March 6, 2024by Richard Treanor

In May of 2023 the U.S. Supreme Court in Amgen v. Sanofi unanimously found that claims drawn to any antibody that could 1) bind to at least two specified residues of a certain protein and 2) block the binding of the protein to a certain receptor by at least 80% were invalid for lack of enablement. In doing so, the court found patentee’s 26 specific examples and two disclosed methods for finding other examples insufficient to enable “an entire class of things defined by their function.” In Amgen the Supreme Court made it clear that claiming everything – an entire class – by only its function is not allowed unless the specification also discloses “some general quality . . . running through” the class that gives it “a peculiar fitness for the particular purpose.” The court also made it clear that only when this “general quality” is present may the specification then call for a reasonable amount of experimentation to make and use a patented invention.

The U.S. Patent and Trademark Office (USPTO) has recently issued Guidelines for assessing enablement in view of Amgen, setting forth the USPTO’s position. These Guidelines make it clear that the USPTO understands that the ruling in Amgen:

1) applies to all technologies and all types of claims, and

2) confirms that USPTO personnel should continue to use the several “factors” established in In re Wands, 858 F.2d 731, 737 (Fed. Cir. 1988) when assessing enablement – i.e., when assessing whether only a “reasonable” amount of experimentation (Amgen, Supreme Court) or “undue amount” of experimentation (Wands, Federal Circuit) would be required to practice the full scope of the claims.

As a reminder, the Wands factors include, but are not limited to: (A) the breadth of the claims, (B) the nature of the invention, (C) the state of the prior art, (D) the level of one of ordinary skill, (E) the level of predictability in the art, (F) the amount of direction provided by the inventor, (G) the existence of working examples, and (H) the quantity of experimentation needed to make and use the invention based on the content of the disclosure.

In one sense, the USPTO has essentially said, regarding Amgen, that “there is nothing to see here.” On the other hand, however, Amgen can be seen as effectively putting an end to functional claiming in the absence of what will likely be claim-narrowing specification disclosure of “some general quality . . . running through” the functionally claimed class that gives it its “peculiar fitness for the particular purpose.” Thus, Amgen can be viewed as a “reigning in” of a claiming strategy typically used in the early and quickly developing stages of a new technology, when prior art is often unavailable to provide a moderating effect on claim scope.


June 5, 2023by Richard Treanor

Recently, the U.S. Supreme Court in Amgen Inc. v. Sanofi, 598 U.S. ___ (May 18, 2023) spoke with one voice in finding claims drawn to any antibody that could do two things – 1.) bind to at least two specified residues of the protein PCSK9 and 2.) block the binding of PCSK9 to the low density lipoprotein receptor gene by at least 80% – invalid for lack of enablement. In doing so, the court found patentee’s 26 specific examples and two disclosed methods for finding other examples insufficient to enable “an entire class of things defined by their function.”

In its analysis the court first reviewed several famous historical U.S. patent cases including the telegraph invented by Morse and the lightbulb invented by Edison that in their view established the concept that claiming everything – an entire class – that provides a certain function is not allowed unless the specification “also discloses ‘some general quality . . . running through’ the class that gives it ‘a peculiar fitness for the particular purpose.’” Only when this general quality is present, the “specification may [then] call for a reasonable amount of experimentation to make and use a patented invention. What is reasonable in any case will depend on the nature of the invention and the underlying art.”

In reviewing Amgen’s specification the Court found that it failed to identify the required “general quality . . . running through” the claimed class of antibodies that provided their “peculiar fitness” for their claimed functions, and found Amgen’s “roadmap” and “conservative substitution” methods to be “little more than two research assignments” amounting to random trial-and-error. For these reasons, the Court found the Amgen claims to be invalid as not enabled.

The Amgen case thus provides us with good guidance for enabling broad claims generally, and especially broad, functional claims  – the importance of describing a “general quality” applicable to the claimed class that gives it a “peculiar fitness” for the claimed purpose.

Only time will tell, but how this case will be applied to traditional chemical cases will be interesting to watch. Will a well-defined chemical “core” be sufficient for a Markush group potentially including 500,000 members? Maybe, with the answer probably depending at least in part on how much “detailed” core there is, and its distinctiveness. Clearly, cores described as “A-B-C” with definitions and sub-definitions for each will face an uphill battle, and probably represent one end of the chemical spectrum (the difficult end) whereas a sterol core, even with several substituents, and many choices of substituents, probably represents the other end.


