Plaintiffs: Get Expert Testimony Before Summary Judgment

ScreenShot024AquaTex Indus. v. Techniche Solutions (Fed. Cir. 2007).

AquaTex owns a patented multi-layered, liquid-retaining material used in evaporative cooling garments. Techniche is accused of infringement.

In an earlier decision, the CAFC asked the lower court to examine whether Techniche’s products infringed under the doctrine of equivalents (DOE).  And again, the district court found that the DOE could not extend the AquaTex patent to cover Techniche’s activities — holding that (1) a narrowing amendment during prosecution estopps AquaTex from asserting the DOE and (2) AquaTex failed to prove that the asserted equivalent (filler layer) performs “substantially the same function in substantially the same way” as the patented method.

Prosecution History Estoppel: “The surrender of subject matter during prosecution creates a presumption that the patentee is precluded form recapturing that subject matter through the doctrine of equivalents; this presumption can be rebutted by . . . a showing that the amendment was unrelated to patentability.” 

DOE is executed on an element-by-element bases, and, taking a step back, CAFC noted (for the second time in this case) that estoppel only applies if the narrowing amendment bears a direct relation to the alleged equivalent element. Here, there was no direct relationship because the amendment “was directed to a completely different claim limitation.”

Thus, the district court erred in applying prosecution history estoppel

Function-Way-Result: The standard test for infringement under the doctrine of equivalents requires that each element of the asserted claim either be infringed literally or under the DOE. An element infringes under the DOE if claimed element differes insubstantially from the accused product or if the asserted element performs the substantially same function in substantially the same way with substantially the same result.

The meaning of “substantially the same” is informed both by the claim language and the specification itself. However, the inquiry “leaves no room for consideration of the patentee’s product.” Here, the lower court used the patentee’s description of the product on its website to determine that the function of the claimed filler layer element included hydrophobic activity.  That was an error because it shifted the focus from the patent to the product.

Evidence: Finally, for a patentee to win on DOE, it must present “particularized testimony and linking argument on a limitation-by-limitation basis” showing equivalence. The gold-standard for this evidence is the testimony of a qualified PHOSITA — “typically a qualified expert, who (on a limitation-by-limitation basis) describes the claim limitations and establishes that those skilled in the art would recognize the equivalents.”

Here AquaTex had only provided lawyer argument and generalized testimony about the accused product. The CAFC found the evidence lacking and thus that the defendant should be awarded summary judgment of non-infringement.


  • Does anyone know if expert reports had been submitted yet in this case?
  • Read the case

3 thoughts on “Plaintiffs: Get Expert Testimony Before Summary Judgment

  1. 3

    “Qualified” in this case is a term of art. Before someone can testify as an expert, he or she must be “qualified,” which means that the court determines whether the person is actually an expert.

  2. 1

    PACER doesn’t contain any mention of an expert report filed. There are several references to experts, expert affidavits in support of a motion for summary judgment, and expert disclosures, but no clear indication that an expert report was filed.

    Additionally, M.D. Tenn.’s PACER system doesn’t have any documents from before mid-2005, so it’s hard to do much poking around beyond reading the docket report.

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