Aventis Pharma S.A. v. Hospira, Inc.

Intentionally withholding prior art material to the patent's subject matter from the Patent and Trademark Office will render a patent unenforceable for inequitable conduct.

Opinion (Prost): Aventis Pharmaceutical and Sanofi-Aventis (collectively “Sanofi”) sued Hospira, Inc., Apotex Inc. and Apotex Corp for infringing patents 5,750,561 (’561) and 5,714,512 (’512). The district court invalidated claim 5 of the ’561 patent and claim 7 of the ’512 patent, finding both claims obvious in light of prior art; and both patents unenforceable due to inequitable conduct because material information about the prior art was intentionally withheld from the Patent and Trademark Office (PTO). Sanofi appealed, arguing the district court erred in its construction of the claims, and in its determination that the information not disclosed to the PTO was material and intentionally withheld. The Court of Appeals agreed with the district court’s conclusion that claim 7 of the ’512 patent was obvious because Sanofi waived its argument against the district court’s construction by not addressing the issue in its opening brief. The Court of Appeals also agreed with the district court’s construction of claim 5 of the ’561 patent concerning the term “perfusion.” Lastly, accepting the district court’s determination that Sanofi’s witness did not have the credibility to overcome the fact that he withheld prior art that described the solution the patents implemented, the Court of Appeals AFFIRMED the district court’s judgment.