Supreme Court Reaffirms Enablement Standard

  • May 19, 2023
  • Category: Patent Litigation Feature

The US Supreme Court has doubled down on its existing approach to enablement, the requirement that a patent must describe an invention “in such full, clear, concise, and exact terms” that a person having ordinary skill in the art (PHOSITA) can “make and use” it. In Amgen v. Sanofi, the Court agreed with the Federal Circuit and the District of Delaware that claims from two antibody patents related to a cholesterol-lowering drug were invalid on this basis. While the claims encompassed an entire genus of possible antibodies, the Court concluded in a unanimous opinion that the patent required too much experimentation by a PHOSITA to recreate the antibodies described in the patents—rejecting both of the described approaches for doing so as “little more than two research assignments”.

The enablement requirement, as reflected in 35 USC Section 112(a), forms a key part of the “bargain” offered by the patent system. In exchange for a limited-term monopoly on his or her invention, the inventor must sufficiently describe the invention so that others may benefit from and practice the claimed technology once it passes into the public domain.

As noted above, the technology here at issue concerns antibodies, which the immune system produces in order to bind to antigens (foreign agents) like viruses, thereby preventing them from causing harm to the body. An antibody’s function is dictated in large part by its amino acid sequence and the “complex three-dimensional shapes” that form when the amino acids’ atoms interact with one another. To bind to a targeted molecule, the antigen must have a structure that, based on both its amino acid sequence and three-dimensional shape, allows it to “establish a sufficiently broad, strong, and stable bond” to that molecule.  

The Amgen patents here at issue (8,829,165 and 8,859,741) relate to an engineered antibody designed not to target external invaders but one of the body’s own proteins—here, one called PCSK9, which binds to and degrades the function of the LDL receptors that the body uses to break down harmful LDL cholesterol. The company implemented the technology claimed in an earlier, related patent in its drug Repatha, which includes an antibody that binds to PCSK9 at a certain “sweet spot” that prevents it from blocking LDL receptors, while its competitor Sanofi obtained its own patent for a different antibody used in its own PCSK9-inhibiting drug, Praluent.

As later recounted by the Supreme Court, Amgen “did not seek protection for any particular antibody described by amino acid sequence” in the asserted claims, but instead “purported to claim for itself ‘the entire genus’ of antibodies that (1) ‘bind to specific amino acid residues on PCSK9,’ and (2) ‘block PCSK9 from binding to [LDL receptors]’”. The patents disclose the amino acid sequences for 26 antibodies that perform these functions, further depicting the three-dimensional structures for two of them. Importantly, the patents describe two approaches for creating antibodies with the same functions. The first, called the “roadmap” method, requires scientists to create a “range of possible antibodies” in a lab; test whether they bond to the PCSK9 protein, in particular to the required “sweet spot”; and whether those antibodies then block the protein from bonding to LDL receptors. The second, called the “conservative substitution method”, directs scientists to start with an existing “antibody known to perform the described functions”, replace certain amino acids with others known to have the same “properties”, and “test the resulting antibody to see if it also performs the described functions”.

Amgen subsequently sued Sanofi for infringement, asserting the ’165 and ’741 patents along with five others. The litigation twice made its way to the Federal Circuit, first over a verdict that the patents-in-suit were not invalid for lack of enablement and lack of an adequate written description. The Federal Circuit overturned that verdict and remanded for a new trial, identifying errors in the district court’s evidentiary rulings and jury instructions on those issues. A second jury then reached the same conclusions, after which Sanofi moved for motion for judgment as a matter of law (JMOL) of invalidity for lack of enablement, “observ[ing] that Amgen’s claims cover potentially millions more undisclosed antibodies that perform these same functions” (as summarized by the Supreme Court). It argued that “neither of the two methods Amgen had outlined for generating additional antibodies with the same functions enable a person skilled in the art to do so reliably”, and instead “require scientists to engage in little more than a trial-and-error process of discovery”.

