104% w/w. A further alternative was offered in Judge Taranto’s dissent.

The Federal Circuit indicated that, in the abstract, the ordinary meaning of 0.001% w/w was consistent with the district court’s interpretation of 0.0005% to 0.0014% w/w (“This is a standard scientific convention, and numbers falling within that range would typically be rounded up or down to 0.001%.”). However, the Federal Circuit found that

…taken as a whole, the intrinsic record supports a narrower construction of 0.001% to reflect that term’s application to the PVP concentration in particular, and the testing evidence in the written description and prosecution history showing that very minor differences in the concentration of PVP—down to the ten thousandth of a percentage (fourth decimal place)—impact stability.

Of particular importance to the Federal Circuit were experimental results in the specification showing significant changes in stability between a composition including 0.001% w/w PVP and a composition including the more precisely defined 0.0005% w/w PVP. The patentee made arguments about the results during prosecution and cancelled claims reciting, e.g., “0.0001% to 0.001% w/w” PVP and “0.0001%, 0.0005%, or 0.001% w/w” PVP. The Federal Circuit further noted that the patentee could have used the term “about” to modify of 0.001% w/w but chose not to.

Based on the Federal Circuit’s construction, the case was remanded for further consideration of infringement.

In his dissent, Judge Taranto found the majority’s approach too exacting. He argued that the disclosure of more precise values in the specification (e.g., 0.0005% w/w PVP) was not a disclaimer of the ordinary meaning of 0.001% w/w PVP. In Judge Taranto’s view, applicant’s arguments during prosecution with respect to stability at most required an exclusion of 0.0005% w/w PVP from the literal scope of 0.001% w/w.

Takeaway: This decision – particularly when the majority and dissent opinions are compared – does not offer much clarity as to how precisely a numerical value in a claim will be interpreted. There appears to be consensus that the starting point is “within one significant figure.” However, based on the majority’s decision, even the mention of more precise values in the specification or prosecution history can impute an additional significant figure to a claimed value. Practitioners should at least be wary of the risks of using different degrees of precision for different data points/values in the specification and claims and consider explicitly defining the degree of error intended for claimed values in the specification.

Judges: Taranto, Hughes, Stoll (Taranto dissenting)


November 5, 2021by Jacob Doughty

Ex parte Kuhlmann, is a recent decision of the Patent Trial and Appeal Board (PTAB) addressing prima facie obviousness of a polymer composition.

The substance of the decision in Ex parte Kuhlmann is not particularly remarkable – the examiner was affirmed by the PTAB. However, applicant argued that the allowance of a corresponding application in Europe was relevant to the issue of obviousness in the US, and the argument was not well-received.

In the Appeal Brief, applicant argued:

For reference, the Applicants respectfully submit that the EPO equivalent application EP 3255103 was granted and found to be novel and non-obvious over the US Dangayach et al. (US 5,284,938, herein Dangayach A) reference.

In the Examiner’s Answer, the examiner stated:

In response to Appellant’s statement, p. 9 of the Brief, that EP 3255103 was found novel and non-obvious over the Dangayach A is not persuasive, because that determination was not under US patent laws and rules.

In the Reply Brief, applicant further argued:

If relevant to the Appeal Board, the Appellants submit that the claims as submitted in the Appeal are identical or substantially identical to the claims granted (without issuance of an Action) in European patent EP3255103B1 and validated in 14 countries, which claims were granted over Dangayach et al. (US 5,284,938, herein Dangayach A), the main reference cited by the Examiner herein, for reasons which will further be obvious below.

And finally, in the Decision, the PTAB stated:

We find no merit in Appellant’s argument that the same or substantially the same claims in EP 3255103 B1 were found novel and nonobvious over Dangayach and thereby granted by the European Patent Office (EPO)… We are not bound by an earlier decision of the EPO. In re Gyurik, 596 F.2d 1012, 1016 (CCPA 1979) (“Each case is determined on its own merits; allowed claims in other applications or patents are not considered in reviewing specific rejections of specific claims.”); In re Giolito, 530 F.2d 397, 400 (CCPA 1976) (“We reject appellants’ argument that the instant claims are allowable because similar claims have been allowed in a patent. It is immaterial whether similar claims have been allowed to others.”).

