TAKEAWAY: The Federal Circuit’s holding in Williamson v. Citrix Online LLC increases the likelihood that a claim phrase will be interpreted as a means-plus-function recitation in the absence of the word “means” in the phrase. Practitioners may take a variety of measures to try and avoid such inadvertent application of §112(f), such as avoiding “nonce” words in the claims, providing a full list of corresponding structure and alternatives in the specification for potential functional claim elements, and by taking a variety of claim approaches to avoid all of the claims being subject to a means-plus-function construction. 

The Federal Circuit’s holding in Williamson v. Citrix Online in June of 2015 is a decided movement away from the strong presumption against applying a means-plus-function claim interpretation in the absence of the word “means.” As a result of the Williamson holding, and despite the decreasing popularity of means-plus-function claiming, claim terms without “means for” language may nevertheless be subject to a means-plus-function interpretation under 35 U.S.C. §112(f) (previously §112, sixth paragraph).

In the Williamson opinion, the Federal Circuit held that the standard for determining whether a means-plus-function analysis applies is:

whether the words of the claim are understood by persons of ordinary skill in the art to have a sufficiently definite meaning as the name for structure. . . . When a claim term lacks the word “means,” the presumption [against applying a means-plus-function analysis] can be overcome and §112, para. 6 [now §112(f)] will apply if the challenger demonstrates that the claim term fails to “recite sufficiently definite structure” or else recites “function without reciting sufficient structure for performing that function.”

Id. Several strategies may be considered in strengthening an application against inadvertent interpretation under a means-plus-function analysis in the wake of Williamson. For example, practitioners may review claims to avoid potential generic “nonce” words, combined with functional language, that could trigger a means-plus-function analysis. The Williamson opinion and the MPEP both provide several examples of nonce words beyond “means,” such as “module” (at issue in Williamson), “mechanism,” “element,” “device,” “unit,” “component,” “member,” “apparatus,” “machine,” and “system.”

In drafting new specifications post-Williamson, practitioners may include more specific or extensive descriptions of structure corresponding to potential functional claim elements and alternatives, so as to maintain adequate claim scope and avoid indefiniteness issues if inadvertent §112(f) claiming is found. Finally, practitioners may consider diversifying the wording of their claims to help avoid interpretation of all of the claims under §112(f). For example, a practitioner may consider relying on one or more method claims to cover important functions to reduce the risk of an undesired slip into a means-plus-function analysis under the Williamson standard.