In Rain Computing, Inc. v. Samsung Elecs. Co., No. 2020-1646 (Fed. Cir. Mar. 2, 2021), the Federal Circuit reversed a judgment of non-invalidity and in doing so provided clarity to its post-Williamson (792 F.3d 1339 (Fed. Cir. 2015)) means-plus-function case law and the required disclosure of structure to avoid an indefiniteness issue. This guidance is especially useful to patent owners and, in particular, those in the computer fields, as the decision addresses the claim term “module” in a § 112 ¶ 6 (now § 112(f)) analysis, and the accompanying disclosure of structure required when the function is performed by a general-purpose computer.

The claims at issue in Rain concerned “delivering software application packages to a client terminal in a network based on user demands configured to control access.” The district court determined one of the terms, “user identification module,” to be a means-plus-function term subject to § 112 ¶ 6 treatment but not indefinite. Based on the parties’ joint stipulation, the district court entered judgment that the asserted claims were neither infringed nor invalid for indefiniteness. On appeal, the Federal Circuit reversed the judgment as to invalidity for indefiniteness and dismissed the infringement issue as moot. In doing so, the court offered clarity on several key issues.

First, the court noted the term “module” is a well-known nonce word that can operate as a substitute for “means,” and here, like in Williamson, it did not provide any indication of structure. Slip op. at 5. Further, the prefix “user identification” did not impart structure, as it merely described the function of the module: to identify a user. Id. Accordingly, the claim language failed to provide any structure for performing the claimed functions, rendering the claims subject to § 112 ¶ 6. Id.

Second, the court rejected the argument that amending the claim from “a user identification module for accessing . . .” to “a user identification module configured to control access of . . .” removed the means-plus-function language. Id. at 6. The purely functional claim language reciting what the “user identification module” was configured to do provided no structure. Id.

Third, the court rejected the implication that a means-plus-function term cannot be nested in a method claim. Id. Rain had cited an appellate brief, filed by Patent Office examiners, in support of its position that the claim should not be subject to § 112 ¶ 6 treatment. Id. In relevant part, the brief stated the claims at issue were directed to a method rather than an apparatus, and therefore the limitation “user identification module . . .” did not invoke § 112 ¶ 6. Id. The court reiterated that applicants are free to invoke § 112 ¶ 6 for a claim term nested in a method claim, and that it has never held otherwise. Id.

Finally, the court addressed indefiniteness, which requires patentees to disclose adequate corresponding structure linked to means-plus-function claim terms. Id. at 7. In particular, if the identified function of the claim is performed by a general-purpose computer or microprocessor, then the specification is required to disclose the algorithm the computer performs to accomplish that function, except in rare circumstances. Id. The structural examples linked to the function of “user identification module” were all “computer-readable media storage devices,” which the court concluded were nothing more than a general-purpose computer requiring an algorithm to control access to the software application packages. Id. at 8. Because no algorithm was disclosed to achieve the “control access” function, the court found the term “user identification module” lacked sufficient structure and rendered the claims indefinite. Id. at 9.