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Lack of Antecedent Basis Not Grounds for Invalidity If Claim Can Be Construed

January 25, 2006

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Last Month at the Federal Circuit - February 2006

Judges: Newman (author), Archer, and Schall

In Energizer Holdings, Inc. v. International Trade Commission, No. 05-1018 (Fed. Cir. Jan. 25, 2006), the Federal Circuit reversed the ITC’s holding of invalidity for indefiniteness under 35 U.S.C. § 112, ¶ 2, and remanded the case for further proceedings.

The patent at issue, U.S. Patent No. 5,464,709 (“the ’709 patent”), is for an electrolytic alkaline battery cell that is substantially free of mercury. These so-called “zero-mercury-added” batteries stem from the discovery that zinc, used for the battery’s anode, contains trace impurities. Identifying and eliminating those impurities precludes the need to add mercury, a corrosion inhibitor, to the battery cell. As mercury is an environmental pollutant, extensive effort has been devoted to reducing or eliminating the mercury content in alkaline batteries.

Energizer Holdings, Inc. and Eveready Battery Company, Inc. (collectively “EBC”) charged the respondents with violation of 19 U.S.C. § 1337 based on their importation into the United States, sale for importation, and sale within the United States of batteries asserted to infringe the ’709 patent. Claim 1 of the patent recited “[a]n electrochemical cell comprising . . . an anode gel comprised of zinc as the active anode component, wherein the cell contains less than 50 parts ofsaid zinc anode has a gel expansion of less than 25% after being discharged for 161 minutes to 15% depth of discharge at 2.88A.” Slip op. at 5.

The ITC held invalid independent claim 1 and dependent claims 2-7 for lack of antecedent basis of the phrase “said zinc anode.” Moreover, the ITC held that even if “said zinc anode” was construed to have as antecedent the “anode gel comprised of zinc as the active anode component” recited earlier in the claim, the claim would still be indefinite as written because it required that the anode of every cell be “discharged for 161 minutes to 15% depth of discharge at 2.88A.” The ITC reasoned that since the discharge parameters were intended to apply to only a test cell and not to every cell, the claim drafting was ambiguous and rendered the claim indefinite. In addition, the ITC held that EBC’s proffer of alternative constructions of “said zinc anode” was an admission of indefiniteness.

EBC argued the claims were not “insolubly ambiguous” and that a person of ordinary skill in the art would understand the claim because the specification made clear that the test parameters included in the claim did not mean that every cell must be discharged for 161 minutes. EBC pointed out that the ’709 patent was directed to a standard electrolytic alkaline cell, and the specification clearly stated the purpose of the test was to identify zinc anode material used in the invention.

The Federal Circuit agreed and reversed the determination of the ITC. The Court reasoned that despite the lack of explicit antecedent basis for “said zinc anode,” whether the claim had a reasonably ascertainable meaning must be decided in context. In agreeing with EBC that the claims could be construed, the Federal Circuit pointed out that, in prosecuting the ’709 patent, the Examiner made several objections to the claims, but the claims were neither rejected nor objected to on the ground of lack of antecedent basis. The Court noted that an antecedent basis can be present by implication. Furthermore, neither the ITC nor Eveready argued that they did not understand the intended scope because of the absence of an antecedent.

The Federal Circuit also held that the ITC had erred in holding that the need to construe a claim, or the proffer of alternative constructions, rendered the claim indefinite. The Court thus reversed the ITC’s holding of invalidity, concluding that the claim was amenable to construction and that “anode gel” was by implication the antecedent basis for “said zinc anode.”