Takeaway: Prosecuting corresponding patent applications in different countries can be expensive and time consuming. Common sense would suggest that something that is patentable in one jurisdiction should generally be patentable in all jurisdictions. Of course, the patent laws differ from jurisdiction-to-jurisdiction. The US can be particularly idiosyncratic, as US examiners often rely on different references and/or rationales than examiners in other jurisdictions. As is evident from Ex parte Kuhlmann, directly asserting that US claims should be allowed based on an allowance in another jurisdiction can be counterproductive. A more productive approach would be to rely on the reasons for allowance in another jurisdiction to the extent they are applicable under US law. The fact of allowance in another jurisdiction might be of interest to some US examiners – but this might be better conveyed informally in an interview.

Judges: Timm, Praiss, Gupta


October 29, 2021by Jacob Doughty

Ex parte Lindenblatt, is a recent decision of the Patent Trial and Appeal Board (PTAB) addressing evidence of unexpected results.

In Ex parte Lindenblatt, the claim at issue was directed to a pharmaceutical (thyroid hormone) formulation. The relevant claim recited:

1. A solid pharmaceutical preparation comprising

levothyroxine sodium,

2-10% by weight based on the preparation of gelatine,

0.2 to 3% by weight based on the preparation of citric acid, and

a filler that is 50 to 80% by weight, based on the preparation, of mannitol, sucrose or lactose, and 10 to 30% by weight, based on the preparation, of maize starch.

In rejecting the claim, the examiner relied on a primary reference that disclosed all of the features except for the gelatin. For this deficiency, the examiner relied on a secondary reference disclosing levothyroxine sodium tablets including gelatin and fillers and describing that, when gelatin is used as a binder, the tablets have surprising stability.

Applicant argued that the tablet of the primary reference was intended to dissolve rapidly in a patient’s mouth and, thus a skilled artisan would not have been led by the secondary reference’s promises of stability through the use of gelatin.

The PTAB was not persuaded, finding that the examiner made a prima facie case of obviousness. The PTAB noted particularly that “while [the primary reference] is concerned with a composition that can easily dissolve in the mouth, such does not indicate that [the primary reference] is not interested in a product that has a stable shelf life until inserted into the mouth of a patient.”

The PTAB was persuaded, however, by applicant’s evidence of unexpected results.

First, applicant provided evidence (a journal article) showing that it was known that citric acid is a pH modifier that reduces the stability of levothyroxine sodium in tablets relative to tablets including a basic pH modifier or no pH modifier (at 10% – much higher than the claimed range and the primary reference). Then, applicant supplemented with experimental evidence, which showed the following results for stability when varying citric acid and gelatin amounts in levothyroxine sodium tablets:

Citric Acid Gelatin Stability
5% ★★★
1.5% 5% ★★★★

Looking at the evidence, the PTAB found that the stability results for the combination of gelatin and citric acid would have been unexpected, because citric acid alone was reported in the literature and shown in applicant’s experimental results to negatively affect the stabilization of levothyroxine sodium in a tablet. That is, the PTAB concluded that a skilled artisan would not have expected the combination of citric acid and gelatin to provide better stabilization of levothyroxine sodium in a tablet composition than the stabilization provided by gelatin alone.

Takeaway: In this case, the examiner provided a credible reason for expecting that addition of gelatin to the citric acid-containing tablets of the primary reference would increase stability – the secondary reference explicitly stated that stability would be increased. Applicant was able to find literature evidence suggesting that a large amount of citric acid is expected to destabilize. Applicant supplemented this with post-filing results showing that small amounts of citric acid destabilize. Together, this evidence persuaded the PTAB that the improved performance of the citric acid/gelatin combination shown by applicant was unexpected.

Applicant provided a good amount of evidence and a compelling narrative regarding unexpectedness. The PTAB’s explanation, however, gives little weight to the fact that the primary reference tablets already included citric acid. Further, the post-filing evidence regarding the effect of small amounts of citric acid would not have informed a skilled artisan of what would have been expected or unexpected at the time of the application. This case illustrates that sometimes a persuasive story can be useful in overcoming weaknesses in evidence of unexpected results.

