Introduction : The US Supreme Court’s decision in Amgen Inc. v. Sanofi has fundamentally changed the risk calculus for broad genus claims, especially in biotechnology and pharmaceuticals. The Court confirmed that a patentee may claim an entire genus only where the specification enables a skilled artisan to make and use the full scope of the claimed invention without undue experimentation. For innovators seeking broad protection, the lesson is not that genus claims are dead; it is that they must be supported by disclosure proportional to their scope.
What Amgen Decided
In Amgen, the Supreme Court unanimously held that Amgen’s antibody genus claims were invalid for lack of enablement. Although Amgen had identified and patented specific antibodies, its claims covered an entire class of antibodies defined principally by function. The Court held that the specification did not enable a person skilled in the art to make and use every antibody within the genus without undue experimentation.
The Court’s guiding principle was straightforward: “the more a party claims, the more it must enable.” A patentee cannot use functional language to claim a broad class of inventions while disclosing only a narrow path to reach some members of that class.
Importantly, Amgen did not abolish genus claims. The Court expressly recognised that enablement may require some experimentation, but only a reasonable amount. The issue is whether the disclosure, considered as a whole, permits a skilled artisan to make and use the full scope of the claim without undue trial and error.
The Enablement Standard After Amgen
Enablement requires the patent specification to teach a person of ordinary skill in the art how to make and use the claimed invention. In the genus-claim context, that means the disclosure must enable the claimed genus, not merely the examples specifically described.
The Supreme Court rejected the argument that enablement should be measured by the cumulative time and effort needed to make every embodiment within a claim. However, it also made clear that a patentee cannot avoid the enablement requirement by defining a genus functionally and leaving the skilled artisan to discover which members work.
The USPTO’s January 2024 enablement guidance reaffirmed that the controlling test remains whether the specification enables the full scope of the claims without undue experimentation. The guidance applies across technologies and directs examiners to consider the familiar In re Wands factors.
The Wands Factors Remain Central
The Wands factors provide the practical framework for assessing enablement. They include:
- 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.govinfo+1
After Amgen, the first and last factors carry particular weight. Broad claims require broad and reliable disclosure. If reaching untested members of the genus requires substantial screening, optimisation, or iterative experimentation, the claim is vulnerable.
Why Functional Genus Claims Are High Risk
Functional claiming is often attractive because it captures future developments and avoids limiting the claim to a particular structure. In antibody patents, for example, claims may define the genus by binding to a target or achieving a therapeutic result rather than by amino-acid sequence.
But Amgen demonstrates the danger. Functionally defined genus claims may encompass millions of possible candidates, and if the patentee has disclosed only a route to a subset, the claim may require the public to engage in extensive discovery to identify the remaining embodiments. The Federal Circuit’s earlier analysis in the Amgen litigation emphasised that the claims covered millions of candidates and required generation and screening of each candidate to determine whether it met the claimed functional limitations.
The result is a heightened disclosure burden for patents claiming broad families of antibodies, small molecules, polymers, materials, software models, or other inventions where structure and function are not tightly correlated.
Drafting Principle: Match Claim Scope to Disclosure
The central drafting rule after Amgen is proportionality. The breadth of the claim should be matched by the breadth, quality, and predictability of the technical disclosure.
A strong genus claim should be supported by:
- A clearly identified unifying structural or technical feature shared across the genus.
- Sufficient representative embodiments across the claimed range.
- Working examples demonstrating that the genus is not merely aspirational.
- Guidance enabling the skilled artisan to identify or make additional members without undue experimentation.
- Data or reasoning showing predictability across the claimed scope.
- Clear definitions of functional limitations, avoiding ambiguity where possible.
A patentee should not assume that a few examples will support an expansive claim. Where the art is unpredictable, the specification must provide more teaching, more examples, and more structural guidance.
Identify a Common Quality – But Prove It
The Supreme Court observed that a specification may support a broad claim by identifying a quality that is common to the functional embodiments. However, identifying a common quality is not sufficient by itself; the disclosure must also enable the skilled artisan to make and use the genus in light of that common feature.
For example, in an antibody case, a common binding epitope, conserved structural motif, or shared mechanism of action may help support a genus. But the specification should explain how that feature enables the skilled artisan to generate additional antibodies within the claimed class and predict that they will possess the claimed function.
This principle applies beyond life sciences. In materials science, battery chemistry, catalysts, polymers, and AI-related inventions, a broad claim should identify the technical principle that makes the genus work – not merely list preferred examples.
Use Ranges and Sub-Genera Carefully
Broad numerical ranges can be useful, but they can also create enablement exposure. If a claim covers a wide range of temperatures, concentrations, sequence identities, model parameters, or material compositions, the specification should show that the invention can be practised across the range.
Where the disclosure supports only part of the range, consider claiming narrower sub-genera or species claims. A layered claim set can preserve fallback positions while reducing the risk that a single broad claim invalidates the entire patent family.
