Means-Plus-Function Patent Claims After Williamson: Navigating the New Standard

Assessing Impact on Prosecution, Litigation and IPRs

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

Conducted on Thursday, December 8, 2016

Recorded event now available

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Program Materials

This CLE webinar will provide patent counsel with a review of how means-plus-function and/or functional claims are used after the Williamson decision as well as the benefits and risks involved with using means-plus-function and/or functional claims in view of both litigation in the district courts and IPRs before the PTAB. The panel will offer their experiences and best practices for overcoming the challenges of means-plus-function claims and leveraging Section 112(f) and functional claims for maximum patent protection.


In Williamson v. Citrix Online L.L.C. the Federal Circuit issued a decision, including an en banc portion, relating to means-plus-function claims. This decision is having a dramatic impact on interpreting functional claim terms, regardless of whether claim language is being construed in prosecution, post-grant challenges at the PTAB, or district court litigation. Notably, a doyen of U.S. patent law, Judge Newman, wrote a lengthy and spirited dissent against the en banc portion of Williamson.

According to the en banc part of Williamson, the previously “strong” presumption of not applying a means-plus-function analysis unless a claim recites the word “means,” is not so strong anymore. Rather, even if no “means” term is used, §112(f) (pre-AIA §112(6)) may apply if the claim fails to “‘recite sufficiently definite structure’ or else recites ‘function without reciting sufficient structure for performing that function.’” Use of the term “means” will continue to invoke a rebuttable presumption that §112(f) applies.

Means-plus-function claiming is utilized in nearly every technological field, including mechanical, electrical, computer, food and other chemical formulation technologies, life sciences, and pretty much every other technology under the sun. However, 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 function recited in the claims and statutory equivalents thereof. And now, simply omitting the term “means” apparently no longer provides the protection that a “strong” presumption that §112(f) does not apply.

Listen as our authoritative panel utilizes the Williamson decision, particularly its en banc portion, as a spring-board for examining how both means-plus-function and “functional” claims are used in different fields. The panel will examine the benefits and risks involved with using means-plus-function and/or functional claims in view of both litigation in the district courts and IPRs before the PTAB. The panel will also offer best practices for leveraging §112(f) and functional claims for maximum patent protection.



  1. Review of Williamson, the new standard and Judge Newman’s dissent
  2. Overview of the use of means-plus-function (mpf) claims
    1. Mechanical
    2. Electrical, including computer
    3. Food and chemical formulation technology
    4. Pharma
  3. Benefits of using mpf claims
    1. Link to specification to avoid prior art
    2. Provide an expansive claim scope when the specification is carefully drafted to encompass all embodiments intended to be covered by the language
    3. Include statutory equivalents to what is linked in the specification, but such statutory equivalents are considered in the context of literal infringement, not doctrine of equivalents
    4. Added difficulty for third parties challenging validity at the PTAB or in district court
    5. Potential uncertainty of statutory equivalents creates challenges to third-party design-arounds
  4. Challenges/limits with applying mpf claims
    1. Narrowness and linking in the specification
    2. Defining statutory equivalents
    3. USPTO treatment
  5. Functional claims
    1. When does §112(f) apply even though no “means” language is present?
  6. Best practices for addressing those changes
    1. Real life examples
    2. Linking


The panel will review these and other key issues:

  • What impact will the Williamson decision have on functional claim interpretation?
  • What are the benefits and limitation of using means-plus-function patent claims?
  • What practices can counsel employ to leverage §112(f) to increase the likelihood of surviving IPRs?


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

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

C. Brandon Rash
C. Brandon Rash

Finnegan Henderson Farabow Garrett & Dunner

Mr. Rash practices all aspects of patent-related work, including litigation, post-grant proceedings, appeals, and...  |  Read More

Wanli Tang, Ph.D.
Wanli Tang, Ph.D.

Jones Day

Dr. Tang has extensive experience working with branded pharmaceutical companies, especially in litigation involving...  |  Read More

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