Acid Claims Not Infringed By Partly Neutralized Acid

In Kao Corp., et al. v. Unilever United States, Inc., et al. (No. 05-1036, -1049; March 21, 2006), a Federal Circuit panel affirms a trial court's holding that Kao's patent is valid and enforceable but not infringed. The trial court interpreted Kao's claim to cover the acid forms of a copolymer and to exclude the salt forms of the copolymer. This claim construction was based, in part, on Kao's filing of another application directed to the salt form. The trial court took this filing as evidence that the patent in suit did not cover salt forms of the copolymer.

Unilever's accused infringing product included the claimed copolymer, but it was partially neutralized into the salt form. Unilever argued that it uses the salt form of the copolymer, and the Federal Circuit panel determines that Kao failed to rebut this assertion, other than offering an unsupported conclusion that Unilever uses a slightly neutralized acid and not a salt. Addressing Kao's argument that even if Unilever uses a salt it still infringes the claims, the panel distinguishes cases where an acid claim was infringed by a salt because in those cases the claims included the salt. Judge Newman dissents, pointing out that neutralizing 14.5% of the acid groups in the copolymer does not yield a salt and also that the record supports Kao's argument that Unilever uses a slightly neutralized acid.