Amgen Inc. v. Sanofi
The Supreme Court unanimously struck down Amgen's sweeping patents on a class of cholesterol-fighting antibodies, ruling that Amgen had claimed exclusive rights over millions of compounds it had never actually taught anyone to make.
The decision reinforces a foundational rule of patent law: the broader the monopoly a company demands, the more completely it must explain how to create everything it claims to own.
How it got here: A federal district court found Amgen's broad patent claims invalid; the Federal Circuit affirmed; Amgen asked the Supreme Court to step in and the Court agreed to hear the case.
The Case in Depth
What happened
Amgen and Sanofi each developed antibody-based drugs to treat dangerously high LDL ("bad") cholesterol by blocking a protein called PCSK9 that degrades the body's natural cholesterol-clearing mechanism. Beyond patenting their own specific antibodies, Amgen also sought two broad patents claiming exclusive ownership over every antibody — potentially millions — that performs those same two blocking functions, even though Amgen had only fully described 26 specific antibodies by their chemical sequences.
The question before the Court
Can a drug company patent an entire class of potentially millions of antibodies by describing only what they do — without teaching scientists how to make most of them?
The Court's answer
No — the Court ruled that Amgen's broad patents were invalid because they failed the Patent Act's "enablement" requirement, which demands that a patent teach anyone skilled in the relevant field how to make and use the full scope of what the patent claims to own. Amgen claimed rights over an enormous functional class of antibodies — potentially millions — but described only 26 by their specific amino acid sequences and offered two methods for finding others.
Those two methods, which Amgen called the "roadmap" and "conservative substitution," amounted to little more than research assignments: generate lots of candidate antibodies and test them to see which work, or swap out amino acids in known antibodies and test the results. Because the science of predicting antibody behavior from chemical sequence remains poorly understood, both methods leave scientists to open-ended trial and error rather than genuine enabling guidance. A patent that claims an entire kingdom of compounds but teaches scientists only how to go hunting cannot stand.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Drug companies and biotech firms seeking broad patents that cover entire categories of compounds defined by what they do — rather than their specific chemical makeup — must now provide far more detailed disclosure to secure those rights. Patents describing particular molecules by their exact structure remain valid; sweeping functional claims that outrun the inventor's actual teaching face invalidation, which will shape how pharmaceutical companies draft and defend future patent applications.
What changes now
Amgen's two broad functional patents are invalid, and Sanofi's Praluent drug is no longer threatened by them. Amgen retains its earlier, narrower 2011 patent covering the specific antibody in its own Repatha drug, which was not at issue here. Going forward, pharmaceutical and biotech companies will need to provide far more complete chemical or structural disclosure — or identify a quality common to every functional variant — before courts will uphold broad genus patents like the ones Amgen pursued.
What this does not decide
The Court does not decide what Amgen would have needed to do to obtain a valid broad patent — for example, whether identifying a quality common to all functional antibodies in the class would have been enough. The ruling also does not address Amgen's separate, narrower 2011 patent on the specific antibody in Repatha, which was never challenged in this case.
How the Court got there
The legal reasoning, step by step
- The Patent Act's enablement requirement (35 U.S.C. § 112(a)) is the core of the patent bargain: in exchange for a time-limited monopoly, an inventor must disclose the invention 'in such full, clear, concise, and exact terms as to enable any person skilled in the art to make and use' it. This requirement has been part of U.S. patent law since 1790 and is Congress's way of ensuring the public ultimately benefits from inventions once patents expire.
- The Court drew on three of its own older decisions to establish the governing principle. In O'Reilly v. Morse, it struck down a claim to all means of telegraphic communication because Morse only described some of them. In The Incandescent Lamp Patent, it rejected a claim covering every fibrous or textile material for incandescent lighting because the inventors had only figured out carbonized paper and hadn't disclosed a quality shared by all such materials. In Holland Furniture, it invalidated a claim covering all starch glues that work as well as animal glue because the specification described the key ingredient only by what it does, not what it is — leaving gluemakers to experiment. Taken together, these cases stand for a single rule: when a patent claims an entire class of things, the specification must enable making and using the entire class.
- A specification is not required to walk through every possible version of the invention one by one. It can use a few examples, or describe a general quality shared by everything in the claimed class, as long as that disclosure lets a skilled person reliably make and use all of what is claimed — not just a subset. Likewise, a patent may require some reasonable experimentation to implement; not every variable needs to be spelled out. But there is a firm floor: the specification cannot simply send skilled scientists off to discover the invention for themselves.
- Amgen's claims covered every antibody that both binds to specific sites on PCSK9 and blocks PCSK9 from degrading LDL receptors — a potentially vast class. The record showed this class includes not just the 26 antibodies Amgen described by amino acid sequence but millions of others it had not. Amgen offered two methods for finding those undisclosed antibodies: the 'roadmap' (generate a wide range of candidates, screen each for binding and blocking) and 'conservative substitution' (start with a known working antibody, swap out amino acids, test whether the result still works).
- Both methods fail enablement because they are research programs, not teaching. The roadmap is Amgen's own trial-and-error discovery process described as a set of instructions. Conservative substitution requires scientists to make substitutions and then test the outcome — an uncertain prospect because the science of predicting how amino acid changes affect an antibody's three-dimensional structure and function is not yet fully understood. Both approaches leave scientists to 'painstaking experimentation,' which is not enabling a patent — it is, as the Court put it, giving scientists 'a hunting license.'
- Amgen's argument that the Federal Circuit applied a uniquely demanding standard to 'genus' patents was rejected. The Court agreed there is only one universal enablement standard, but said the Federal Circuit correctly applied it — because the principle is simply that the more one claims, the more one must enable. Amgen also warned that the ruling would chill breakthrough pharmaceutical research, but the Court said the balance between rewarding inventors and protecting the public is a policy call for Congress, not courts, to make.
Doctrinal impact
Cases affected by this decision
Reaffirms O'Reilly v. Morse (15 How. 62)
Reaffirmed that a patent claiming all means of achieving a result is invalid if the specification only teaches some of them.
Reaffirms The Incandescent Lamp Patent (159 U.S. 465)
Reaffirmed that a broad functional claim requires disclosure of a quality common to every item in the claimed class.
Reaffirms Holland Furniture Co. v. Perkins Glue Co. (277 U.S. 245)
Reaffirmed that defining an invention only by what it does, without saying what it is, leaves others to experiment and fails enablement.