On March 18, 2024, the USPTO issued a memorandum to its Examiners reminding them of the resources and proper analysis for interpreting limitations under 35 U.S.C. § 112(f), which are commonly referred to as “means-plus-function” or “step-plus-function” limitations. These types of claim formats provide an option to claim an element as a means or step for performing a specified function without reciting any structure, material, or acts.
Although § 112(f) limitations have traditionally been less common in life sciences technologies as compared to, for example, electronics and devices, they are sometimes used as a drafting strategy to capture claim scope of interest.
The USPTO memorandum does not include any substantive change for how Examiners are to conduct examination of claims involving such limitations, but rather “reinforces the importance” of properly interpreting these limitations.
35 U.S.C. § 112(f) provides the following:
ELEMENT IN CLAIM FOR A COMBINATION.—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.
According to the memorandum, a limitation that is found to invoke § 112(f) “must be limited to the structure, material, or acts described in the specification as performing the entire claimed function and equivalents to the disclosed structure, materials, or acts.”
Since a § 112(f) limitation must be limited to what is described in the specification, the memorandum notes that “an important consideration when searching for and applying prior art” is that, in some cases, § 112(f) limitations will be afforded “a narrower interpretation than a limitation that is not crafted in means-plus-function or step-plus-function format.”
The memorandum reiterates the three-prong analysis for determining whether a claim limitation invokes § 112(f). Specifically, an Examiner should invoke § 112(f) if:
(A) the claim limitation uses the term “means” or “step” or a term used as a substitute for “means” that is a generic placeholder (also called a nonce term or a non-structural term having no specific structural meaning) for performing the claimed function;
(B) the term “means” or “step” or the generic placeholder is modified by functional language, typically, but not always linked by the transition word “for” (e.g., “means for”) or another linking word or phrase, such as “configured to” or “so that”; and
(C) the term “means” or “step” or the generic placeholder is not modified by sufficient structure, material, or acts for performing the claimed function.
The memorandum explains that there is a presumption that § 112(f) is invoked when the claim limitation “explicitly uses the term ‘means’ or ‘step’” and includes functional language, but that this presumption can be overcome if “the claim further includes the structure, material, or acts for performing the function,” thereby resulting in § 112(f) not being invoked.
The memorandum also explains that there is a presumption that § 112(f) is not invoked when the claim limitation “does not use the term ‘means’ or ‘step,’” but that this presumption can be overcome if “the limitation recites functional language along with a generic placeholder term instead of ‘means’ and fails to recite sufficiently definite structure for performing the function,” thereby resulting in § 112(f) being invoked. The memorandum emphasizes that there is flexibility in the generic placeholder terms that can be used instead of “means” and that there are “no absolutes or approved lists” of such terms.
The memorandum reiterates the “critical” importance of the Examiner establishing its interpretation of § 112(f) limitations in the record.
Finally, once an Examiner has determined that § 112(f) is invoked, “the adequacy of the supporting disclosure must be evaluated under § 112(a) and (b) to determine whether the boundaries of the claim scope are clearly defined, an adequate written description has been provided, and the claim is fully enabled.” The memorandum explains that if 112(f) is intended to be relied on, the specification should disclose a corresponding structure; not doing so could result in a “lack adequate written description and may not be sufficiently enabled to support the full scope of the claim under § 112(a).”
Likewise, for computer-implemented § 112(f) limitations, “the specification must disclose an algorithm for performing the claimed specific computer function, or the claim should be found indefinite.” Such algorithms can be expressed “in any understandable terms including as a mathematical formula, in prose, in a flow chart, or in any other manner that provides sufficient structure.”
Although means-plus-function limitations can be a helpful tool for describing an invention, potential issues may arise if such a limitation is not found to be adequately described in the specification or is described in a way that results in an undesirably narrow interpretation of the limitation. Applicants should be aware of these possibilities and consider them when drafting a limitation in a means-plus-function or step-plus-function format. Alternatively, drafting the limitation to avoid invoking § 112(f) may be desirable in some situations, including if there is a concern that the Examiner may narrow interpretation of the limitation to an undesirable scope. For instance, although a narrow interpretation of the limitation may be beneficial for establishing novelty and non-obviousness, it may make it easier for a competitor to design around the limitation based on its narrow interpretation.
The issue of § 112(f) limitations in the context of antibodies is currently at issue in In re Xencor. The claims at issue in In re Xencor were found to invoke § 112(f) based on claim language reciting “means” with respect to a function performed by the antibody (“for binding human C5 protein”). The case has been recently remanded back to the USPTO after appeal at the Court of Appeals for the Federal Circuit so that the USPTO can convene their Appeals Review Panel to “clarify the USPTO’s position on the proper analysis of Jepson-format and means-plus-function claims in the field of biotechnology, and particularly in the antibody art” and to issue “a revised decision.” See In re Xencor, 23-2048 (Fed. Cir. January 23, 2024) (remand order). In view of the newly issued memorandum, it will be interesting to see how the USPTO implements “means‑plus-function” in the life sciences, and particularly in the antibody technology area.
[View source.]