Judges: Adams, Jenks, Townsend


September 24, 2021by Jacob Doughty

Ex parte Slark, is a recent decision of the Patent Trial and Appeal Board (PTAB) addressing whether the changes to a prior art composition that would result from an examiner’s proposed modification were sufficiently dramatic to negate obviousness.

In Ex parte Slark, the claim at issue was directed to a hot melt adhesive composition. The relevant claim recited:

A non-reactive hot melt adhesive composition comprising two thermoplastic polyurethane copolymers (A) and (B), wherein

the thermoplastic polyurethane copolymer (A) comprises a reaction product of at least one polyester polyol, and at least one polyisocyanate, and has a number average molecular weight (Mn) of at least 25,000 g/mol;

the thermoplastic polyurethane copolymer (B) comprises a reaction product of at least one polyester polyol, and at least one polyisocyanate, and has a number average molecular weight (Mn) of less than 25,000 g/mol; and

wherein the hot melt adhesive composition has a melt viscosity of 1,000 to 100,000 mPas at 160 °C and

wherein both thermoplastic polyurethane copolymers (A) and (B) are essentially free of NCO groups.

The examiner cited a primary reference that disclosed a solvent-free hot melt adhesive composition including two thermoplastic polyurethane copolymers, each copolymer being a reaction product of at least one polyester polyol and at least one polyisocyanate. The examiner acknowledged that the primary reference failed to disclose that the hot melt adhesive was non-reactive or that the polyurethane copolymers were essentially free of NCO groups. The examiner noted particularly that the preferred ratio of NCO groups to OH groups in the copolymers of the primary reference (>1) would not result in a “non-reactive” composition in which the copolymers were “essentially free of NCO groups.”

To address this deficiency, the examiner turned to a secondary reference. The secondary reference disclosed a solvent-free hot melt adhesive composition including a polyurethane obtained from a polyester polyol and an isocyanate, in which the ratio of NCO groups to OH groups in the polyurethane (~1) resulted in a “non-reactive” composition in which the polyurethane was “essentially free of NCO groups.” The examiner asserted that it would have been obvious to modify the polyurethanes of the primary reference to have the NCO:OH ratio of the polyurethane of the secondary reference, because the secondary reference disclosed that the ratio was suitable for reacting a polyester polyol with a polyisocyanate such that the resulting hot melt adhesive would be essentially free of NCO groups and nonreactive.

Applicant argued over the rejection by relying on two non-obviousness arguments that are explicitly identified in the MPEP: (1) modifying the composition of the primary reference as proposed by the examiner would render the composition “unsatisfactory for its intended purpose” (MPEP 2143.01.V); and (2) modifying the composition of the primary reference as proposed by the examiner would “change the principle of operation” of the composition (MPEP 2143.01.VI).

With respect to (1), applicant argued that the primary reference was directed to a reactive thermoset hot melt adhesive composition – not a non-reactive thermoplastic composition as required by the claims. Applicant noted that the purpose of the primary reference was to provide a moisture reactive polyurethane hot melt adhesive having a particular cured strength and excellent adhesion to metals. Applicant argued that the examiner’s proposed modification would eliminate essentially all of the isocyanate moieties in the prepolymers, rendering them non-reactive and unsatisfactory for the intended purpose of the primary reference. With respect to (2), applicant similarly argued that, because the examiner’s proposed modification involved eliminating the isocyanate groups from the prepolymers, the principle of operation of the composition of the primary reference would be different – the composition would no longer be a reactive, moisture-curable thermosetting polyurethane adhesive composition.

The PTAB agreed with applicant. The PTAB indicated that the “intended purpose” and “principle of operation” of the adhesive composition of the primary reference were intertwined. The examiner attempted to broadly characterize the composition of the primary reference as involving adhesion – an intended purpose and principle of operation that would be preserved even if the examiner’s proposed modification was made. However, the PTAB indicated that the examiner should have considered the contribution of the primary reference to the art when identifying the intended purpose and principle of operation. The PTAB noted that the primary reference expressly stated that mixtures of isocyanate-terminated polyurethanes provide good adhesion to metal substrates by achieving an initial bond strength upon cooling on a substrate and eventually achieving an ultimate bond strength when cured with ambient moisture. The PTAB agreed with applicant that the examiner’s proposed modification would render the composition of the primary reference unsatisfactory for its intended purpose and would change the principle of operation.

