Amgen v. Sanofi: The Enablement Ruling

On May 18, 2023, the U.S. Supreme Court issued a unanimous decision in Amgen Inc. v. Sanofi, 598 U.S. 594 (2023), holding that Amgen’s patents on a genus of cholesterol-lowering antibodies were invalid for lack of enablement under 35 U.S.C. § 112(a). The ruling did not create a new legal test — it reaffirmed and sharpened a long-standing principle: the more a patent claims, the more its specification must enable. For university technology transfer offices (TTOs) and faculty inventors working in antibody therapeutics, gene editing, and other biologics where claims are often drafted around a functional result rather than a single defined molecule, the decision materially raises the bar for how broadly a genus claim can be written and still survive examination or litigation.

This guide explains what the Court actually held, how it differs from the patentable-subject-matter and non-obviousness doctrines covered elsewhere in this cluster, what the USPTO’s January 2024 examination guidelines changed (and didn’t change), and what it means in practice for drafting and prosecuting biotech patent claims that originate from university research.

Enablement is a Section 112 question, not a Section 101 or 103 question

It is easy to conflate Amgen v. Sanofi with the patent-eligibility line of cases (Alice/Mayo) or with non-obviousness disputes, because all three can sink a biotech patent. They are legally distinct doctrines that ask different questions:

35 U.S.C. § 101 (subject-matter eligibility) asks whether the claimed invention falls into a patent-eligible category at all — the Alice/Mayo framework CASRAI covers in 35 U.S.C. § 101: Patentable Subject Matter and the Alice/Mayo Eligibility Test.
35 U.S.C. § 103 (non-obviousness) asks whether the invention, as a whole, would have been obvious to a person of ordinary skill in the art — covered in 35 U.S.C. § 103: Non-Obviousness, the Graham Factors, and KSR.
35 U.S.C. § 112(a) (enablement) asks a different question entirely: assuming the invention is eligible and novel, does the patent’s written specification teach a person skilled in the art how to make and use the full scope of what is claimed, without undue experimentation? CASRAI’s general explainer on this statute is 35 U.S.C. § 112: The Specification, Enablement, and Written Description Requirements.

Amgen v. Sanofi is squarely a Section 112(a) enablement case. Amgen’s patents were never challenged on eligibility or obviousness grounds in the Supreme Court proceeding — the entire dispute was whether the specification enabled the breadth of what the claims covered.

The case: functionally defined antibody genus claims

Amgen holds patents covering PCSK9-inhibitor antibodies (marketed as Repatha), used to lower LDL cholesterol by blocking the PCSK9 protein from binding to LDL receptors. Rather than claiming a specific antibody sequence, the challenged claims covered the entire genus of antibodies that (1) bind to specific amino acid residues on PCSK9 and (2) block PCSK9 from binding to LDL receptors — a functional definition. The parties and lower courts agreed this functional description could, in principle, cover millions of possible antibodies.

Amgen’s specification disclosed the amino acid sequences of 26 antibodies it had actually made and shown to work, plus two general methods it argued a skilled scientist could use to find more: a “roadmap” (screen candidate antibodies against the process Amgen used to generate its own) and “conservative substitution” (make targeted amino-acid substitutions to a known working antibody and test whether function is retained). Sanofi argued — and the trial court and Federal Circuit agreed — that reaching the full breadth of the claimed genus from those 26 examples and two methods would require potentially undue trial-and-error experimentation, given how unpredictable antibody structure-function relationships are.

The holding: “the more you claim, the more you must enable”

Writing for a unanimous Court, Justice Gorsuch affirmed the Federal Circuit and held Amgen’s claims not enabled. The Court grounded its reasoning in the text of Section 112(a) itself, which requires the specification to enable any person skilled in the art “to make and use the same” — where “the same” refers to the full scope of the claimed invention, not merely a representative example of it. The opinion’s central line, since widely cited in patent prosecution and litigation: if a patent claims an entire genus of embodiments, “the more one claims, the more one must enable.”

Applying that principle, the Court reasoned that Amgen’s 26 working examples and two search methods amounted to little more than an invitation for skilled artisans to engage in “painstaking” trial-and-error discovery across a functionally-defined genus that could include millions of candidate antibodies — not a roadmap that reliably led to the full scope claimed. The Court was careful to note it was not announcing a new test or requiring inventors to enumerate every embodiment; enablement has never demanded a description of how to make and use every single species in a claimed genus. But where a genus is functionally defined and the field is unpredictable, a small number of worked examples plus a general research strategy can fail to meet the bar, particularly when the claimed genus is vast relative to what was actually disclosed.

What the ruling does not do

Several points of frequent confusion are worth stating directly, based on the opinion and the subsequent USPTO guidance:

It does not hold that functional genus claims are always unenforceable in biotech — narrower, well-supported genus claims with a workable, predictable structure-function relationship can still be enabled.
It does not change the legal standard for enablement; the Court explicitly framed its decision as an application of settled law (dating to 19th-century cases like O’Reilly v. Morse and The Incandescent Lamp Patent) to the facts of this case, not a new doctrine.
It does not affect written description, novelty, obviousness, or eligibility analysis independently — those remain separate statutory tests with their own case law.

