In Rain Computing, Inc. v. Samsung Electronics Co., Ltd., the Federal Circuit reversed the district court’s determination that “user identification module” was not indefinite.

The Federal Circuit first analyzed whether “user identification module” is a means-plus-function term. For terms not including “means for” language, the term will only be construed as means-plus-function if it recites a function without sufficient structure for performing the function. The Federal Circuit found the term was a means-plus-function term because Rain failed to identify claim language that provided the structure for performing the claimed function and that the term itself “merely describe[ed] the function of the module: to identify a user.” Slip op. at 5.

The analysis next turned to identifying the function and corresponding structure in the specification, consistent with procedures for construing means-plus-function terms. Under relevant precedent, “[w]here a general-purpose computer is the corresponding structure and it is not capable of performing the controlling access function absent specialized software,” the patent must disclose an algorithm for performing the claimed function. Id. at 9. Because no algorithm could be found, the Federal Circuit held that the term “user identification module” lacked sufficient structure, rendering the claims indefinite.