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No Equivalents Found Where Court Relied Upon Unclaimed Features And Patentee Did Not Present Particularized Testimony Regarding Equivalents

Client Alert | 2 min read | 02.28.07

In AquaTex Industries, Inc. v. Techniche Solutions (No. 2006-1407; February 27, 2007), a Federal Circuit panel affirms the district court’s decision granting summary judgment of non-infringement to Techniche Solutions, but holds the district court erred in finding the doctrine of equivalents barred by prosecution history estoppel and in relying upon unclaimed features to find a lack of equivalents. AquaTex sued Techniche for infringement of its ‘977 patent. The claim limitation at issue concerns the language “fiberfill batting material”. With regard to the district court’s ruling that the doctrine of equivalents is barred by prosecution history estoppel, this panel states that the district court’s approach is foreclosed by the Court’s previous opinion which holds that the subject matter which was surrendered by the narrowing amendment bears no relation to the composition of the fiberfill batting material claim limitation. The Federal Circuit concludes as the amendment was directed to a completely separate claim limitation, AquaTex did not surrender any claim to the characteristics of the fiberfill batting material during prosecution and is therefore, not barred from asserting equivalents to the fiberfill batting material claim limitation.

In further considering the doctrine of equivalents analysis, the panel states that the function, way, result test focuses on an examination of the claim and on the explanation of that claim in the written description. The panel notes that the district court appears to have concluded that the function of the “fiberfill batting material” is to promote evaporation, which was determined from information displayed on AquaTex’s website. The Federal Circuit holds that this reliance on the characteristic of the patentee’s product was erroneous and that infringement, either literally or under the doctrine of equivalents, does not arise through a comparison of the accused product with a commercialized embodiment of the patentee.

Addressing the district court’s ruling of summary judgment de novo, the panel states that under the doctrine of equivalents a patentee must present particularized testimony and linking argument as to the insubstantiality of the differences between the claimed invention and the accused device or process and such evidence must be provided on a “limitation-by-limitation” basis. The panel notes that the complexity of this doctrine requires that the evidence be presented through the testimony of a person of ordinary skill in the art, 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. The Federal Circuit concludes that AquaTex did not provide any particularized testimony from an expert or one of ordinary skill in the art that addresses the equivalents on a “limitation-by-limitation” basis, as the only evidence presented by AquaTex on the issue of equivalents was lawyer argument and generalized testimony, from Techniche’s Executive Officer, concerning the accused product.

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Client Alert | 8 min read | 06.30.25

AI Companies Prevail in Path-Breaking Decisions on Fair Use

Last week, artificial intelligence companies won two significant copyright infringement lawsuits brought by copyright holders, marking an important milestone in the development of the law around AI. These decisions – Bartz v. Anthropic and Kadrey v. Meta (decided on June 23 and 25, 2025, respectively), along with a February 2025 decision in Thomson Reuters v. ROSS Intelligence – suggest that AI companies have plausible defenses to the intellectual property claims that have dogged them since generative AI technologies became widely available several years ago. Whether AI companies can, in all cases, successfully assert that their use of copyrighted content is “fair” will depend on their circumstances and further development of the law by the courts and Congress....