A well-structured claim hierarchy may include:
- A broad genus claim supported by the strongest common technical feature.
- Intermediate sub-genus claims tied to specific structures, ranges, or mechanisms.
- Species claims covering validated embodiments.
- Method claims directed to concrete uses, processes, or technical improvements.
This approach provides commercial breadth without placing excessive enablement weight on a single claim.
Working Examples Are Not a Safe Harbour
Working examples strengthen a patent, but they do not automatically enable every embodiment within a broad claim. The relevant question is whether the examples, combined with the specification’s teaching, give the skilled artisan a reasonable route across the claimed genus.
Patentees should therefore avoid relying solely on isolated examples. The specification should explain why the examples are representative, identify the variables that matter, and provide enough direction for the skilled artisan to extend the invention beyond the examples.
This is particularly important in unpredictable fields. In such fields, a patentee may need to disclose multiple species across the genus, comparative data, structure-function relationships, and practical guidance for selecting or making additional embodiments.
PTAB and Litigation Implications
Post-Amgen, challengers frequently pair Section – 112 enablement attacks with Section – 103 obviousness challenges. A challenger may argue that the patent claims a broad genus but enables only a small subset, leaving the remainder to routine experimentation or later invention.
The USPTO’s 2024 guidance noted that, in post-Amgen Federal Circuit cases and PTAB decisions citing Amgen, the genus claims at issue were found not enabled across multiple technologies. While that trend does not make every genus claim invalid, it signals that tribunals are scrutinising the relationship between claim breadth and disclosure with heightened care.
For patent owners, this means enablement should be addressed not only during prosecution but also in litigation strategy. Expert declarations should explain why the disclosure permits the full scope of the claims to be practised, using concrete technical evidence rather than conclusory assertions.
Practical Drafting Checklist
Before filing or asserting a genus claim, patentees should ask:
- Does the claim cover only inventions that share a genuine, enabling technical feature?
- Does the specification enable the full scope of the claim, including embodiments beyond the examples?
- Have we disclosed representative embodiments across the relevant structural or functional space?
- Have we explained how a skilled artisan can make or identify additional members?
- Have we supported broad ranges with data, reasoning, or predictability evidence?
- Have we included fallback species and sub-genus claims?
- Have we avoided purely functional language where structural features could more reliably define the invention?
- Have we preserved evidence of unexpected results and the predictability of the art?
Key Takeaway
The post-Amgen era rewards careful, technically grounded claiming. Broad genus claims remain available, but they must rest on a disclosure that genuinely teaches the full scope of the invention. The most durable patents will claim breadth supported by structure, mechanism, predictability, and practical enablement – not breadth supported by functional aspiration alone.
The issues discussed in this article form part of the broader landscape of pharmaceutical Intellectual Property law, which will be explored at Pharma Symposium 2026, scheduled for 7-8 December at Park Hyatt Hyderabad and 9-10 December at Hilton Mumbai. Organized by Khurana & Khurana, IIPRD and international IP law firm partners, the symposium will bring together perspectives on pharmaceutical patent litigation, patent protection strategies, regulatory exclusivity and developments across the United States, Europe, China and India. For details of the programme and participating speakers, please refer: https://www.iiprd.com/upcoming-events/
Author : Vipasha Srivastava, In case of any queries please contact/write back to us via email to [email protected] or at IIPRD
Endnotes
- Amgen Inc. v. Sanofi, 598 U.S. 597 (2023), holding that Amgen’s antibody genus claims were not enabled.
- Congressional Research Service, Amgen v. Sanofi: Supreme Court Holds Patents Claiming Antibody Genuses Invalid for Lack of Enablement (2023).
- USPTO, “Guidance for Determining Compliance with 35 U.S.C. 112(a) in View of the Supreme Court Decision in Amgen Inc. v. Sanofi,” 89 Fed. Reg. 1018 (Jan. 10, 2024).
- In re Wands, 858 F.2d 731 (Fed. Cir. 1988), identifying the enablement factors later summarised in USPTO guidance.govinfo+1.
- Taft Stettinius & Hollister LLP, “Post-Amgen Patent Playbook: Section 112 Under the Microscope” (2026).
- Troutman Pepper, Amgen Inc. et al. v. Sanofi client memorandum, noting that broad functional genus claims require disclosure enabling the full claimed scope without more than reasonable experimentation.
- Wilson Sonsini, The PTAB Review (May 2023), discussing the Supreme Court’s statement that enablement is not measured by the cumulative effort to make every embodiment.
- Sterne Kessler Goldstein & Fox, “Case Studies and Trends at the PTAB Involving 35 U.S.C. Section 112,” discussing the Federal Circuit’s analysis of the millions of antibody candidates encompassed by the Amgen claims.
- National Law Review, “Watch Post-Amgen Enablement Case Law in the United States Patent and Trademark Office” (2024), noting that genus claims in post-Amgen Federal Circuit and PTAB decisions were found not enabled.