The two-step analysis for means-plus-function language for patent claims is set forth in Williamson v. Citrix Online, LLC, 792 F.3d 1339 (Fed. Cir. 2015). First, determine whether the claim limitation is drafted in means-plus-function format, invoking § 112(f). Second, if it is, identify what structure, if any, disclosed in the specification corresponds to the claimed function. See Egenera, Inc. v. Cisco Sys., Inc., 972 F.3d 1367, 1372–73 (Fed. Cir. 2020). Finally, in cases lacking any disclosed structure, the claim is found invalid as indefinite under § 112(b). Connecting terms such as “that,” “operable to,” and “configured to” describe functions, not impart structure.

The Federal Circuit recently held that the claim term “payment handler” recited function without sufficient structure for performing that fucntion. Fintiv, Inc. v. PayPal Holdings, Inc., No. 2023-2312, __ F.4th __ (Fed. Cir. Apr. 30, 2025). Relating to a “cloud-based transaction system,” also referred to as “mobile wallet platform,” the patent claimed "a payment handler service operable to use [application programming interfaces or APIs] of different payment processors including one or more APIs of banks, credit and debit cards processors, bill payment processors"; "a payment handler configured to use APIs of different payment processors including one or more APIs of banks, credit and debit cards processors, and bill payment processors"; and "a payment handler that exposes a common API for interacting with different payment processors." 

The Federal Circuit found that the payment-handler terms were “drafted in a format consistent with traditional means-plus function limitations” and merely replaced ‘means' with ‘payment handler.'” The Court affirmed that the district court had correctly analogized “handler” with the nonce term “module,” which was “simply a generic description of software or hardware that performs a specified function.” Williamson, 792 F.3d at 1350; see also Rain Computing, Inc. v. Samsung Electronics America, Inc., 989 F.3d 1002, 1006 (Fed. Cir. 2021) (concluding that “user identification module” invoked § 112 ¶ 6). Furthermore, the connecting term “configured to” does not necessarily avoid means-plus-function claiming. Rain Computing, 989 F.3d at 1006. In addition, as used in the claims, the payment-handler terms were no more than a black box recitation of structure that can operate as a substitute for “means.” Williamson, 792 F.3d at 1350, compare with Apple Inc. v. Motorola, Inc., 757 F.3d 1286, 1303 (Fed. Cir. 2014)(“the claim language and specification outline[d] the rules that the [claim term] follow[ed],” so the claim language provided sufficiently definite structure and the patent “recite[d] a claim term with a known meaning.”). Here, the claims and specifications, including the figures in the asserted patents, did not provide sufficiently definite structure to the “inputs, outputs, connections, and operation” of the payment-handler terms. 

Proceeding to the second step of the analysis, namely, identifying the corresponding structure described in the specification; the Court concluded that the specifications of the asserted patents do not disclose any algorithm to perform the recited function, and that "Fintiv's purported two-step algorithm merely recites the asserted claims' language." It was not enough to recite the function of the payment-handler terms using generic terms without providing any details about an algorithm to carry out the functions of using APIs of different payment processors including one or more APIs of banks, credit and debit cards processors, bill payment processors, and exposing a common API for interacting with different payment processors.

[D]escribing “the results of the operation of an unspecified algorithm” is not sufficient to transform the disclosure of a general-purpose computer into the disclosure of sufficient structure to satisfy § 112 ¶ 6. Aristocrat Techs. Austl. Pty Ltd. v. Int'l Game Tech., 521 F.3d 1328, 1335 (Fed. Cir. 2008). Without an algorithm to achieve these functionalities—and, more generally, given the specifications' failure to disclose adequate corresponding structure—we hold the payment-handler terms indefinite. 

Because the specifications merely refered to the generic process of translating APIs, and a person of ordinary skill in the art would not understand where the wrapping of the APIs occur, the Court affirmed that the claims were invalid as indefinite.