Indefiniteness Is Not Determined by the Claim Language Alone

| Justin J. Gillett


Before Newman, Lourie, and Dyk. Appeal from the United States District Court for the Northern District of California.

Summary: It was improper for the district court to find patent claims indefinite without considering the specification and prosecution history.

Nature Simulation Systems, Inc. (“NSS”) sued Autodesk, Inc. alleging patent infringement. After a claim construction hearing, the district court found various claims invalid as indefinite. The district court recited several “unanswered questions” about terms in those claims and stated that such unanswered questions render a claim term indefinite as a matter of law, even if the specification answers those questions. NSS appealed.

The Federal Circuit reversed in a 2-1 decision. The majority held that the district court’s analysis involving “unanswered questions” applied an incorrect standard for indefiniteness. The majority emphasized that patent claims are viewed in light of the specification, the prosecution history, and other relevant evidence, and it faulted the district court for relying on the claim language alone. The majority noted that, during prosecution, indefiniteness rejections had been resolved by adding limitations to the claims, including by examiner’s amendment. After also considering the specification, the majority concluded that the claim terms at issue were not indefinite.

Judge Dyk dissented, arguing that the district court had read the patent claims in light of the specification and had properly determined the claim terms at issue were indefinite. According to Judge Dyk, the specification does not explain certain claim limitations that the patent examiner suggested during prosecution, and the majority improperly relied on the fact that the examiner suggested those terms instead of requiring that the specification explain them.

Editor: Paul Stewart