Federal Circuit Rejects “Unanswered Questions” Indefiniteness Standard

By Emily Parker and David Barker

Last week, a split Federal Circuit panel reversed a decision invalidating certain computer-aided-design patent claims because the district court used an incorrect indefiniteness standard.

Nature Simulation Systems (“NSS”) sued Autodesk, Inc. for infringing two patents directed to computerized methods for building three-dimensional objects. Autodesk argued that certain claims in NSS’s patents were indefinite under 35 U.S.C. § 112. During a claim construction hearing, the district court held the claims were indefinite – and therefore invalid – because there were various “unanswered questions” raised by the claims’ terms. The district court held that such “unanswered questions” render a claim indefinite as a matter of law, even if the specification answers those questions. NSS appealed.

The Federal Circuit reversed in a 2-1 decision, with the majority holding that the district court’s “unanswered questions” analysis applied the incorrect standard for indefiniteness. The majority explained that a claim is viewed and understood not solely on what is written in the claim, but also in the context of “the specification, the prosecution history, and extrinsic evidence concerning relevant scientific principles, the meaning of technical terms, and the state of the art.” First, the majority recognized there was no dispute that the specification describes and enables practice of the claimed method, including the best mode. Second, the majority found the prosecution history particularly significant because a patent examiner initially rejected the claims at issue as indefinite by pointing out unanswered questions, but ultimately withdrew the indefiniteness rejection after certain recommended amendments. The majority criticized the lower court for failing to give appropriate deference to the examiner’s analysis and approval of the amendments. The court ultimately concluded that indefiniteness was not established as a matter of law, and it remanded the case for further proceedings under the appropriate standard.

Judge Dyk dissented, arguing that the majority was “manifestly incorrect” in reversing the lower court’s decision. According to Judge Dyk, the lower court did not apply an “unanswered questions” standard as the majority suggests, but instead “read the patent’s claims in light of the specification to determine if it would inform those skilled in the art about the scope of the invention with reasonable certainty, which is exactly what is required[.]” Judge Dyk faulted the majority for relying so heavily on prosecution history, reasoning that the test for indefiniteness is “not whether the claim language was added by a patent examiner or was not indefinite to the examiner,” but whether it informs those skilled in the art. The majority responded to this criticism by noting that an examiner is presumptively a person of skill in the art.

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