Where non–disclosed prior art is insufficient to invalidate a patent by clear and convincing evidence, a question remains as to whether it is material under Therasense for inequitable conduct purposes if the art may have blocked issuance of one or more of the claims under the PTO’s preponderance of evidence standard and assuming the broadest possible construction of the claims.

American Calcar, Inc. v. American Honda Motor Co., Inc., 2009-1503, -1567 (Fed. Cir. June 27, 2011).

The patentee asserted 15 patents against the defendant for various aspects of computer systems in a car.  The court held three patents unenforceable for inequitable conduct, and on summary judgment, the court held one patent infringed and others not infringed.  A jury found the infringed patent not invalid, one group of the unenforceable patents not invalid, and another group invalid as anticipated by prior art.  The Federal Circuit affirmed in part, reversed in part, vacated in part, and remanded.

The findings of inequitable conduct were affirmed in part and vacated for reevaluation under the en banc decision in Therasense.  Regarding materiality, the panel upheld the district court’s findings for the patents the jury found anticipated by the non-disclosed prior art.  The panel also stated that even though other patents were found not anticipated by certain prior art, that same prior art could still be material for purposes of considering inequitable conduct.  Satisfaction of the lower preponderance standard used by the U.S. Patent and Trademark Office (PTO) during prosecution could justify a finding of materiality, even when a jury properly finds that the prior art would not meet the clear and convincing standard after issuance.

The panel also vacated and remanded the finding of intent because the district court used the old “sliding scale.”  Instead, the district court was directed to make specific findings on “whether any of the three inventors knew that withheld information was material and whether they made a deliberate decision to withhold it.” Slip Op. at 27.

In upholding the noninfringement rulings, the court affirmed a construction limited to examples in the specification where that limitation was emphasized as the core of the invention.  The court also affirmed the summary judgment of noninfringement under the doctrine of equivalence where the only evidence offered by the patentee was a broad declaration by an inventor that the accused device was similar.  Particularized testimony linking the insubstantiality of differences on a limitation-by-limitation basis is required to create a genuine issue for trial.

A copy of the opinion can be found here.