Preserving the Patent Bargain: U.S. Supreme Court Limits Amgen’s Monopoly

Preserving the Patent Bargain: U.S. Supreme Court Limits Amgen’s Monopoly

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Amgen Inc. et al. v Sanofi et al, No. 21-757 (Supreme Court May 18, 2023)

On May 18, 2023, the Supreme Court of the United States (“the Supreme Court”) issued a long-awaited decision regarding the scope of the enablement requirement in Section 112 of the Patent Act. In its unanimous decision affirming the Federal Circuit’s ruling, the Supreme Court held that if a patent claims an entire class or genus of processes, machines, manufactures or compositions of matter, the patent’s specification must enable a skilled person to make and use the entire class.


The patents at issue concern antibodies used to reduce levels of low-density lipoprotein (LDL) cholesterol by inhibiting PCSK9, a naturally occurring protein that binds to and degrades LDL receptors.

Amgen and Sanofi each developed a PCSK9-inhibiting drug (Repatha by Amgen, Praluent by Sanofi) that employed a distinct antibody with its own unique amino acid sequence to bind to PCSK9. Each company obtained patents for their unique antibodies. The dispute focused on two continuation patents granted to Amgen (U.S. Patent No. 8,829,165 and U.S. Patent No. 8,859,741).

These continuation patents claimed an entire genus of antibodies that “bind to specific amino acid residues on PCSK9” and “block PCSK9 from binding” to LDL receptors. Amgen identified the amino acid sequences of 26 antibodies that performed these functions. Amgen also described two methods (“the roadmap” and “conservative substitution”) that scientists could use to make additional antibodies that performed the same binding and blocking functions.

After receiving these continuation patents, Amgen sued Sanofi for infringement. Sanofi responded by arguing that the patents were invalid for lack of enablement under section 112(a) of the Patent Act,[1] which states:

The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention. [emphasis added]

Specifically, Sanofi argued that Amgen claimed exclusive use of potentially “millions more antibodies than the company had taught scientists to make”. Amgen only disclosed 26 specific antibodies that fit within the claimed genus, and of those, only disclosed the 3-dimensional structure of 2. Sanofi also argued that the “roadmap” and “conservative substitution” methods described by Amgen for generating additional antibodies were nothing more than a trial-and-error process of discovery.

Both the District Court and the Federal Circuit agreed with Sanofi. The Federal Circuit determined “no reasonable factfinder could conclude” that Amgen had provided “adequate guidance” to make and use the claimed antibodies “beyond the narrow scope of the [26] working examples” identified by amino acid sequence.

Supreme Court Preserves the Patent Bargain

The Supreme Court unanimously affirmed the Court of Appeals for the Federal Circuit, reflecting on the “quid-pro-quo” premise of patent law. The Supreme Court emphasized that:

The patent “bargain” describes the exchange that takes place when an inventor receives a limited term of “protection from competitive exploitation” in exchange for bringing “new designs and technologies into the public domain through disclosure” for the benefit of all. Bonito Boats, Inc. v. Thunder Craft Boats, Inc., 489 U. S. 141, 150. From the Patent Act’s beginnings, Congress has sought to ensure the benefit of this bargain for the public by requiring the patent applicant to deposit a “specification . . . so particular . . . as not only to distinguish the invention or discovery from other things before known and used, but also to enable a workman or other person skilled in the art or manufacture . . . to make, construct, or use the same.” 1 Stat. 110. Over time, Congress has left this “enablement” obligation largely intact.

Relying heavily on the prior Supreme Court decisions of Morse, Incandescent Lamp, and Holland Furniture, the Supreme Court held that “if a patent claims an entire class of processes, machines, manufactures, or compositions of matter, the patent’s specification must enable a person skilled in the art to make and use the entire class. In other words, the specification must enable the full scope of the invention as defined by its claims. The more one claims, the more one must enable”.

The Supreme Court did recognize that this does not require a specification to describe how to make and use every single embodiment within a claimed class, nor was a specification inadequate simply because the skilled person engaged in some measure of adaptation or testing. A reasonable amount of experimentation would depend on the nature of the invention and the underlying art. However, the Supreme Court cautioned that in allowing such tolerance, “courts cannot detract from the basic statutory requirement”.

In this case, the Supreme Court found that Amgen had failed to enable all that it had claimed, even with the allowance of a reasonable degree of experimentation. Amgen sought to monopolize an entire class of antibodies, which included not just the 26 that Amgen had sequenced, but a “vast number of additional antibodies” that it had not. Amgen tried to argue that its broad claims were enabled because scientists could make and use every undisclosed antibody by following the “roadmap” or “conservative substitution” methods, but this argument was rejected. The Supreme Court found that scientists would be “forced to engage in painstaking experimentation to see what works”, which was an uncertain prospect given the state of the art.


This decision notably highlights the patent bargain, a theory frequently used by the Canadian Supreme Court as the bedrock of Canadian patent law. If properly understood within the context of an exception to antitrust law, nearly all principles of patent law (novelty, obviousness, utility, enablement, etc.) can be derived from this theory. Though the US Supreme Court has previously mentioned this theory, it often leans towards other approaches rather than tying issues directly to the patent bargain. However, the US court’s endorsement of the bargain theory in this case suggests alignment between Canadian and US patent laws, strengthening the usability of this framework for analyzing patent issues. Despite potential criticisms, the bargain theory’s power lies in its ability to yield predictable results.

For more information on enforcing patents in the U.S., please contact a patent lawyer at PCK Intellectual Property.


[1] 35 U.S.C. §112(a).

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