Written by: Tanner Murphy

A nearly decade-long patent infringement clash between two pharmaceutical heavyweights reached its apogee on March 27, 2023, when the Supreme Court heard the two parties (and the government) argue an issue that will have wide-reaching impact on technology protections: the Patent Act’s enablement requirement, particularly as applied to functional genus claims.

Amgen and Sanofi’s Infringement Lawsuits

In 2014, biopharmaceutical firm Amgen, Inc. filed a patent infringement lawsuit against a French competitor, Sanofi. Amgen alleged that Sanofi’s cholesterol drug Praluent infringed Amgen patents covering antibodies that bind to certain sites on PCSK9 (an enzyme in human blood) and block the interaction between PCSK9 and low-density lipoprotein (LDL) receptors, purportedly lowering LDL cholesterol levels. In 2016, a jury ruled in Amgen’s favor. Sanofi appealed, and the Federal Circuit remanded the case for a retrial on whether the patents lack sufficient written description or enablement, as required by 35 U.S.C. § 112. On remand, a jury again found that Sanofi failed to prove that the patents lacked sufficient written description or enablement. Sanofi moved the district court for judgment notwithstanding the verdict and prevailed: the trial court held that the patent claims were not enabled by their specification. Amgen appealed, and the Federal Circuit affirmed the district court’s decision in 2021.

Sanofi successfully petitioned the Supreme Court to hear the case to determine whether the patent claims are enabled by the patent’s specification. That question requires a clarification or application of the appropriate legal standard for § 112’s “enablement” requirement—a determination that will impact the entire patent law landscape.

The Statutory Enablement Requirement

The Patent Act requires a patent’s specification to contain a written description of both the invention “and of the manner and process of making and using it” sufficient “to enable any person skilled in the art” to which the invention pertains to “make and use” the invention.¹ This so-called “enablement” requirement enforces the “quid pro quo of the patent bargain” by requiring a patentee to teach the public how to practice the claimed invention in exchange for market exclusivity for a defined period of time.²

The Federal Circuit Test

The Federal Circuit’s current test for determining whether a patent satisfies the enablement requirement focuses on whether a patent’s specification enables the “full scope” of the invention to be practiced without “undue experimentation” (language that is not literally present in 35 U.S.C. § 112).³ To answer that question, courts apply a factor test (the Wands factors).⁴

Amgen’s Patents

Amgen’s patents claim antibodies that bind to PCSK9 as a means of regulating cholesterol. PCSK9 is a protein that binds to and degrades certain receptors in the body that would otherwise remove cholesterol from the blood stream. Certain antibodies, however, may bind and block PCSK9, thus allowing the aforementioned receptors to continue regulating cholesterol. Amgen did not claim specific antibodies in its patent, but instead claimed a class of “antibodies” generally that perform this function. That is often referred to as a “functional genus” claim.

The Question Before the Supreme Court

The Court is tasked with determining whether the Federal Circuit’s enablement test is consistent with its statutory basis: 35 U.S.C. § 112(a). Petitioner Amgen presents the question as “whether enablement is governed by the statutory requirement that the specification teach those skilled in the art to ‘make and use’ the claimed invention (35 U.S.C. §112), or whether it must instead enable those skilled in the art to reach the ‘full scope’ of claimed embodiments without ‘undue experimentation.’⁵


Amgen argues that that the Federal Circuit’s “full scope” test departs from the statutory “make and use” requirement and is too demanding. According to Amgen, the “full scope” test requires the patent’s specification to teach how to make and use every conceivable embodiment of the invention, regardless of how remote or hypothetical the embodiment may be—which departs from the statutory text of the 35 U.S.C. § 112.⁶ Amgen points out that such a broad description requirement would be impossible to satisfy in many cases that all agree are patentable: “There may be myriad variations on James Watt’s steam engine or the Wright Brothers’ airplane. But the law has never required that, for those inventions to be patentable, skilled artisans must be able to cumulatively identify and make every variation without substantial time and effort.”⁷ Doing that would be impossible.⁸  

Sanofi,⁹ on the other hand, says that Amgen “is attacking a straw man” by adding its own language to the Federal Circuit’s decision to argue that its test turns on the effort required to “cumulatively identify and make all or nearly all embodiments of the invention.”¹⁰ According to Sanofi, the Federal Circuit was clear that its test did not turn on the cumulative efforts required to make and use all embodiments—even in a functional genus. But the Federal Circuit’s test does take those efforts into account as a factor, especially when claims are very broad—as in a function genus claim. Sanofi also argues that Amgen’s proposed test asks too little of a patentee: that it only explain how to put the invention to practice in some way. Amgen’s patents, Sanofi argues, tells skilled artisans “little they did not already know, instructing them to make claimed antibodies by randomly generating and testing candidates.”¹¹ Sanofi also argues that “functional genus claims are terrible,” and used as an example the eighth claim in a Samuel Morse patent that purported to claim anything that allows letters to print electronically at a separate location. But that is distinguishable here: according to Amgen, its patents give a “how to” roadmap that it claims allows anyone in the art with ordinary access to common machines to produce a claimed antibody every time. The Morse claim is far less instructive about how to make the invention, or what the invention really is in any embodiment.

The Supreme Court’s questioning focused heavily on the facts that Amgen’s patent identified 26 claimed antibodies structurally and it disclosed that 384 were produced by their disclosed “roadmap” for creating the claimed antibodies, but that there may be a million or more antibodies within the claim that can be produced by doing “conservative substitution” or other processes. The argument illuminated some of the tensions that the Court may need to resolve. Of those, one salient is whether (and how) § 112(a)’s “make and use” should have a distinct test for functional genus claims. After all, it is a relatively simple question to know whether a specific invented antibody can be made and used from the patent’s disclosure. But it is more difficult to know whether the described manner and process permits one skilled in the art to “make and use” a genus of antibodies defined by a specific function.

The Future of Genus Claims

A blanket rule by the Supreme Court specific to functional genus claims could have profound consequences. If the Court requires the patent to describe how to make all variants within the genus, then the fallout may be galactic. That seems unlikely because both parties, the government, and the Court seemed to agree that § 112(a) does not require one to enable every conceivable embodiment. But even short of that, a categorical enablement test for functional genus claims could fundamentally change what functional genus claims are patentable.

We will watch expectantly (along with everyone else) for a decision—and we will report more then.

1. 35 U.S.C. 112(a).

2. McRO, Inc., v. Bandai Namco Games America Inc., 959 F.3d 1091, 1100 (Fed. Cir. 2020).

3. Id.

4. In re Wands, 858 F.2d 731 (Fed. Cir. 1988).

5. Brief for Petitioners at (i), Amgen v. Sanofi (Dec. 27, 2022) (No. 21-757).

6. Id.

7. Id.

8. Amgen’s supporters include several biotech and pharmaceutical heavyweights (such as Abbvie, Biogen, Bristol Myers, Merck, and GlaxoSmithKline), all of which have filed amicus briefs urging the Supreme Court to do away with “full scope” test.

9. Like Amgen, Sanofi also found support from major names in pharmaceuticals (like Pfizer and Eli Lily), which filed amicus briefs supporting Sanofi.

10. Brief for Respondents at 20, Amgen v. Sanofi (Feb. 3, 2023) (No. 21-757).

11. Id. at 3.