Guest Column | July 10, 2023

Patenting Functionally Claimed Biological Compounds After Amgen V. Sanofi

By Jonathan B. (J.B.) Fitzgerald, Ph.D., and Trent L. Hoffman

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In Amgen v. Sanofi, on May 18, 2023, the Supreme Court upheld the Federal Circuit’s holding that Amgen’s patent claims for functionally claimed antibodies were invalid for failing to meet the enablement requirement.1 The Court’s ruling in Amgen has set a high bar for enabling functionally claimed biological compounds. This article will (i) review the Supreme Court’s patent enablement standard as described in Amgen, (ii) discuss the Supreme Court’s application of its enablement standard to the patent claims at issue in the Amgen case, (iii) describe potential complexities of analogizing antibodies to the technologies described in the precedents used by the Amgen court, and (iv) analyze the potential susceptibility of functionally claimed biological compounds to invalidity challenges after the Amgen case.

The Supreme Court Upholds The “Full Scope” Enablement Test

The Supreme Court upheld the Federal Circuit’s “full scope” enablement test. Specifically, the Court stated that “If a patent claims an entire class of processes…or compositions of matter, the patent’s specification must enable a person skilled in the art to make and use the entire class.” This is similar to the Federal Circuit’s position on this same case in which it concluded that when claims include functional requirements, the proper focus is on the breadth of the functional requirements and the quantity of experimentation that would be required to make and use the full scope of the functional requirements.2

In support of upholding the “full scope” enablement test, the Court relied on three previous Supreme Court cases in which the enablement requirement was addressed: (i) O’Reilly v. Morse3 (Morse); (ii) The Incandescent Lamp Patent(Incandescent Lamp); and (iii) Holland Furniture Co. v. Perkins Glue Co5 (Holland Furniture).  In each of these cases, the Court invalidated broad functional patent claims based on its findings that the full scope of the claims was not enabled. 

In Morse, the technology at issue was an electromagnetic telegraph. The Court upheld claims that recited features related to the telegraphic structures and features that Morse had designed. However, the Court invalidated a claim that referred broadly to using any type of electric or galvanic current to achieve telegraphic communication. More specifically, the Court noted, “[Morse] claims an exclusive right to use a manner and process which he has not described and indeed had not invented, and therefore could not describe when he obtained his patent.” The issue with Morse’s patent claim, the Court describes, is “that the claim covered all means of achieving telegraphic communication,” but the specification did not describe how to make and use them all.

In Incandescent Lamp, the technology at issue was an incandescing conductor for an electric lamp. With the exception of one claim that described the structure of the incandescing conductor as “formed of carbonized paper,” the Court found the remaining claims to be invalid.  In particular, the Court found that a claim for an incandescing conductor “of carbonized fibrous or textile material” was too broad because the patent did not disclose a common quality running through the class of "carbonized fibrous or textile material” that adapted them peculiarly to incandescent conductors. Notably, the specification only provided limited examples of carbonized fibrous or textile material, which was deemed insufficient to support the claims.

In Holland Furniture, the technology at issue was a starch glue for wood veneering that performed as well as animal glue. The patentee in Holland Furniture attempted to claim a glue “having substantially the properties of animal glue.” The Supreme Court noted that, rather than describe its glue in terms of its composition or structure, the claims described the glue in terms of the use or function. The Court held that the patentee was only entitled to patent the specific starch glue that had been invented, which included glue’s characteristic ingredients. The Court concluded that “[o]ne attempting to use or avoid the use of [the patentee’s] discovery as so claimed and described functionally could do so only after elaborate experimentation.”

Thus, the Supreme Court reasoned that the patentees in Morse, Incandescent Lamp, and Holland Furniture did not enable all means of telegraphic communication, all carbonized fibrous or textile materials for incandescence, and all starch glues that performed as well as animal glue, respectively. As a result, the broad, functional processes and compounds claimed in these cases were held invalid. According to the Amgen court, these cases support the proposition that the “full scope” of the claimed invention must be enabled. 

Despite upholding the “full scope” enablement test, the Supreme Court stated in Amgen that not all embodiments of a claimed class must be described if the specification describes “some general quality…running through” the claimed class. In addition, the Court referenced the Supreme Court case Wood v. Underhill6 (Wood) to show that some level of testing is permissible. Notably, in Wood, a case involving a patent related to a process of mixing coal dust into clay to make bricks, the Court upheld a claim that did not specify the specific proportions of dust and clay that must be used. The Court reasoned that because the composition of ores has infinite variation, it would be impossible for the patent to describe the best treatment. Accordingly, the Court concluded that even though preliminary tests were required to adapt the claimed process to the particular ores that were used, the claims were still valid.   

The Supreme Court’s Application Of The Full Scope Enablement Test To Amgen’s Antibody Claims

Amgen owned the patents in suit, which claimed antibodies that were defined by two functions: (1) the ability to bind specific residues on an enzyme and (2) the ability to block binding of that enzyme to a receptor. Thus, Amgen claimed its antibodies according to their dual functions of (1) and (2). In an effort to support these functional claims, Amgen disclosed 26 exemplary antibodies that carried out both functions (1) and (2) and described a method for screening antibodies that can be used to identify additional antibodies that can carry out functions (1) and (2). 

According to the Supreme Court, these disclosures were insufficient to satisfy the enablement requirement. In particular, the Court noted that there are millions of candidate antibodies beyond the 26 disclosed antibodies that may carry out functions (1) and (2). Additionally, according to the Court, the screening method that Amgen disclosed was nothing more than a research assignment in which candidate antibodies were screened and potentially mutated to determine whether they carry out the dual functions recited in the claims. The Court characterized the screening method as a “hunting license” that would result in “painstaking experimentation.”

