News & Events


Recent Court Decisions Drive Strategic Approaches to Pursuing Sound Patent Protection

By Procopio Partners Robert H. Sloss and Miku H. Mehta

The art of drafting patent applications and the task of litigating patents continue to evolve, driven by changes in review processes at the U.S. Patent and Trademark Office (USPTO) and rulings in the Federal Circuit. In particular, we have seen a dramatic change in both the risks and benefits associated with functional claim drafting. Of note to anyone dealing with patents are two recent Federal Circuit decisions that continue the trend of expanding the applicability of functional claiming. In particular, they highlight the importance both of taking a strategic prosecution approach that incorporates jurisprudence and business strategy and assessing closely claims asserted in litigation that might be subject to means plus function treatment.

Means plus function patent claims have been a staple for patent practitioners for many years. As provided in 35 U.S.C. § 112(f) (formerly 35 U.S.C. § 112, ¶ 6), an element of a patent claim “may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof.” The tradeoff for a means plus function recitation is that the claim scope is limited to the “corresponding structure, material, or acts described in the specification, and equivalents thereof.”

In the 2015 Williamson v. Citrix Online, LLC decision, the Federal Circuit held that a claim element may qualify for means plus function treatment even if it does not expressly use the term “means” or “steps.” According to the Court, the absence of “means” or “steps” creates a presumption that a claim is not means plus function, but the presumption can be rebutted by a showing that a particular limitation recites a function accompanied by a “nonce” word (or a word created once for a specific use) that equates to a means or step. The Williamson court concluded that the term “module” as it appeared in the claim limitation at issue was such a nonce word and that the limitation should be treated as means plus function. Subsequent cases have found words such as “mechanism,” “device,” and “element” to require means plus function treatment.

Two recent Federal Circuit decisions have continued this trend of expanding the applicability of section 112(f). First, in MTD Products Inc. v. Iancu (Aug. 12, 2019) the Court held that the Patent Trial and Appeal Board (PTAB) had improperly held that “mechanical control assembly” did not evidence a means plus function claim. The issue arose in a somewhat unusual context as it was the patent owner who contended that a claim in its patent should be subject to means plus function treatment; the patent owner took this position to avoid a prior art reference that did not have the structure disclosed in the subject patent. The Court held that the Board had properly found that “mechanical control assembly” is a nonce term that does not have an established meaning in the art (relating to steering mechanisms in lawn mowers) but operates as a generic label for a collection of parts. According to the Court, however, the Board erred in concluding that the description of a “ZTR control assembly” in the specification gave the claim limitation a sufficiently definite structure to take it outside section 112(f). Therefore, the Court vacated the Board’s finding that the affected claims were obvious.

In the second case, Grecia v. Samsung Electronics America, Inc. (Aug. 20, 2019) (nonprecedential), the patent owner appealed the district court’s dismissal of his claims on the basis of indefiniteness. The Court of Appeals affirmed the district court’s holding that the challenged claims were indefinite because under section 112(f) the term “customization module” was means plus function and the specification did not disclose a corresponding structure. Relying on Williamson, the Court held that “’module’ is a well-known nonce word that can operate as a substitute for ‘means.’” Because the only language the patent owner pointed to as providing structure that might render section 112(f) inapplicable was “customization module” and the specification did not explain how the use of “customization” to modify “module” created structure, the Court held that section 112(f) applied, and the claims were invalid.
These cases provide yet further examples of the Federal Circuit’s willingness to consider limitations that do not expressly refer to “means” or “steps” as means plus function limitations.

As a practical matter, prosecution attorneys should carefully consider the language and scope of their original specification and claims, as well as the amendments made during prosecution:

  • For example, it may be useful to draft specifications that are clear with respect to whether elements are structural or functional, and to the extent that functional elements are disclosed, provide appropriate language linking structure and function, to permit appropriate functional claiming.
  • Practitioners may want to consider having some claim sets directed to functional subject matter of an invention and some directed to structures.
  • For certain technologies, it is important to pay attention to how the courts are interpreting distinctions between functional and structural language, and to develop appropriate application drafting techniques.
  • Counsel should also pay careful attention to the products to be covered by the patent, should ensure that the specification is deep with examples and should use cases that provide as much functional and structural support as possible.

In litigation matters, attorneys representing an accused infringer should parse the language of asserted claims with particular diligence to ascertain whether specific limitations may be susceptible to treatment as means plus function claims subject to section 112(f). Similarly, counsel on behalf of a patent owner should identify claims that might fall within the Federal Circuit’s construct of a means plus function claim and assess the strength of the claim in that light.

As the Federal Circuit and USPTO continue to carefully scrutinize functional claim language under 35 USC 112(f), it is important to be aware of the changes in procedure and case law, and how they affect claim scope for various technologies. It is also crucial to develop and adjust strategies for drafting, prosecution and enforcement that take into account these changes.


Robert H. Sloss is a Partner in Procopio’s Silicon Valley office and a member of its Intellectual Property Litigation team. He advises clients on a matters pertaining to intellectual property counseling and litigation. Bob leverages his experience as a senior in-house lawyer at a major technology company to provide a unique set of skills to resolve clients’ legal disputes. He has broad experience in litigating patents related to a variety of technologies, including software, computer peripherals, mechanical devices and biotechnology, as well as matters involving copyright, trademark and trade secrets. Bob has appeared in courts throughout the U.S. and before the International Trade Commission and the Patent Trial and Appeals Board. He is admitted to practice in California State Courts, the U.S. Courts of Appeal for the Federal and Ninth Circuits, the U.S. District Courts for the Northern, Southern, Central and Eastern Districts of California, and the District of Colorado.

Miku H. Mehta is a Partner in Procopio’s Silicon Valley office, a member of its Intellectual Property team, and the leader of its Asia-Pacific Cross-Border practice group. He advises clients on intellectual property, patent prosecution and counseling, as well as trademarks and copyrights. Miku’s practice focuses on the preparation and prosecution of patent applications, due diligence projects, including preparation of opinions in the areas of patentability, validity, infringement and product clearance, and patent licensing. He has extensive experience in technology including computer software and hardware, networks, internet-related applications, environmental technologies, optics, mechanical engineering, business processes and medical devices, as well as registration and renewal of trademarks.