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“Uniform Flexible Film” Is Not Limited to Uniform Thickness

November 27, 2002

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Last Month at the Federal Circuit - January 2003

Judges: Rader (author), Clevenger, and Linn

In Middleton, Inc. v. Minnesota Mining and Manufacturing Company, No. 02-1151 (Fed. Cir. Nov. 27, 2002), the Federal Circuit reversed and remanded a SJ that U.S. Patent No. 4,944,514 (“the ’514 patent”) was not infringed, either literally or under the DOE. The Federal Circuit found that the district court had failed to correctly construe the claims and failed to determine whether prosecution history barred Middleton, Inc. (“Middleton”) from relying on the DOE.

Middleton owns the ‘514 patent, which is directed to a material for finishing the top surface of a floor. The claims of the ‘514 patent recite a floor covering having a “material for finishing” and a “uniform flexible film.”

Minnesota Mining and Manufacturing Company (“3M”) makes and sells a floorcovering product called Floorminders, which is applied to a smooth floor, but uses a textured surface film. Middleton sued 3M, alleging that the Floorminders product infringed the ’514 patent. The district court construed the phrase “uniform flexible film” to mean a film having a uniform thickness. However, the district court granted SJ of noninfringement based on a different claim limitation (“material for finishing”). In a previous decision, the Federal Circuit had found that the district court had erred in its claim construction of the phrase “material for finishing” and reversed the SJ of noninfringement. In that opinion, the Federal Circuit stated that the parties did not appear to dispute that the “uniform” limitation required a uniform thickness. On remand, the district court adopted this statement as its claim construction and granted SJ of noninfringement in favor of 3M, because the textured surface film of 3M’s Floorminders product did not have a uniform thickness. Middleton appealed for a second time.

The Federal Circuit found that the district court had erred in adopting this statement as its claim construction. Accordingly, the Court construed this phrase, de novo, based on the ordinary dictionary definition and the intrinsic evidence.

The Federal Circuit ruled that the most important indicator of the meaning of the “uniform” limitation was its usage in the context of floor coverings. In this context, that phrase encompassed a floor covering having the same form throughout. The Federal Circuit explained that many different types of floor surfaces may have varying thicknesses, but nonetheless, exhibit the same form throughout.

The Federal Circuit also considered the prosecution history of the ‘514 patent. During the prosecution of a related patent, the applicant asserted that the claimed uniform flexible film assured a uniform thickness required for the surfaces of bowling alleys. However, the Federal Circuit found that these assertions were limited to the context of bowling-alley surfaces and did not limit the broader claims of the ‘514 patent that were directed toward floor surfaces in general. Therefore, the Federal Circuit found that the “uniform” limitation as claimed in the ‘514 patent was entitled to an interpretation that included floor coverings having a consistent nonuniform thickness or other “uniform” irregularities.

The Court also commented on Middleton’s argument that contracts between 3M and its suppliers permitting manufacturing tolerances should be used as evidence in construing the patent terms in the claims. The Federal Circuit emphasized that the meaning of patent terms depends on the usage of those terms in context by one of skill in the art at the time of application. It noted that a contract may supply some insight into the understanding of skilled artisans at the time of invention, but that no such evidence had been offered.

The Federal Circuit also found that the Supreme Court’s decision in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 122 S. Ct. 1831 (2002), required the district court to consider infringement under the DOE.