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Means-Plus-Function Patent Claims: Treatment in Prosecution, Litigation, and Post-Grant Proceedings

Recording of a 90-minute premium CLE video webinar with Q&A

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Conducted on Thursday, June 24, 2021

Recorded event now available

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This CLE course will provide patent counsel with an in-depth look at means-plus-function and/or functional claims, and the benefits and risks of using means-plus-function and/or functional claims given district court litigation, actual patent claims issued by the USPTO, and PTAB post-grant proceedings. The panel will offer their experiences and best practices to overcome the challenges of means-plus-function claims and leverage 112(f) and functional claims for maximum patent protection.


Section 112(f) reads: "An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof."

Section 112(f) provides a statutory tool allowing the patent drafter to write claims reciting a function and refer to the specification for details of the structures, materials, and acts associated with that claimed function. While having a claim construed as a means-plus-function claim may mean a narrower construction (since the patent owner is limited to the structure disclosed in the specification "and equivalents thereof"), the claim format may be useful when the subject matter claimed is best described functionally.

Nearly every technological field uses means-plus-function claiming. Practitioners in all technologies should consider means-plus-function claims with their built-in literal equivalents as a claiming alternative.

As Ms. Hooson, Dr. Gao, and Mr. Irving will emphasize, the perceived “narrowness” of means-plus-function claims can be advantages in the life sciences and particularly for pharmaceutical claims. Mr. Gutowski will be providing his analysis of means-plus-function claims in the mechanical, computer, and electrical fields.

As will be revealed, counsel should weigh the pros and cons of such claims as they are limited to the subject matter described in the specification as being linked to the materials, structures, and uses for accomplishing the function recited in the claims and statutory, i.e., literal, equivalents thereof. Omitting the term "means" apparently no longer provides a "strong" presumption that 112(f) is not applicable, according to the en banc portion of Williamson v. Citrix Online L.L.C. (Fed. Cir. 2015). And the MPEP expressly condones the use of nonce words (those coined for special use), such as "components for," as a placeholder for the "means for."

There is also a danger that failure to identify the structure, materials, or acts corresponding to the claimed function under a 112(f) scenario may result in an invalidated indefinite claim under 112(b).

Listen as our authoritative panel examines how both means-plus-function and functional claims are used in different fields, as mentioned above, and their future potential.



  1.  Overview of the use of means-plus-function claims
    1. Courts
    2. PTAB
    3. Means-plus-function claims in the electrical, computer, and mechanical fields, as well as in the life sciences, including potential as a strategy in light of the current stance in the U.S. on antibody genus claims as seen in Amgen v. Sanofi (Fed. Cir. 2021)
  2. Benefits of using means-plus-function claims
    1. Link to specification to avoid prior art and to avoid problems under 35 USC 112
    2. Provide an expansive claim scope when the specification may disclose only specific
    3. Include statutory equivalents to what is linked in the specification, but such statutory equivalents are considered in the context of literal infringement, not the doctrine of equivalents
    4. Provide added difficulty for third parties challenging patentability at the PTAB or validity in a district court
    5. Provide challenges to third-party design-around because of the specter of statutory equivalents
  3. Challenges/limits with applying means-plus-function claims
    1. Narrowness and linking in the specification
    2. Determining the scope of statutory equivalents
    3. USPTO treatment
  4. Functional claims
    1. When does 112(f) apply even though no "means" language is present?
    2. The use of nonce words
  5. Best practices for preparing, defending, and enforcing means-plus-function claims


The panel will review these and other noteworthy issues:

  • What are the possibilities for means-plus-function claims in life science patents?
  • What are the benefits and limitations of using means-plus-function patent claims in many technical fields?


Gao, Michelle
Xiaoguang Michelle Gao, Ph.D., J.D.

Assistant General Patent Counsel
Eli Lilly and Company

Dr. Gao provides IP support for Lilly BioMedicines assets and the Lilly Biotechnology Center in San Diego.  She...  |  Read More

Hooson, Sarah
Sarah Hooson

Director, Legal
Merck Sharp & Dohme

Ms. Hooson is director in the Intellectual Property Group at Merck in Rahway, NJ. Her present responsibilities include...  |  Read More

Gutowski, Anthony
Anthony M. Gutowski

Finnegan Henderson Farabow Garrett & Dunner

Mr. Gutowski focuses on client counseling, patent procurement, and patent enforcement. He advises clients on patent...  |  Read More

Irving, Thomas
Thomas L. Irving

Finnegan Henderson Farabow Garrett & Dunner

Mr. Irving has 35 years of experience in the field of IP law. His practice includes due diligence, patent prosecution,...  |  Read More

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