January 20, 2023by Matthew Barnet

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

Independent claim 1 in During recited:

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

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

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

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

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

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

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

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

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

Judges: Fredman, Jenks, Chang

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


September 9, 2022by Jacob Doughty

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

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

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

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

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

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


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

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

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

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

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

Judges: Owens, Hastings, Range


July 21, 2022by Beau Burton

A specification must enable one of ordinary skill in the art to practice the full scope of the claimed invention. But as noted by the Federal Circuit, “[t]hat is not to say that the specification itself must necessarily describe how to make and use every possible variant of the claimed invention, for the artisan’s knowledge of the prior art and routine experimentation can often fill gaps, interpolate between embodiments, and perhaps even extrapolate beyond the disclosed embodiments, depending upon the predictability of the art.”

A recent decision from the Patent Trial and Appeal Board, Ex parte Seppo, shows the interplay between enablement and a skilled artisan’s ability to extrapolate beyond potentially inoperative embodiments.

In Seppo, the claims covered a method of generating a composite image of a region of a human tissue sample by generating a first image by binding a human target protein-specific monoclonal antibody labeled with a fluorophore and detecting the bound fluorophore; generating a second image by hybridizing a nucleic acid probe labeled with a fluorophore and detecting the hybridized probe fluorophore; and generating a composite image by registering fluorescent signals from the first image with fluorescent signals from the second image.

The Examiner took issue with a theoretical embodiment involving the use of the same fluorescent label/marker/signal for both steps, stating:

If the label used for the monoclonal antibodies and the label used on the nucleic acid probes is the same … one would not be able to accurately and reproducibly >>register<<, in a composite image, the fluorescent signals from each of the different binding reactions, as they would all be the same.

The Examiner further noted that the examples in the specification used multiple labels on different antibodies and nucleic acid probes, but failed to show how to obtain a composite image with the same fluorescent label – an embodiment covered by the independent claim. Accordingly, the Examiner found “the specification, while being enabling for the method of claim 1 wherein different fluorophores are used … does not reasonably provide enablement for use of the same fluorescent label/marker/signal for all steps.” The Board disagreed.

First, the Board found that although the Examiner “has posited one variant of the claimed method … that in his view would not yield useful information … the Examiner’s reasoning itself suggests that a skilled artisan would expect that embodiment to be of limited or perhaps no utility, and thus those in the art would have known to avoid it.”

Second, the Board noted that the Examiner’s reasoning at best identified a single inoperative embodiment encompassed by the claim, while Federal Circuit precedent suggest that number must be significant and force one of skill in the art to experiment unduly in order to practice the claimed invention. Absent a persuasive showing that undue experimentation would be required to practice the claimed method, the Board reversed the rejection.

Takeaway: When an Examiner alleges that a claim does not satisfy the enablement requirement because it encompasses one or more inoperative embodiments, the Examiner must show that the inclusion of inoperative embodiments is so significant that a skilled artisan would be forced to experiment unduly. In Seppo, the Examiner’s rationale folded on itself because the Examiner admitted that a skilled artisan would have expected his single, hypothetical inoperative embodiment to provide limited information such that a skilled artisan would know to avoid it.

Judges: D. Adams, E. Grimes, J. Fredman


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


March 26, 2021by Yanhong Hu

In Ex parte Hassler (Appeal 2020-001367), the Patent Trial and Appeal Board (“Board”) considered Appellant’s two arguments rebutting the Examiner’s obviousness rejection based on the combination of the primary reference (Fischmann) with the secondary reference (McNew).

Independent claim 1 illustrated the subject matter of the appealed claims and was directed to a method that included a step (a) of receiving an oxyanion-containing water comprising at least one non-metal-containing oxyanion and a subsequent step (b) of contacting the oxyanion-containing water with a separate rare-earth-element-containing component to remove more than 50% of the oxyanions from the oxyanion-containing water.  The claim further limited the non-metal-containing oxyanion to an anion that contained one or more particular species recited in a Markush group.

The Examiner admitted Fischmann, which disclosed step (a), failed to teach a separate component containing a rare-earth element as claimed in step (b) and thus resorted to McNew for the admitted deficiency.  Appellant first argued Fischmann did not constitute prior art because the claimed subject matter enjoyed priority to applications that predated Fischmann.  Secondly, Appellant argued even if Fischmann constituted prior art, the Examiner’s substitution of McNew’s composition into the process of Fischmann was improper.

The Board reversed the obviousness rejection because the Board agreed with Appellant’s second argument.  However, the Board sided with the Examiner regarding Appellant’s first argument.  The Board’s analysis of Appellant’s first argument involving the written description and enablement requirements of 35 U.S.C. § 112(a) (or pre-AIA § 112, ¶ 1) is the focus of this blog.

