Means-Plus-Function and Step-Plus-Function Claim Limitations (35 U.S.C. 112(f)): Memo to Examiners from the USPTO

On March 18, 2024, the United States Patent and Trademark Office (USPTO) sought to improve clarity of the patent prosecution record through providing patent examiners with reminders and increased guidance on analyzing means-plus-function and step-plus-functions claims.[1] Resources for Examining Means-Plus-Function and Step-Plus-Function Claim Limitations (35 U.S.C. 112(f)) (uspto.gov). In particular, the memo highlights guidance in the M.P.E.P relating to

• determining whether a claim limitation invokes § 112(f);
• ensuring that the record is clear with respect to § 112(f); and
• evaluating the description necessary to support a § 112(f) claim limitation under 35 U.S.C. 112(a) and (b).

Determining whether a claim limitation invokes 35 U.S.C. § 112(f)

M.P.E.P. § 2181 interprets 35 U.S.C. § 112(f), stating that “the broadest reasonable interpretation of a claim limitation that invokes 35 U.S.C. § 112(f) is the structure, material or act described in the specification as performing the entire claimed function and equivalents to the disclosed structure, material or act. As a result, § 112(f) limitations will, in some cases, be afforded a narrower interpretation than a limitation that is not crafted in ‘means plus function’ format.”

M.P.E.P. § 2181 further tells us explicit use of the term “means” or “step” recited in a claim that includes functional language triggers a presumption that § 112(f) applies. The presumption is overcome when the limitation further includes the structure, material, or acts necessary to perform the recited function.” M.P.E.P. § 2181 provides patent examiners with a three-prong analysis on whether to apply 35 U.S.C. §112(f):

1. the claim limitation uses “means” or “step” or a substitute for “means” that is generic placeholder term for performing the claimed function;
2. the term “means” or “step” or the generic placeholder is modified by functional language and linked by a transition word such as “for,” “configured to,” or “so that”; and
3. the term “means” or “step” or the generic placeholder is not modified by sufficient structure, material, or acts for performing the claimed function.

Ensuring that the record is clear with respect to § 112(f)

A patent examiner must expressly state in an office action if a claim is being interpreted as a means-plus-function claim, and if a claim limitation uses “means” or “step” but is not interpreted as a means-plus-function claim, the office action must include a statement as to why not. M.P.E.P. § 2181. A clear prosecution record informs the applicant, public, and courts on the examiner’s interpretations of the claims, search of prior art, and application of prior art.

Evaluating the description necessary to support a § 112(f) claim limitation under 35 U.S.C. 112(a) and (b)

The memo reminds patent examiners that after establishing that there is a §112(f) claim limitation, the supporting disclosure still must be evaluated under §§ 112(a) and (b) to ensure that the claim scope has clearly defined boundaries, the written description is adequate, and that the enablement requirement is met. Importantly, proper interpretation of § 112(f) limitations in writing during prosecution is crucial for the agency goal of creating a clear prosecution record. To have as clear a record as possible, the memorandum emphasizes that when claim terms are ambiguous, the examiner should include a statement on the record indicating what their interpretation is.

Training

The memo reminds examiners that refresher training is available, and points examiners to additional clarifying resources.

Takeaways

It is important to the USPTO, as well as for applicants, the public, and the courts, to have the clearest prosecution record possible. Regarding means-plus-function claims, it is important for applicants to look for a clear statement regarding why the claim limitation is being regarded under § 112(f) or not. If this interpretation is different from the intentions of the applicant, than the applicant should assert clarifying arguments as early as possible on the prosecution record. In the case of means-plus-function claim limitations, applicants should expect explicit, clear statements of the examiner’s interpretations in an office action and request such reasoning from the examiner if it is absent.

Endnotes

[1] 35 U.S.C. 112(f) provides:

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.