CAFC: Claimed “Acid” Precludes Coverage for “Salts”

Kao CorporationKao Corporation v. Jergens Company (Fed. Cir. 2006, 05–1038).

by Bradley Crawford

This is a patent infringement case about removing “keratotic plugs,” i.e., blackheads, from facial skin. The claimed method encompasses a method for removing the keratotic plug by using a cosmetic article (not defined in the application but the “keratotic plug remover” is described in the specification as a “poultice” or a “cosmetic paste”), the method comprising 1) wetting the skin or the cosmetic article, 2) applying the cosmetic article to the skin and then 3) removing the cosmetic article after drying. The cosmetic article comprises 1) a substrate – essentially a backing material, and 2) a layer comprising a poly (alkyl vinyl ether maleic acid) copolymer or a poly(alkylvinyl ether maleic anhydride) copolymer.

The defendant’s product was used to remove blackheads and it contained the claimed poly(alkyl vinyl ether maleic acid) copolymer or a poly(alkylvinyl ether maleic anhydride) copolymer, but it also contained 2% by weight of aminomethyl propanol (a base that reacts with some of the acid groups in the copolymer).

The District Court construed poly(alkyl vinyl ether maleic acid) copolymer or a poly(alkylvinyl ether maleic anhydride) copolymer to not include the salt form of the copolymer because the “plain meaning” of the claims precluded salts. The District Court also relied on the fact that the patentee later filed an application specifically directed towards the salts of the copolymers claimed in the patent in suit – this was seen as evidence that the patent in suit did not cover salts. The CAFC also made note of this fact and relied on it.

(Note to all of the chemical patent drafters out there, if you are claiming compounds that contain acids or bases, you have to disclose and claim the corresponding salts. You just have to.)

Ultimately, the District Court found the patent to be valid and enforceable, but not infringed.

On appeal, the defendant argued the patent was invalid for: 1) lacking written description, 2) being obvious, and 3) inequitable conduct, while the patentee argued there was infringement. The CAFC rejected all of these arguments.

The District Court found there was written description for a claim amendment made by the patentee and the CAFC, while sympathetic to the patentee’s argument, found that the District Court’s judgment was not “clearly erroneous.”

The obviousness argument was based on a lack of “unexpected results.” More specifically, the defendant alleged both procedural and substantive arguments, including 1) the district court failed to use the closest prior art and 2) the district court failed to properly assess the “totality of the evidence.”

The inequitable conduct allegation was based on the patentees presenting only the most positive data to the Patent Office. The parties agreed that the non-disclosed material was material but the CAFC did not find the requisite intent because the missing data was eventually presented to the examiner. The CAFC was sympathetic to the defendant’s argument, but was unwilling to disturb the District Court’s decision as it was not abuse of discretion.

The CAFC also rejected the patentee’s infringement argument and distinguished two cases that stood for the proposition that “a claim that recites an acid may be literally infringed by the salt of the acid, where both have the same functionality.”

For an unexplained reason, the patentee did not assert infringement under the doctrine of equivalents.

Two concurring in part and dissenting in part opinions were also filed.

Bradley W. Crawford is a attorney at MBHB LLP focusing his efforts on patent litigation, prosecution, and counseling.  Prior to joining MBHB, Mr. Crawford worked in the areas of synthetic organic chemistry as well as medicinal chemistry. 

3 thoughts on “CAFC: Claimed “Acid” Precludes Coverage for “Salts”

  1. 3

    My first reaction to reading this case was incredulous. How can 2% by weight of AMP (a base) consume 98% by weight PVM/MA copolymer (an acid) to leave no residual acid? The claim clearly states that the patented compound is to “comprise”, in an amount effective to remove keratotic plugs, “a poly (alkyl vinyl ether/maleic acid) copolymer”.

    Then I read the judgment and saw that this may have been an attorney’s error at trial. The CAFC states that KOA’s argument that the acid was not fully neutralized by the base was “unsupported by the record or any other authority.” So much for relying on common general knowledge, including judicial awareness of basic high school chemistry.

    The other disturbing aspect of the CAFC ruling is the implication that because KAO applied for a subsequent improvement patent in which the salt was the active ingredient, this implied that the earlier patent in suit was intended to cover exclusively an acid. This suggests that it is dangerous to file for an improvement invention for fear that this will be used to read-down an earlier dominant patent claim.

  2. 2

    I’m a little confused. Acid + Base –> Salt + Water applies only to Bronstead acid/bases. The substituted amino base here is a Lewis base so I’m not even sure that a salt is being formed.

    I’m a chemist, not a lawyer, but I understand that you are your own lexicographer when writing a patent, so it may not be technically correct but legally correct.

    I also have to admit that I have only read the summary written by Bradley and not the patents or the opinion.

    John Spevacek
    Aspen Research, –
    “Turning Questions into Answers”

    Opinions expressed herein are my own and may not represent those of my employer.

  3. 1

    In the Kao case, with a 2% salt addition, wasn’t some of the polymer in the acid form and some in the salt form? If so, why not an infringement of the patent. I can accept that salts are different from acids and possilibty leading to an improvement and patentability? But, that shouldn’t be a bar to infringement.


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