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Noninfringement Measured in Thousandths of a Gram

July 31, 2001

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Last Month at the Federal Circuit - August 2001

Judges: Newman (author), Lourie, and Rader

In Viskase Corp. v. American National Can Co., No. 99-1569 (Fed. Cir. July 31, 2001), the Federal Circuit affirmed-in-part, reversed-in-part, and remanded a district court judgment, following a jury trial, of willful infringement. The issues on appeal involved the claim construction of density ranges and the term “linear,” the grant of SJ of infringement under the DOE, and the grant of JMOL that all patents-in-suit are valid.

Viskase Corporation (“Viskase”) charged American National Can Company (“ANC”) with infringement of six of its patents. The Viskase patents are directed to heat-shrinkable films used to make plastic bags for packaging food. The patentsin- suit were classified as “first family” and “second family” patents. The first family patents include U.S. Patent Nos. 4,863,769; 4,976,898; 5,059,481; and 5,256,351. These patents relate to outer-film layers of very low density polyethylene copolymers (“VLDPE”) and claim a density limited to “below about 0.91 g/cm3.” The second family patents include U.S. Patent Nos. 4,863,784 and 4,988,465. These patents also use VLDPE in the outer-film layers and the claims recite a density “not greater than about 0.915 g/cm3.”

The ANC products accused of infringement are heat-shrinkable films having either a linear ethylene copolymer with a density of 0.912 g/cm3 ( “Attane” copolymer) or an ethylene copolymer having a density of 0.908 g/cm3 ( “Affinity” copolymer) and a MA-saran core.

The issue of infringement turned on the scope of the densities of VLDPE encompassed in “below about 0.91 g/cm3” for the first family patents and “not greater than about 0.915 g/cm3” for the second family patents. Also at issue for the second family patents was the degree of branching of the VLDPE.

For the first family patents, the district court had construed the term “about 0.91 g/cm3” to include numbers that would be rounded to 0.91, i.e., between 0.905 g/cm3 and 0.914 g/cm3, despite arguments that the prosecution history limited the density term to “below about 0.910 g/cm3.” Based on its construction, the district court had granted SJ that ANC’s products containing the Attane copolymer literally infringed the first family patents.

On appeal, the Federal Circuit found Viskase’s prosecution history to be highly relevant. Of particular interest was a statement in which Viskase distinguished its products from a prior art reference that taught densities of 0.910 to 0.940 g/cm3 by stating that the “A” copolymer was not pertinent to the present application in that it does not have a density “below about 0.910 g/cm3” as defined in all pending claims. The Court therefore construed the density term of the first family patents of “below about 0.91 g/cm3” to mean “below about 0.910 g/cm3.” Based on the Court’s corrected claim construction there could be no literal infringement by products containing the Attane copolymer, whose density is 0.912 g/cm3, and therefore, the Court reversed the judgment of literal infringement of first family  patents by such products.

In the second family patents, the VLDPE used has a density of “from about 0.850 to about 0.915 g/cm3.” As no arguments were presented by ANC, the Court, on the plain reading of the claims, affirmed the grant of SJ of infringement of the second family patents by the ANC products containing the Attane copolymer (density of 0.912 g/cm3).

For the ANC products containing the Affinity copolymer (density of 0.908 g/cm3), the infringement issue turned on whether the Affinity copolymer was “linear.” The parties agreed with the district court’s construction of the term “linear” as meaning “without significant long chain branching,” but disagreed as to the meaning of “significant.” At trial, the jury had found literal infringement of both families of patents by the products containing the Affinity copolymer. However, based on subsequently discovered perjury of one of Viskase’s expert witnesses, the district court had vacated the judgment of literal infringement and granted a new trial. The district court had then reversed itself, granting Viskase’s motion for SJ of infringement by Affinity copolymer products under the DOE and vacating the new trial order.

On appeal, the Federal Circuit found that the district court’s grant of SJ was inappropriate. ANC had proffered evidence that the Affinity copolymer has significant long-chain branching in its molecular structure. ANC had also proffered evidence of advantages associated with its products and attributed to the nonlinear nature of the Affinity copolymer. ANC had argued, and the Court agreed, that a reasonable jury could have found that these were not insubstantial differences. Thus, the issue requires a trial.

The Court also considered the district court’s judgment of validity of the patents-in-suit. The district court had granted JMOL that the six patentsin- suit were valid. On appeal, ANC challenged the district court’s grant of JMOL and the merits of the judgment.

On appeal, ANC cited references in addition to those that were before the district court. However, because ANC did not present any compelling reason to consider references that were available during the pretrial period, the Court declined to consider the new arguments. The Court also found that the record showed that the district court had received full argument on the issues of validity and that ANC provided no evidence of a suggestion, teaching, or motivation in the prior art cited by ANC to combine the references as suggested by ANC. For these reasons, the Court affirmed the district court’s grant of JMOL, upholding the validity of the patents-in-suit.

After the district court’s finding of validity of the patents-in-suit, ANC filed a request for reexamination in the PTO patent from each family. During the reexamination process, Viskase petitioned the PTO to correct inventorship for the second family patents. The PTO granted the petition. Based on the inventorship change, ANC moved the district court to reopen the judgment and dismiss the infringement counts as to the second family patents and filed a separate DJ action seeking to invalidate the second family patents based on alleged irregularities in the process of correcting inventorship. The Federal Circuit found no flaws in the district court’s dismissal of the declaratory counts as raising no new issues.