An applicant’s earlier statements about prior art, especially one’s own prior art, are material to the PTO when those statements directly contradict the applicant’s position regarding that prior art in the PTO.

Therasense, Inc. v. Becton, Dickinson and Co., No. 2008-1511, -1512, -1513, -1514, -1595 (Fed. Cir. Jan. 25, 2010)

The patentee sued alleging infringement of three patents covering blood glucose test strips. The district court entered summary judgment of non-infringement on two of the patents (‘164 and ‘745 patents), and summary judgment of invalidity for anticipation on most claims of the ‘745 patent. After trial, the court found certain claims of the third patent (the ‘551 patent) invalid due to obviousness, and the whole patent unenforceable for inequitable conduct. The Federal Circuit affirmed on all counts.

For obviousness and inequitable conduct, the claim limitation at issue concerned a glucose sensor with an electrode “without an intervening membrane.” The district court did not clearly err in holding that the prior art disclosed a sensor without a membrane. There was also a motivation “to combine this sensor in a disposable form.” Any commercial success of patentee’s product was due to features already present in the prior art and did not have the required nexus to the patent.

On inequitable conduct, “[t]his is one of those rare cases in which a finding of inequitable conduct is appropriate.” The patentee told the PTO in an affidavit that the prior art’s disclosure that a membrane was “optional[] but prefer[ed]” would be understood to mean a membrane was required. The patentee withheld statements made to the European Patent Office that the same language meant a “membrane is optional.” This “highly material” statement “contradicted representations [the patentee] made to the PTO.” The district court did not err in finding an intent to deceive because the statements to the PTO were “absolutely critical” in securing allowance, contradicted statements made to the EPO, there was no credible explanation for the withholding, and the explanations that were proffered were “so incredible that they suggested an intent to deceive.” A district court’s “credibility determinations are ‘virtually unreviewable.’” Moreover, “[c]ases involving affidavits or declarations are held to a higher standard” than simple attorney argument about the prior art.

On non-infringement of the ‘164 and ‘745 patents, there was no error in finding that the accused product did not hold the blood sample in a “in a non-flowing manner” as required by the claims. On anticipation, the prior art disclosed the limitation at issue, and any “teaching away” is “inapplicable to an anticipation analysis.”

The dissent concurred with the result of all parts of the opinion except those with respect to inequitable conduct, arguing that the patentee’s EPO submissions did not contradict its affidavit to the PTO.

A copy of the opinion can be found here.