Takeaway: When facing obviousness rejections of chemical compositions, it can be difficult to persuade an examiner that he or she has failed to make a prima facie case. Absent a plain oversight by the examiner regarding the scope of the claims or prior art, it is often necessary to significantly narrow the scope of the claims and/or rely on experimental evidence of unexpected results. However, there are legal arguments that can be effective in overcoming obviousness arguments without amendments or experimental results – and the MPEP remains a great source for identifying compelling reasoning for arguing over obviousness rejections.

Judges: Hanlon, Housel, Inglese


August 3, 2021by Jacob Doughty

Ex parte Ratcliff, is a recent decision of the Patent Trial and Appeal Board (PTAB) addressing whether the requirement that a component of a claimed composition “remains stable in the composition” was indefinite.

In Ex parte Ratcliff, the claim at issue was directed to an oral rinse composition. The relevant claim recited:

An oral rinse composition for enhancing tooth remineralization, comprising:

stabilized chlorine dioxide that remains stable in the composition, the stabilized chlorine dioxide capable of reacting with acidic elements of oral biofilms to produce chlorine dioxide gas;

sodium fluoride; and

a pharmaceutically acceptable buffer effective at establishing an effective pH range of the composition from about 6.0 to about 7.4 for maintaining the stability of the chlorine dioxide in the composition;

wherein the stabilized chlorine dioxide and the sodium fluoride in combination are more effective at enhancing tooth remineralization and reducing tooth demineralization than either of the stabilized chlorine dioxide or the sodium fluoride alone.

In this case, the examiner took issue with the above-emphasized phrase “stabilized chlorine dioxide that remains stable in the composition.” Particularly, the examiner asserted that “… the claim does not provide a discernable boundary on what provides the functional characteristic to the stabilized chlorine dioxide (SCD),” wondering whether stabilized chlorine dioxide is stable in the composition:

… due to the addition of some other structure (such as pH modifiers, stabilizers, etc.), absence of destabilizing agents (such as stannous chloride), other features of the composition (such as specific pH ranges)… due to a sequence of steps by which it is made or by some other means, or a certain combination of these.

Applicant argued that “stability” was adequately defined in the specification as the “ability to maintain levels of the… chlorine dioxide source… within the levels specified by the present invention when the final composition is placed under…” specified storage conditions. However, the PTAB noted that the “levels specified by the present invention” were not defined in the claim or specification (or identified by applicant in its appeal briefing).

The PTAB searched the specification for further guidance and found a general disclosure of amounts of the chlorine dioxide source (0.005% w/w to 0.800% w/w) and disclosure that a reduction in the amount of stabilized chlorine dioxide after storage (0.125% w/w >> 0.04% w/w) indicated that stability was achievable. However, the PTAB found that there was insufficient guidance in the specification regarding “how much stabilized chlorine dioxide must remain in the composition after being stored under the specified conditions, in order to be stable according to the definition of stability provided in [the specification].” Thus, the PTAB affirmed the examiner, finding the claim so ambiguous that it failed to inform a skilled artisan about the scope of the claimed invention with reasonable certainty.

The PTAB reversed the only other rejection on appeal – an obviousness rejection. However, this was a pyrrhic victory. The PTAB stated that “the scope of the claimed subject matter is so uncertain that we cannot meaningfully perform the required comparison between the composition recited in [the claim] and the compositions of the cited prior art.”

Takeaway: It was apparent in this case that the PTAB was looking for a number – how much stabilized chlorine dioxide would need to remain in the composition after storing under specified conditions for the stabilized chlorine dioxide to be deemed “stable in the composition”? For claims as in this case, it can be helpful to consider how the difference between “stable” and “not stable” will be explained to a lay jury. If it will be hard to show a lay jury the line between infringing and not infringing, it may be preferable to claim the composition differently (maybe product-by-process).

In this case, both the examiner and the PTAB relied on their own judgment of how a skilled artisan would have viewed the meaning of stability. While applicant provided experimental evidence to show that certain prior art compositions did not include stabilized chlorine dioxide that remains stable, a succinct statement from a skilled artisan regarding how to determine whether stabilized chlorine dioxide “remains stable in the composition” may have framed the issue of indefiniteness in a more favorable manner.

Judges: Adams, Prats, Townsend