CAFC Refines Function-Way-Result Test of Infringement

AIPLATalk208Applied Medical v. U.S. Surgical (Fed. Cir. 2006, 05–1314).

In a dispute over Applied Medical’s patented trocar, the district court granted summary judgment of non-infringement to U.S. Surgical. Specifically, the district court found that the recited means plus function language was not infringed.

A means plus function claim limitation is literally infringed when the relevant structure in the accused device perform the identical function recited in the claim and be identical or equivalent to the corresponding structure in the specification.

Once the relevant structure in the accused device has been identified, a party may prove it is equivalent to the disclosed structure by showing that the two perform the identical function in substantially the same way, with substantially the same result.

This test for infringement is known as the function-way-result test.  And, it was in applying the “way” portion of the test that the lower court erred.

Specifically, the district court looked at the “way” the accused structure operated in general and found that it was different from the “way” described in the specification.  The CAFC found this general approach to be wrong because it essentially imported additional limitations into the claims.

In this step, the inquiry should be restricted to the way in which the structure performs the properly-defined function and should not be influenced by the manner in which the structure performs other, extraneous functions. . . . [T]he district court improperly imported unclaimed functions when analyzing the way in which the disclosed embodiment performed the claimed function.

Summary judgment vacated.

2 thoughts on “CAFC Refines Function-Way-Result Test of Infringement

  1. Come on Bill, that would be too easy and make the law entirely too predictable. We can’t have any of THAT, now, can we?

    On a serious note, I like this decision and am begining to think that means-plus-function claims may have real value after all. Juries still get to decide what is an “equivalent” to the described corresponding structure. As far as I know, this is the only aspect of claim construction not entirely under the thumb of the Federal Circuit — though I imagine that “loophole” will ultimately be closed some day.

  2. I am so confused by this MFP “equivalent structure” quagmire. Why can’t we just go back to any means for accomplishing the claimed function?

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