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Explore the latest in patent, trademark, and copyright cases on the Merchant & Gould LLP blog. Stay informed with expert insights on intellectual property law updates.

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Recently, the U.S. Court of Appeals for the Federal Circuit issued an opinion in Maxell, Ltd. v. Amperex Technology Ltd., No. 2023-1194 (March 6, 2024), reversing a claim construction ruling by Judge Albright of the Western District of Texas. Maxell owns U.S. Patent No. 9,077,035 (the ’035 patent), directed to rechargeable lithium-ion batteries. Maxell filed an infringement lawsuit against Amperex, a Chinese manufacturer of lithium-ion batteries. In response, Amperex asserted that claim 1 of the ’035 patent was invalid as indefinite.

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The claim at issue requires at least two lithium-containing transition metal oxides, represented by formulas including a transition metal element M1. The relevant claim limitations read:

“M1&nbsp;represents at least one transition metal element selected from Co, Ni and Mn.”

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“Wherein the content of Co in the transition metal M1&nbsp;of the formulae (1) and (2) is from 30% by mole to 100% by mole.”

Following claim construction, Judge Albright’s Markman order found claim 1 to be indefinite because “the plain language of [claim 1] recites a contradiction.” That is: “[t]he first part of the claim recites a Markush group where [cobalt] is not necessarily required to be in the claimed compound while the second part of the claim recites that [cobalt] is necessarily required. For an element to simultaneously be optional and required is a contradiction on its face.” Judge Albright entered partial final judgment on claim 1 in favor of Amperex. Maxell appealed.

The Federal Circuit reversed and remanded. The Court found that claim 1 was not indefinite because the limitations in question were consistent. The Court held “[i]f there are two requirements, and it is possible to meet both, there is no contradiction.” The Court determined that limitation 2 narrowed limitation 1 rather than contradicting it. The first limitation states one requirement, i.e., a transition metal containing cobalt, nickel, or manganese. The second limitation states that the transition metal element must contain 30% to 100% cobalt by mole. Thus, it was completely possible for a transition metal element to meet both requirements.

The Court further noted that narrowing does not imply contradiction when it is done through dependent claims. Relying on Amperex’s concession at oral argument, the Court determined that there would be no contradiction if limitation 2 was written as a dependent claim. Accordingly, the Court reversed Judge Albright’s indefiniteness finding and remanded.

Federal Circuit Reverses Texas District Court’s Indefiniteness Finding

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