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Basically, the question is: does one get free disjunction with means-plus-function claim limitations?

In other words, if the claim recites "means for fastening", and the specification contains:

  • As will be readily appreciated by those skilled in the art, a screw provides a means for fastening.

  • As will be readily appreciated by those skilled in the art, glue provides a means for fastening.

(A) Is this a valid way to get a claim with approximately the same coverage as "screw or glue" would have at the point where "means of fastening" is recited, if it were permitted to have a disjunction in a claim?

(B) Is it a good approach to recite multiple different structures as providing the "means" as is done above, or should there be only one "anchoring site" for the "means" with the different possibilities combined simply with "or"?

(C) Are there any other caveats to be aware of?

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Alternatives are permitted in claims. One way is just with the word "or". Another way is via a so-called Markush group. "and fastened with at least one item from the group including screw, nail, glue, and, rivet . . .".

One worry about alternatives is alternatives on top of alternatives and other limitations in a claim that might pertain to some alternatives but not to others.

Yes, you can use means + function to include everything clearly stated as a structure to achieve the means that is set forth in the application-as-filed, and equivalents within the meaning set forth in case law. M+F claims have their own history of judicial interpretation. I would us M+F in parallel with other claims of similar scope that did recite structure.

If structure is actually required - the limitation that thing1 is securely attached to thing2 with location X mated to location Y might be all you want to say. A lot of "ors" in not mentioning the "means" at all.

The caveat is good claims that hold up, are hard to design around, and say what you think they say are very hard to draft.

From a law firm article about or, and, and or/and -

Another example shows the importance of carefully choosing alternative language when drafting claims. In Kustom Signals, Inc. v. Applied Concepts, Inc.,5 Kustom Signals added the limitation “selecting either a greatest magnitude or highest frequency search” to the claim during prosecution and later sued Applied Concepts for patent infringement. But Applied Concept’s device searched both magnitude and frequency. The Federal Circuit reasoned that “or” is not “and/or” and the claim only covered a choice between either one of two alternatives, not both. The Court then affirmed a ruling of noninfringement by Applied Concept’s device. The outcome was indeed unfortunate for Kustom Signal, but it could have avoided the problem by carefully drafting the claim to read, for example, “selecting at least one of a greatest magnitude search and a highest frequency search.”

If this holds, using both some screws and some glue is not infringed by "screws or glue".

A suggested library -

Essentials of Patent Claim Drafting

Invention Analysis

Rules of Patent Drafting: Guidelines from Federal Circuit Case Law; 2017

Landis on Mechanics of Patent Claim Drafting

And keeping up with developments in the courts and at the USPTO via blogs, PatentlyO, for example.

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  • I'm a retired patent agent who hasn't kept up myself as carefully as I did when I was practicing.
    – George White ♦
    Commented Feb 7 at 2:36
  • "One way is just with the word "or". Another way is via a so-called Markush group." Up to now I thought "or" was not allowed, and Markush groups are a narrow exception to the rule. But it seems the latest MPEP says "or" is simply treated as if it were a written out Markush group (MPEP 2117 - any claim that recites alternatively usable members, regardless of format, should be treated as a Markush claim). To the extent that all the recitations of structure supporting a 112(f) claim limitation must be capable of performing the means function it would seem they would usually form a Markush group.
    – bhuff36
    Commented Feb 7 at 3:52
  • The case law history/pitfalls for Markush and M+F are separate bodies of law with their own exceptions to the exceptions. Note my addition of a problem with or not taken to mean and/or. It's from the early 2000's and may or may still hold.
    – George White ♦
    Commented Feb 7 at 5:15
  • Sure, Markush and M+F are separate, but my main point was I realized that M+F does not buy a great deal of additional generality in what can be claimed over a Markush-type claim, though the "equivalent" Markush claim may be very long and awkward to phrase for a typical M+F usage.
    – bhuff36
    Commented Feb 7 at 16:32
  • Regarding the "or" case, I think the problem there is the patentee had a machine that can do either one of two things (disjunctive behavior of machine), and this is handled differently than disjunction between two claim limitations. Under a "comprising" preamble, I would expect "or" to still always behave like "and/or" because the claim having "or" captures in two different ways a device having "and" (though I have not researched this thoroughly).
    – bhuff36
    Commented Feb 7 at 16:47

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