The Supreme Court analogized Amgen’s claims to those that were invalidated in Morse, Incandescent Lamp, and Holland Furniture. Specifically, the Court stated that similar to the patentees in Morse that tried to claim all forms of telegraphic communication, Incandescent Lamp that tried to claim all fibrous and textile materials for incandescence, and Holland Furniture that tried to claim all starch glues that work as well as animal glue, Amgen sought to claim “sovereignty over an entire kingdom of antibodies” that it had not enabled. As a result, the Court found that Amgen’s functionally defined antibodies were invalid under the enablement standard.

The Complexity Of Analogizing Antibodies To The Technologies Described In The Precedents Used By The Amgen Court

The Supreme Court made it clear that Amgen’s disclosure of 26 antibodies and its description of how to identify additional antibodies that fall within the scope of the claims was insufficient to satisfy the enablement requirement. What seems to be unclear from the Amgen case, is what Amgen needed to disclose to satisfy the enablement requirement. 

This seeming lack of clarity derives in part from the precedential cases (Morse, Incandescent Lamp, and Holland Furniture) upon which the Supreme Court relied to uphold the “full scope” enablement test: none of these cases involve functionally claimed biological compositions. For companies and inventors that are developing biological compositions such as therapeutic antibodies, it might be difficult (if not impossible) to take cues from telegraph (Morse), incandescence (Incandescent Lamp), and starch glue (Holland Furniture) patents to determine how to enable their biological inventions.

Moreover, the Wood case that the Supreme Court cited as establishing that some experimentation is permitted arguably means that Amgen’s dual functional antibody claims should have satisfied the enablement requirement. In Wood, the Court upheld a claim that recited “where the clay has some particularity” on the basis that ores have infinite variation. The Court found that even though preliminary testing was needed to adapt a process to a particular ore, the claim was still enabled. In its comments regarding this issue of the variability of ores, the Court stated that the law does not require certainty that is greater than reasonable. This reasoning in Wood could be analogized to antibodies. For example, like ores, antibodies also have infinite variation. Accordingly, although preliminary testing (screening) would also be needed to determine which antibodies fall within the functionally claimed class, the patent claims could still be enabled. 

Thus, the Amgen court, relying on the precedent in the Wood court, could have found that Amgen’s disclosure of 26 antibodies and disclosure of a screening method for identifying additional antibodies were sufficient to meet the enablement requirement. Similarly, as the Court reasoned in Wood, the Amgen court could have concluded that to require more than these disclosures would be unreasonable under the law, in view of the infinite variability of antibodies. But, the Court found the opposite. 

Perhaps the difficulty in analogizing Morse, Incandescent Lamp, Holland Furniture, and Wood to the antibodies lies in the nature and complexity of the technologies in these cases. For example, the complexity of creating bricks is arguably quite low relative to the complexity of synthesizing antibodies that can elicit a therapeutic effect (which is arguably very high). The Wood court reasoned that the testing required for adapting the claimed process to a particular ore was acceptable under the enablement standard. However, it is unclear how this standard in Wood would apply to a much more complex process of screening and testing antibodies that is described in Amgen’s patent. As such, while the Wood case provides one precedential example of permissible experimentation under the enablement standard, this standard may have limited applicability to pharmaceutical companies and inventors that are developing biological compounds of arguably much greater complexity than the ores at issue in the Wood case.

The Potential Susceptibility To Invalidity Challenges For Functionally Claimed Biological Compounds After Amgen V. Sanofi

In Amgen, the Supreme Court upheld a stringent standard for enabling functionally claimed biological compositions in which the “full scope” of the claims must be enabled. As the Supreme Court stated, if an entire class of compositions is claimed, the specification must enable a person of skill to make and use the entire class. The Court does permit a certain level of experimentation under the enablement standard but has not clarified what level of experimentation would be permitted for functionally claimed biological compounds. Thus, the Supreme Court’s ruling in Amgen sets a high and uncertain bar to enable functionally claimed biological compounds. 

The Court’s ruling in Amgen can be analyzed in conjunction with Federal Circuit’s holding in Juno v. Kite7 (Juno), which the Supreme Court declined to review. At issue in Juno was the standard for showing that functionally claimed biological compounds have met the written description requirement. In Juno, the Federal Circuit held that functionally biological compounds must show possession of the entire claimed class (i.e., the “full scope” of the claimed class) to satisfy the written description standard (see, this previous article and this previous article). Thus, under Amgen and Juno, the full scope of functionally claimed biological compounds must be both enabled and described in the patent specification. 

After the Amgen and Juno holdings, the burden to show that functionally claimed biological compounds have met the enablement and written description standards appears to be heightened. As such, a number of patents directed to functionally claimed biological compounds may be susceptible to invalidity findings under one or both of these standards.


  1. No. 21-757 (2023).
  2. No. 2020-1074 (Fed. Cir. 2021).
  3. 56 U.S. 62 (1853).
  4. 159 U.S. 465 (1895).
  5. 277 U.S. 245 (1928).
  6. 46 U.S. 1 (1847).
  7. No. 2020-1758 (Fed. Cir. 2021).

About The Authors:

Jonathan B. (J.B.) Fitzgerald, Ph.D., is counsel at Snell & Wilmer. He is a registered patent attorney and has a Ph.D. in molecular physiology. His primary practice area involves preparing and prosecuting patent applications in the biotechnology and the life sciences.

Trent Hoffman is an associate in Snell & Wilmer’s intellectual property practice group. His practice is concentrated in intellectual property law, including patent and trademark prosecution, strategic intellectual property counseling, and trademark dispute resolution. He may be reached at