The Court of Appeals for the Federal Circuit, in what seems to be a confusion over neutralization of an acid versus a salt, held that a claim for an acid is not literally infringed by a salt in Kao Corp. and Andrew Jergens Corp. v. Unilever and Conopco.

Earlier, the U.S. District Court ruled that Kao’s U.S. Patent No. 6,306,382 was valid and enforceable but not infringed by Unilever’s accused product, Pond’s Clear Pore Strips – a cosmetic skin-care product used to remove “keratotic plugs” (a/k/a blackheads) from facial skin. The district court exercised jurisdiction pursuant to 28 U.S.C. § 1338.

Claim 1 recites as follows:

A method for removing keratotic plugs from skin with a cosmetic article, which comprises:
wetting the skin or said cosmetic article; applying onto the skin said cosmetic article; and peeling off said cosmetic article after drying; wherein said cosmetic article comprises: (i) a substrate selected from the group consisting of woven cloth, non-woven cloth and a plastic film; and (ii) on said substrate, a layer comprising a copolymer, in an amount effective to remove keratotic plugs, wherein said copolymer is a poly(alkyl vinyl ether/maleic acid) copolymer or a polyalkylvinyl ether/maleic anhydride) copolymer.

Claim 3 recites “The method of claim 1, wherein said substrate is a non-woven cloth.”

The district court also construed what it termed the “copolymer limitation” of claim 1 – the language stating “wherein said copolymer is a poly(alkyl vinyl ether/maleic acid) copolymer or a polyalkylvinyl ether/maleic anhydride) copolymer” to mean “either poly(alkyl vinyl ether/maleic acid) copolymer or poly(alkylvinyl ether/maleic acid anhydride) copolymer, but not the salt form thereof.” Concluding that “a salt copolymer is a distinct chemical entity from both an acid copolymer and an anhydride copolymer,” The court noted that after filing the application for the ‘382 Patent, Kao filed another application “with claims specifically directed to the salts of the copolymers claimed in the ‘382 patent.” The district court took this as evidence that the ‘382 Patent does not cover salt forms.

Kao argued that Unilever does not use the salt form of PVM/MA, but the acid form based on the fact that the addition of 2% AMP to the PVM/MA only slightly neutralizes the acid, such that “85.5% of the acid groups do not include a salt and only 14.5% of the acid groups include a salt.

The coating for the Pond’s strips is prepared by mixing 98% by weight of a solution of PVM/MA with 2% by weight of AMP. The AMP reacts with the PVM/MA to form what Unilever and the district court describe as a salt. The district court concluded that Unilever’s product did not literally infringe the ‘382 Patent because it did not meet the “copolymer” limitation of claim 1.

The Federal Circuit affirmed the lower court based on the belief that: was “uncontested” that there were “differences in chemical composition between the claimed PVM/MA and the PVM/MA acid-salt” used by Unilever’s product. Id. The primary difference was that Unilever’s product contains 98% by weight of PVM/MA copolymer and 2% by weight of AMP, which “reacts with the PVM/MA to form a salt.” Id. at 541. The trial court noted that “[t]he experts also agree that the claimed PVM/MA copolymer and the PVM/MA acid-salt have different chemical compositions which can be characterized by differences in their solubility, viscosity, and infrared spectra data.”

The court stated that “the relevant question is not whether Unilever’s compound is a salt, but whether it is “a salt form of” PVM/MA.” Huh? The Federal Circuit seemed to hang the decision on the fact that Kao offered no response to Unilever’s account of the record testimony beyond a conclusory assertion, unsupported by citation to the record, that Unilever’s account is “not correct.” [Note to practitioners: Get this evidence in the record!]

Judge Newman, concurring in part, dissenting in part contested the result saying “the panel majority has misunderstood the chemistry, in holding that neutralization of 14.5% of the maleic acid groups means that the totality is a salt and not an acid. This flawed science led to an incorrect conclusion of law.”

This decision seems to point out two critical items for patent holders. One, in drafting chemical patents, the drafter should spell out what is or is not a salt as well as what is an equivalent. And two, in an infringement action involving chemistry, you need to get the court educated on the reactions involved. Preferably, have the nuances spelled out in the specification. Kao also lost any chance for infringement under the doctrine of equivalents because it did not raise the issue, which seems odd given that the chemical changes effected by combining PVM/MA with AMP have no effect at all on the function of the invention.


A reader pointed out that Kao probably was sunk by its own patent application filed on the salt form. Because the district court determined that Unilever’s product used a salt, not the claimed acid, Kao could not meet literal infringement. Kao then tried to rely on Merck & Co. v. Teva Pharmaceuticals USA, Inc., 347 F.3d 1367 (Fed. Cir. 2003), for the proposition that “a claim that recite[s] an acid” may be “literally infringed by the salt of the acid” where “both the acid and its salt functioned similarly.” Kao argued that even Unilever does not dispute that the chemical changes effected by combining PVM/MA with AMP have no effect at all on the function of the invention.

However, the cited cases involve patent claims that were held to include salt forms. In the present case, the district court’s claim construction expressly excluded the salt form of PVM/MA. In addition, the court made note that Kao filed a separate application “with claims specifically directed to salts of the copolymers claimed in the ‘382 patent.” The Federal Circuit believed that if Kao had intended to claim salt forms of the copolymer in the ‘382 Patent, the subsequent patent application would have been superfluous. Therefore, by not filing on the salt forms in the original application, they may have given up any chance for a DOE claim.

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