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On May 18, 2023, the Supreme Court of the United States issued a unanimous decision in the case of Amgen Inc. et al. v. Sanofi, et al., No. 21-757. After a nine-year saga, beginning when Amgen sued Sanofi for allegedly infringing two of its patents in 2014, the Supreme Court held that Amgen’s asserted patents failed to satisfy the enablement requirement under 35 U.S.C. § 112(a), and are thus invalid.


Section 112(a) of the Patent Act requires that a patent specification includes “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 make and use the same. This has been interpreted to require that the specification includes enough disclosure to enable any person skilled in the art to make and use the invention without “undue experimentation.” In re Wands, 858 F.2d at 737, 8 USPQ2d at 1404 (Fed. Cir. 1988).

Amgen’s Patents

Amgen’s asserted patents relate to antibodies for PCSK9, which is involved in LDL cholesterol metabolism. The asserted claims purportedly cover the entire genus of antibodies that 1) bind to certain residues of the PCSK9, and 2) block binding of PCSK9 to LDL receptor (LDLR) – defining antibodies by functional limitations, not by structure. 

Not Enabling

Sanofi asserted the claims are invalid because Amgen disclosed only 26 exemplary antibodies, which it identified by their amino acid sequences, and this does not enable a person skilled in the art to make and use all of the potentially millions of antibodies that perform these two functions. In response, Amgen argued that its patents were enabled because they disclosed a method for generating these antibodies having the same function.

Both the District Court and the Federal Circuit had sided with Sanofi, with the Federal Circuit determining that “no reasonable factfinder could conclude” that Amgen provided “adequate guidance” to make and use the claimed antibodies “beyond the narrow scope of the [26] working examples” identified by their amino acid sequences. The Supreme Court affirmed, stating “Amgen has failed to enable all that it has claimed, even allowing for a reasonable degree of experimentation.”

The Supreme Court explained that a specification may call for a reasonable amount of experimentation to make and use a patented invention, or that it may call for the skilled artisan to engage in some measure of adaptation or testing. But they further explained that “[w]hat is reasonable in any case will depend on the nature of the invention and the underlying art.”

The Supreme Court noted that Amgen seeks to “monopolize an entire class of things defined by their function,” while this class of antibodies includes a “vast” number of antibodies that Amgen has not described in the specification.

In response to Amgen’s argument that its broad claims are enabled because the patent specifications provided a “roadmap” to make the other antibodies, the Supreme Court stated that the guidance provided in the specification leaves a scientist to engage in “painstaking experimentation” to see what works.

Amgen also asserted that that Federal Circuit erroneously applied higher standard to Amgen’s claims that encompass an entire genus of embodiments defined by their function. The Supreme Court responded that Federal Circuit correctly applied statutory enablement standard – “the more a party claims for itself the more it must enable,” which reflect Congress’s judgment that if an inventor claims a lot, but enables only a little, the public does not receive its benefit of the bargain. The Supreme Court further noted that Amgen’s specifications offered the POSITA little more than advice to engage in trial and error.


The decision underscores the importance of the enablement requirement, and will make it more difficult for patent holders to obtain broad protection covering entire classes of materials without sufficient disclosure.

Patent applicants should understand the importance of including sufficient examples, direction, and guidance in the specification, especially where complex subject matter is claimed. While it may be a practical impossibility to disclose millions of species, providing more concrete guidance on how the POSITA may arrive at those different possibilities may take your disclosure out of the realm of providing only “trial and error” or a “hunting expedition” and into the realm of enablement.