There seems to be a lot of controversy surrounding means-plus-function claims. From what I can gather a means-plus-function claim gives coverage to any methodology of achieving the prescribed claim so long as "the how" is described somewhere in the claims/specification.

Whereas a method claim would seem to be a way to specify how to achieve the steps for some hypothetical process - that might possibly be covered by a means-plus-function claim.

My question is what is the difference between the two? Are my statements above correct?

1 Answer 1


Functional claiming and claiming a method are two different constructs. A primary division of claim types are claims that define a thing and claims that define action steps for accomplishing something. A thing might be an apparatus, a machine, a system, a composition of matter, etc. A method or process claim is a list of actions or steps. They might be steps to make something or to use something but they are not the thing.

Means-plus-function can be used to define a structural element of a thing. "Means for fastening" is a sort of a placeholder for a thing. It would be whatever is contained in the collection of fasteners mentioned in the specification. It would not generally cover acts.

Functional claiming can be used in method claims. Instead of "means for" you would use "step for". An example would be "step for mixing oil and water".

Some inventions are inherently methods like a multi-step manner for getting rust off a metal tool; others are inherently a thing, like a composition of matter. Many inventions can be defined either in terms of a thing or a series of steps. A machine or system is a thing, but it also takes actions when when engaged. A claim for a machine would be infringed by a machine sitting on a shelf, in a box. A method claim to the operation of the same machine is infringed when the machine is plugged in, turned on, and operated.

If your invention lends itself to both thing claims and method claims, the choice is unrelated to any thoughts of functional claiming or not.

Also, functional claiming is an element-by-element issue. A claim could have five steps, three of which are spelled out in the claim and two of which could be functionally defined. One rule is that functional claiming can't be used for the only element of a single element claim.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .