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Noninfringement Ruling Subject to Further Fact-Finding

July 25, 2001

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Last Month at the Federal Circuit - August 2001

Judges: Gajarsa (author), Clevenger, and Rader

In Dow Chemical Co. v. Sumitomo Chemical Co., No. 00-1441 (Fed. Cir. July 25, 2001), the Federal Circuit vacated and remanded a district court’s grant of SJ, concluding that Sumitomo Chemical Company and Sumitomo Chemical America, Inc. (collectively “Sumitomo”) were not liable for infringement, either literally or under the DOE, of Dow Chemical Company’s (“Dow”) U.S. Patent No. 4,499,255 (“the ‘255 patent”).

The ‘255 patent improves upon a well-known process for preparing high-purity epoxy resins. These specific resins are often utilized in electrical applications and are particularly useful in the encapsulation of computer semiconductor chips. The high-purity epoxy resins are favored because they produce lower levels of hydrolyzable halide, which ultimately decreases the chances of computer chip failure. Since 1983, Sumitomo has utilized two different processes, the “old DOX” and the “new DOX,” to produce an epoxidation reaction. Both the old and the new processes consist of two stages, in which orthocreol novolac reacts with epichlorohydrin in the presence of a solvent (dioxane) to yield the desired result.

In 1996, Dow asserted a patent infringement action against Sumitomo alleging that both of Sumitomo’s processes fell within the scope of claim 1 of the ‘255 patent. On June 20, 2000, the U.S. District Court for the Eastern District of Michigan found that limitations regarding “boiling point” and “continuous” distillation present in claim 1 of the ‘255 patent were not found, either literally or under the DOE, in Sumitomo’s products.

On appeal, the Federal Circuit reexamined the determination of infringement by first analyzing the district court’s claim construction of independent claim 1. The Federal Circuit disagreed with the district court’s interpretation that the “boiling point” temperature is the temperature of the reaction mixture. Instead, the Court concluded that one of ordinary skill in the art would believe that the “boiling point” is measured in the vapor phase.

Furthermore, the Federal Circuit determined that there is no language in Dow’s specification to substantiate any other unconventional meaning for this term, and Sumitomo cited no technical treatise to refute the proposition. The Federal Circuit further stated that any alternative construction, other than the ordinary meaning, would exclude many of the preferred embodiments in the specification.

With regard to the construction of the terms “continuous” and “continuously,” the Federal Circuit ruled that the district court had improperly imported a limitation not supported by the claim language of the specification by requiring distillation that commenced simultaneously with the addition of alkali metal hydroxide.

After construing the claims, the Federal Circuit considered the infringement issue and found that the district court had incorrectly compared two stages of the Sumitomo processes with the ‘255 patent process. As a result, the Federal Circuit remanded this case to the district court to determine whether Sumitomo’s second stage alone may infringe.