Preliminary stuff
Means-plus-function claiming is a way of writing a patent that describes what something does, not how it does it. For example, describing a machine that opens a jar, rather than describing all the parts- a motor, a gripper, and how they work together, you just say: “A means for opening a jar”. This is to say you want to protect whatever part does the opening of the jar, without naming the exact part.
However, the actual parts, the structure, must be described elsewhere in the patent. This is a way to write less in the claims, but the downside is if it doesn’t describe how it works well enough, the claim might be invalid.
Section 112(f) addresses means-plus-function claiming. The courts have a two-step analysis for such claims. First, determine whether the claim limitation is drafted in a means-plus-function format, which would invoke Sec 112(f). Second, if it is, identify what structure, if any, disclosed in the specification corresponds to the claimed function.
In any cases lacking disclosed structure, the claim is invalid under Sec 112(b), dealing with claim definiteness. In simple terms, a patent must clearly tell others what is being claimed so they know the boundaries of the invention. Clear claims can be understood, competitors can avoid infringement, and courts can enforce the patent consistently.
Vague or ambiguous claims can be ruled invalid for indefiniteness, which is especially relevant in means-plus-function claims. If the patent application doesn’t describe the structure that performs the function, it may be invalid.
Fintive v. PayPal
In a significant ruling that reinforces the high bar for software claim clarity, the Federal Circuit recently affirmed the invalidation of several Fintiv, Inc. patents due to indefiniteness. The decision in Fintiv, Inc. v. PayPal Holdings, Inc. (No. 2023-2312, Apr. 30, 2025) is a clear message to patent drafters: functional language in software claims needs structural backing—or risk getting wiped out under 35 U.S.C. § 112.
The Core Issue: Functional Terms with No Structure
At the heart of the case were terms like “payment handler” and “payment handler service,” found in Fintiv’s asserted patents. These terms were intended to cover components that interface with various payment APIs. But the court found they lacked inherent structural meaning and instead described what the component does rather than what it is.
This triggered the court’s application of the means-plus-function analysis under § 112(f)—even though the word “means” wasn’t used.
Why Fintiv Lost
Fintiv tried to argue that “payment handler” had a recognized meaning in the art, citing dictionaries, examples from the patent, and even the Internet Open Trading Protocol. But the court was unconvinced. It found that these terms merely recited functions—such as wrapping APIs or exposing common interfaces—without explaining how the functions were implemented. Essentially, “payment handler” was treated like a black box.
The specification didn’t help either. Instead of disclosing a specific algorithm or structure, it restated the functional goals. According to the court, that’s not enough under § 112(f). A person of ordinary skill in the art (POSA) wouldn’t be able to implement the invention based solely on the description provided.
So functional terms, even if they sound technical, can lead to invalidation if the specifications don’t back them up with a structure, which for software patents, usually means an algorithm. It should also remind you that just because you avoided the word ‘means’ doesn’t mean you’ve avoided ‘means-plus-function’ treatment. The court will look at substance, not just form.