When a claim term is construed as a means plus function limitation, the recited “means” is limited to only the specific structures disclosed in the specification for performing the recited function, and a limited range of equivalents.
The Federal Circuit recently issued two decisions1 in which it made clear that while Williamson2 removed the “strong,” or “heavy” presumption that §112(f) does not apply when a “means” term is not present, a rebuttable presumption still remains. The party challenging the presumption must present evidence that shows by a preponderance of the evidence that one of ordinary skill in the art would find the term does not recite “sufficiently definite” structure.3 The two decisions should give courts pause before applying §112(f) to claims that do not use the term “means.”
A means plus function claim limitation describes a claim element in terms of the function it performs rather than the specific structure of the element. But when a claim term is construed as a means plus function limitation, the recited “means” is limited to only the specific structures disclosed in the specification for performing the recited function, and a limited range of equivalents.4 Falling under this provision can have drastic consequences by significantly limiting the scope of the claim, or worse, if the specification does not disclose both adequate “structure” and a clear linkage between the structure and the means term, the entire claim could be invalid as indefinite.5 This can be particularly challenging for patents that claim computer-implemented functions. If §112(f) applies, the specification generally must disclose an algorithm for each recited function.6 Williamson has, therefore, added another powerful arrow to a patent challenger’s quiver for invalidating patent claims with functional language.
Dyfan, LLC v. Target Corp.
In Dyfan, the claim did not include “means” and instead used the word “code” configured to perform a series of recited functions. The patent holder presented unrebutted expert testimony that the term “code” connotes structure and that the claimed functions could be implemented with “off-the-shelf” code or applications.7 The Court reversed the District Court’s decision to apply §112(f), finding that the District Court’s characterization of the claim as “purely functional” was unsupported and that the District Court did not give proper weight to the presumption or the unrebutted expert testimony. The Court also reiterated that unlike the mechanical arts, the “structure” in software claims are in part defined by the recited functions such that it would be incorrect to only look to the “code” portion of the claim for the structure while ignoring the remaining functional elements.8
VDPP LLC v. Vizio, Inc.
VDPP had a similar outcome. In that case the disputed claim terms were “storage” and “processor” each adapted to perform one or more functions. The Court reversed the District Court’s decision to apply §112(f) because the challenger did not present any evidence to rebut the presumption that §112(f) did not apply and the District Court did not give any effect to the presumption and concluded without evidence that §112(f) should apply.9
The Dyfan and VDPP decisions along with the legal precent cited in those decisions will be useful for patent owners seeking to avoid application of §112(f). For parties (usually patent challengers) seeking to overcome the presumption, these decisions make clear that evidence is necessary and that the evidence must demonstrate that a person of ordinary skill in the art would believe the claim terms do not recite sufficiently definite structure. For patent practitioners that prepare patent applications, in this author’s opinion, best practice remains to conservatively assume §112(f) will be applied and ensure that the specification includes a sufficiently detailed algorithm for all claimed computer implemented functions. It would also be good practice for practitioners to use terms that have been held by the courts to connote sufficient structure, such as the “storage” and “processor” terms in VDPP and avoid coined terms that do not have a recognized meaning, such as the “user identification module” in Rain Computing.10
1 Dyfan, LLC v. Target Corp., 28 F.4th 1360 (Fed. Cir. 2022) and VDPP LLC v. Vizio, Inc., No. 2021-2040, 2022 WL 885771 (Fed. Cir. Mar. 25, 2022)
2 Williamson v. Citrix Online, LLC, 792 F.3d 1339 (Fed. Cir. 2015)
3 Dyfan, 28 F.4th at 1366
4 See 35 USC §112(f)
5 See, e.g., Rain Computing, Inc. v. Samsung Elecs. Am., Inc., 989 F.3d 1002, 1007 (Fed. Cir. 2021).
7 Dyfan, 28 F.4th at 1368.
9 VDPP, No. 2021-2040, 2022 WL 885771, at *3.
10 Rain Computing, Inc., 989 F.3d 1002.