The district court then granted JMOL for Sanofi, agreeing that the patents are “not enabled”. On appeal once again, the Federal Circuit affirmed in February 2021, determining that “‘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’ it had identified by their amino acid sequences”. The court denied Amgen’s petition for a panel and en banc rehearing that same June after receiving amicus briefs from a variety of other pharmaceutical companies (including Biogen, Bristol-Myers Squibb, GlaxoSmithKline, and Merck Sharp & Dohme) and a group of law professors.

Amgen filed a petition for writ of certiorari in November 2021. In April 2022, the court issued a call for the views of the US Solicitor General, Elizabeth Prelogar, on behalf of the US government. That brief urged the Court not to review the case, arguing that Amgen was wrong to assert that the lower courts had “usurped” the role of the jury and was wrong on the law with respect to enablement. However, somewhat unusually, the Court granted certiorari despite that recommendation in November 2022.

In a unanimous opinion issued on May 18 and authored by Justice Neil Gorsuch, the Court began by underscoring the role that the enablement standard plays in the patent “bargain”. The Court observed that this requirement has survived “largely intact” since the Patent Act of 1790 even though legislative reform has since reshaped other areas of patent law. Given that lengthy history, the Court then analogized the present case to a variety of enablement decisions from throughout its history, as far back as the 19th Century—arguing that “[w]hile the technologies in these older cases may seem a world away from the antibody treatments of today, the decisions are no less instructive for it”.

Among those older but still “instructive” decisions was O’Reilly v. Morse (1854), in which the Court invalidated one claim from a telegraph patent naming famed inventor Samuel Morse. While the opinion upheld claims related to “telegraphic structures and systems” he had designed, it reached the opposite conclusion for a claim covering “the use of the motive power of the electric or galvanic current . . . however developed for marking or printing intelligible characters, signs, or letters, at any distances”. The Court invalidated this claim as lacking enablement because it essentially covered “all means of telegraphic communication” but did “not describe[] how to make and use them all” (quoting Amgen).

In 1895, the Court’s Incandescent Lamp Patent decision reached a similar conclusion for a patent naming two inventors who had unsuccessfully sought to use carbonized paper as a light bulb filament. Their patent covered not only the use of such paper, but also “made a broad claim for every fibrous and textile material”. The Court held that the patent was invalid for lack of enablement because the inventors had failed to identify a common “quality” that would enable the selection of suitable materials; to the contrary, the bamboo filament used successfully by defendant Thomas Edison had only been arrived at through “painstaking experimentation”. In 1928, the Court made much the same determination in its Holland Furniture v. Perkins Glue decision for a patent describing a starch glue that mimics the qualities of animal glue. That patent covered the use of any “starch glue” as mixed with certain proportions of water and alkali, but its “specification described the key input—the ‘starch ingredient’—in terms of its ‘use or function’ rather than its ‘physical characteristics or chemical properties’”. The Court determined that the “elaborate experimentation” required to identify an appropriate “starch ingredient” meant that the patent also lacked proper enablement.

Overall, the Court explained, those three decisions “reinforce the simple statutory command” that “[i]f 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”.

That said, the Court also acknowledged that a specification does not always need to “describe with particularity how to make and use every single embodiment within a claimed class”. For example, a patent that describes a “general quality” common to the covered class that gives it “a peculiar fitness for the particular purpose”, as found lacking in Incandescent Lamp, might “reliably enable” a PHOSITA to make and use everything claimed.

Nor, for that matter, does a specification necessarily lack enablement because it requires the “skilled artist to engage in some measure of adaptation or testing”, the Court further held. To illustrate the extent that this may be permissible, the Court invoked two more decisions: In Wood v. Underhill (1846), it upheld a patent claiming “a process for making bricks by mixing coal dust into clay” that “included ‘a general rule’ about the proportion of dust and clay to use and offered two alternative proportions ‘where the clay has some peculiarity’”. The Court found that this was sufficient since different varieties of clay might occasionally require “some small difference in the proportions” needed. Another patent related to separating metal from mineral ores survived an enablement challenge in Minerals Separation v. Hyde (1916), with the Court underscoring that the required certainty did not exceed that which is “reasonable”. It determined that a requirement that “preliminary tests” be conducted to adapt the process for different ores was reasonable since the “composition of ores varies infinitely”, which would make it impossible to specify the “precise treatment” for each one. In short, the Court held in Amgen, “[d]ecisions such as Wood and Minerals Separation establish that a specification may call for a reasonable amount of experimentation to make and use a patented invention”, with what is reasonable “depend[ing] on the nature of the invention and the underlying art”.