USPTO’s January 2024 enablement guidelines

On January 10, 2024, the USPTO published Guidelines for Assessing Enablement in Utility Applications and Patents in View of the Supreme Court Decision in Amgen Inc. et al. v. Sanofi et al. in the Federal Register (89 FR 1563), directing examiners on how to apply Amgen during examination. The core message to examiners and applicants: the guidelines reaffirm that the existing In re Wands multi-factor framework — already used by examiners for decades to assess whether the amount of experimentation needed to practice the full claimed scope is “undue” — remains the operative test after Amgen. The eight Wands factors are:

The breadth of the claims
The nature of the invention
The state of the prior art
The level of ordinary skill in the art
The level of predictability in the art
The amount of direction provided by the inventor
The existence of working examples
The quantity of experimentation needed to make and use the invention, based on the disclosure

Rather than introducing a new checklist, the guidance instructs examiners to weigh Amgen‘s “the more you claim, the more you must enable” framing as part of the existing breadth-of-claims and quantity-of-experimentation factors — particularly for claims that functionally define a broad genus in an unpredictable field such as antibody therapeutics, other biologics, and certain chemical genus claims. In practice, this means examiners in antibody and biologics art units are expected to scrutinize whether working examples and disclosed methods are proportionate to the breadth of a functionally claimed genus, not simply whether some working examples and a general method exist.

Why this matters specifically for university tech transfer

Academic antibody, protein-engineering, and biologics discoveries are disproportionately exposed to this decision because of how early-stage university research typically gets disclosed and claimed:

Early invention disclosures often describe a small number of working antibodies or constructs, generated in a lab setting well before a company-scale discovery campaign has produced dozens or hundreds of variants. A claim strategy built around broad functional language (“any antibody that binds epitope X and achieves effect Y”) is now considerably more exposed to an enablement rejection or later invalidity challenge than it would have been before 2023.
Patent counsel drafting from a university invention disclosure should push for narrower, better-supported claim scope tied to what was actually reduced to practice — and for provisional and non-provisional filings to include, where possible, additional working examples, structural common features across the disclosed embodiments, and an explanation of why the claimed genus is more predictable than a purely functional definition might suggest. See CASRAI’s Invention Disclosure: What Researchers Submit to a TTO, and Why Timing Matters and Patentability Assessment: How a TTO Evaluates an Invention Disclosure for how disclosure quality feeds directly into claim drafting decisions.
Licensing value can be affected. A licensee’s diligence on a university-originated antibody or biologics patent family now routinely includes an enablement risk assessment, not just a freedom-to-operate and novelty review. TTOs negotiating exclusive licenses on genus-claimed biologics patents should expect this to surface in representations, warranties, and valuation discussions — see The Technology Transfer Process: From Invention Disclosure to Licensing and Revenue Distribution.
Continuation practice becomes more important. Filing continuation applications that narrow claims to the specific, well-supported embodiments actually disclosed — while the broader genus claim is pursued or defended separately — gives an institution a fallback position if the broadest claims face an enablement challenge post-grant.
The decision reaches beyond antibodies. While Amgen is an antibody case, its reasoning applies to any functionally-defined genus claim in an unpredictable art — small-molecule chemical genus claims, CRISPR/gene-editing constructs, and other biologics all face the same “more you claim, more you must enable” scrutiny.

Practical checklist for TTOs and inventors after Amgen v. Sanofi

Ask whether a claim is functionally defined (defined by what it does) rather than structurally defined (defined by what it is) — functional genus claims carry the highest enablement risk post-Amgen.
Document every working embodiment actually made and tested at the time of disclosure, not just the first one that worked — more working examples strengthen the enablement record.
Ask patent counsel to assess claim breadth against the Wands factors specifically, not just novelty and obviousness, before filing.
Consider a tiered claim strategy: broad genus claims alongside narrower, well-enabled dependent claims and continuation applications as a fallback.
For existing issued patents in an antibody or biologics portfolio with broad functional genus claims, flag them for a fresh enablement risk review before relying on them in licensing negotiations or litigation.

Frequently asked questions

Is Amgen v. Sanofi a patent-eligibility case?

No. It is an enablement case under 35 U.S.C. § 112(a). Patent-eligibility (35 U.S.C. § 101, the Alice/Mayo framework) and non-obviousness (35 U.S.C. § 103) are separate legal tests not addressed in this decision. See 35 U.S.C. § 101 and 35 U.S.C. § 103 for those doctrines.

Did the Supreme Court create a new legal test for enablement?

No. The Court described its decision as applying settled enablement law — including principles traced back to 19th-century Supreme Court precedent — to Amgen’s specific claims. The USPTO’s January 2024 guidance confirms that the pre-existing In re Wands multi-factor framework remains the operative examination standard.

Does this mean genus claims on antibodies are no longer patentable?

No. Narrower genus claims, better supported by a larger or more representative set of working examples and a predictable structure-function relationship, can still satisfy enablement. The decision raises the bar specifically for very broad, functionally-defined genus claims relative to what the specification actually discloses.

What did the USPTO’s January 2024 guidelines change?

The guidelines, published in the Federal Register on January 10, 2024 (89 FR 1563), direct examiners to apply Amgen‘s “the more you claim, the more you must enable” principle within the existing Wands factors framework, rather than introducing a new test. For antibody and other biologics claims, examiners are expected to scrutinize whether disclosed working examples and methods are proportionate to the breadth of a functionally-claimed genus.

Does Amgen v. Sanofi only affect antibody patents?

The case itself involved antibody claims, but its reasoning applies to any functionally-defined genus claim in an unpredictable field, including other biologics, gene-editing constructs, and certain chemical genus claims.

Primary sources

U.S. Supreme Court, Amgen Inc. v. Sanofi, 598 U.S. 594 (2023), decided May 18, 2023 (opinion available via supremecourt.gov).
USPTO, Guidelines for Assessing Enablement in Utility Applications and Patents in View of the Supreme Court Decision in Amgen Inc. et al. v. Sanofi et al., 89 FR 1563 (Jan. 10, 2024), published in the Federal Register.
35 U.S.C. § 112(a) (statutory text of the enablement and written description requirements).