Defining Indefiniteness: When Are Claim Limitations Contradictory?

Written by: Alistair J. McIntyre & Jeremy Anapol

MAXELL, LTD., V. AMPEREX TECHNOLOGY LIMITED

Before Prost, Taranto, and Chen. Appeal from the United States District Court for the Western District of Texas.

Summary: Two claim limitations are not contradictory if they can be satisfied simultaneously.

Maxell asserted that Amperex infringed its battery patent. Amperex challenged the validity of the patent, alleging that the claims were indefinite under 35 U.S.C. § 112 for reciting (1) “wherein M¹ represents at least one transition metal element selected from [cobalt, nickel, or manganese]” and (2) “wherein the content of [cobalt] in the transition metal M¹ . . . is from 30% by mole to 100% by mole.” At claim construction, the district court agreed that limitations (1) and (2) were contradictory and therefore indefinite. The district court reasoned that the claim language was contradictory because limitation (1) only optionally required cobalt, but that limitation (2) necessarily required cobalt. Maxell appealed.

The Federal Circuit found that limitations (1) and (2) were not contradictory and therefore not indefinite. The court reasoned that a transition metal element could both contain cobalt, nickel, or manganese and include 30% by mole to 100% by mole of cobalt.  Thus, the Federal Circuit reversed the district court’s judgment.

Editor: Sean Murray