Turning to the two Amgen patents here at issue, the Court found that while they adequately describe the 26 antibodies explicitly specified, it “agree[d] with the lower courts that Amgen has failed to enable all that it has claimed, even allowing for a reasonable degree of experimentation”. The Court determined that at their core, the patents—despite the relative modernity of the claimed technology—“bear more than a passing resemblance to those this Court faced long ago in Morse, Incandescent Lamp, and Holland Furniture”. Since the Amgen patents, like the ones from those older cases, “seek[] to monopolize an entire class of things defined by their function”, here including the “vast” number of antibodies not explicitly disclosed, it faced a “challenge”: “[T]he more a party claims, the broader the monopoly it demands, the more it must enable”, which holds true whether the technology “involves telegraphs devised in the 19th century, glues invented in the 20th, or antibody treatments developed in the 21st”.

While Amgen acknowledged this in its appeal, the company also argued that the “roadmap” or “conservative substitution” approaches allow scientists to “make and use every undisclosed but functional antibody”. The Court countered that it “cannot agree”, rejecting the first one as the same “trial and error” method Amgen had used to develop the technology in the first instance, finding that “conservative substitution” was not “much different”. Amgen’s patents failed to disclose a “quality common to every functional embodiment”, instead “forc[ing scientists] to engage in ‘painstaking experimentation’ to see what works”. The Court underscored, “[t]hat is not enablement. More nearly, it is ‘a hunting license’” (citing its 1966 Brenner v. Manson decision).

Here, the court found an analogy from several law professor amici to be persuasive: The roadmap approach, in particular, is akin to a combination lock with 100 tumblers that each has 20 different positions, where a patent discloses 26 successful combinations but claims all possible combinations. A requirement to try and record successful combinations would “not enable others to make and use functional combinations”, but would instead merely amount to “random trial-and-error discovery”.

Having thus determined that Amgen’s primary enablement arguments failed, the Court then proceeded to reject its two alternative arguments alleging errors in law by the Federal Circuit. The Court disagreed that the Federal Circuit had “erred by applying an enablement test unmoored from the statutory text”, indicating instead that the patent owner was mischaracterizing the Federal Circuit’s position: That appellate court was not contending that enablement should be measured “against the cumulative time and effort it takes to make every embodiment within a claim”. Rather, the Federal Circuit was identifying the same problem as the Supreme Court: that Amgen was offering “little more than advice to engage in ‘trial and error’”. Nor did the Court agree that the Federal Circuit had “‘erroneously “raise[d] the bar’ for enablement of claims that, like Amgen’s, encompass an entire ‘genus’ of embodiments defined by their function”. The Court did not understand the Federal Circuit to have departed from the notion that there is a single, universal enablement standard—it was merely ruling “that the more a party claims for itself the more it must enable”, a position that “is entirely consistent with Congress’s directive and this Court’s precedents”.

The Supreme Court also rejected Amgen’s argument that affirming the Federal Circuit would “destroy incentives for breakthrough innovations”:

But striking the proper balance between incentivizing inventors and ensuring the public receives the full benefit of their innovations is a policy judgment that belongs to Congress. Since 1790, Congress has included an enablement mandate as one feature among many designed to achieve the balance it wishes. Our only duty in this case lies in applying that mandate faithfully.

The Court then ended by tying Congress’s judgment, as expressed in Section 112, back to the key, underlying role that enablement plays in patent policy: “that if an inventor claims a lot, but enables only a little, the public does not receive its benefit of the bargain”. That same notion has guided the Court’s decisions for 150 years, it concluded: “Today’s case may involve a new technology, but the legal principle is the same”.


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