Appellant argued the application at issue had an earlier effective filing date because it claimed priority to two provisional applications (“the Hassler provisionals”), which incorporated by reference three earlier filed non-provisional applications (“the incorporated applications”).  Appellant argued all the incorporated applications and the Hassler provisionals defined the terms “oxyanion” and “target material-containing oxyanion” in the same way.

The Examiner contended the claim could not be afforded priority of the Hassler provisionals because the Hassler provisionals did not support the claimed subject matter in a manner that complied with the written description requirement of § 112(a).  The Examiner explained the Hassler provisionals merely described the oxyanions generally as AxOy with A being a metal, metalloid, or non-metal but did not disclose any species of non-metal oxyanions other than selenium.  The Examiner similarly found the incorporated applications failed to disclose the Markush species recited in claim 1.

Appellant did not dispute the Examiner’s contention that the Hassler provisionals failed to expressly disclose the particular Markush species.  However, Appellant argued “the fact that the Hassler provisionals do not define non-metal oxyanions other than selenium oxyanions as ‘target-material containing’ oxyanions does not limit the scope of the genus of ‘oxyanions’ generally [described therein].”  Appellant continued, “it [is] well known to those of ordinary skill in the art that the term ‘oxyanion’ referred to any anion ‘containing one or more oxygen atoms bonded to another element.’”  Citing Regents of the University of California v. Eli Lilly, 119 F.3d 1559, 1568 (Fed. Cir. 1997) and relevant MPEP sections, Appellant further argued that “in assessing a disclosure for compliance with 35 U.S.C. § 112(a), … ‘[w]hat is conventional or well known to one of ordinary skill in the art need not be disclosed in detail’” and that the general chemical formula AxOyz- disclosed in the Hassler provisionals eliminated any ambiguity in that “such a formula, even standing alone, provides adequate disclosure for the genus of oxyanions because, ‘[i]n claims involving chemical materials, generic formulae usually indicate with specificity what the generic claims encompass [and] [a]ccordingly, such a formula is normally an adequate description of the claimed genus.”

The Board disagreed and found Appellant confused the written description requirement of § 112(a) with the enablement requirement of § 112(a).  The Board noted that the enablement requirement was more indulgent than the written description requirement.  The Board acknowledged a specification did not necessarily need to disclose what was well-known and conventional in order to satisfy the enablement prong of § 112(a).  However, the Board emphasized written description and enablement were separate requirements.  In particular, “[a]dequate written description means that the applicant, in the specification, must ‘convey with reasonable clarity to those skilled in the art that, as of the filing date sought, he or she was in possession of the [claimed] invention.’”  The Board further noted a specification must provide some guides or “blaze marks” that disclosed the claimed invention “specifically, as something appellants actually invented.”  The Board did not find Appellant’s argument about whether oxyanions, as a class, were well known to those skilled in the art addressed the separate inquiry of whether the Hassler provisionals provided adequate written description to establish the claim to priority.

Because “one cannot disclose a forest in the original application, and then later pick a tree out of the forest and say here is my invention,” Purdue Pharma L.P. v. Faulding Inc., 230 F.3d 1320, 1326 (Fed. Cir. 2000), the Board did not find Appellant sufficiently demonstrated that any of the earlier filed applications conveyed with reasonable clarity to those skilled in the art that, as of the filing date sought, Appellant was in possession of the claimed Markush species.  Accordingly, the Board held Fischmann constituted prior art.

Takeaway:  To satisfy the written description requirement, a specification must describe the claimed invention in sufficient detail that one skilled in the art can reasonably conclude that the inventor had possession of the claimed invention at the filing date sought.  For a claim to comply with the written description requirement or to be entitled to a priority date, each claim limitation must be expressly or inherently supported in the originally or previously filed disclosure.  When an explicit limitation in a claim is not present, it must be shown that those skilled in the art would have understood that the description requires that limitation.  As illustrated by Hassler, in the chemical art, a structural chemical formula that is not sufficiently detailed fails to show applicant was in possession of the claimed invention as of the filing date sought.

Judges:  T. J. Owens, B. W. Baumeister, and B. D. Range


September 14, 2020by Jacob Doughty

Ex parte Hicks is a 2007 decision of the Board of Patent Appeals and Interferences (BPAI) that is listed among the Patent Trial and Appeal Board’s (PTAB) informative decisions. Ex parte Hicks is indicated by the PTAB to be informative as to “Specification and claim requirements – 35 U.S.C. § 112… Enablement… Indefiniteness… scope.”