Duty of Disclosure: Applicant’s Contradictory Statements to EPO and USPTO Support Finding of Inequitable Conduct

The Federal Circuit’s recent decision in Therasense, Inc. v. Becton, Dickinson & Co., No. 2008-1511 (Fed. Cir. Jan. 25, 2010) held that applicant’s statements made in proceedings before foreign patent offices may be required disclosures in prosecution before the USPTO (“PTO”), particularly when those statements directly contradict other statements made during prosecution. From the court’s holding: “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.”

The Therasense case involved U.S. Pat. No. 5,820,551, for a strip electrode used to measure the level of glucose in blood. The ‘551 patent is related to an earlier U.S. patent and its European counterpart. The statement “Optionally, but preferably when being used on live blood, a protective membrane surrounds both the enzyme and the mediator layers, permeable to water and glucose molecules” appeared in the specifications of all three patents.

In 1993, the European patent was revoked in an opposition proceeding based on a German reference. In a successful appeal to withdraw the revocation, the patentee distinguished the patented invention’s “optionally, but preferably” membrane requirement from the German reference, which required a membrane.

A few years later, during prosecution of the ‘551 patent, the prosecuting attorney, who was familiar with the EPO opposition proceedings, established a new point of novelty before the USPTO to advance the prosecution of the ‘551 patent. That new point of novelty was that never before was the sensor known to work without a membrane. This assertion directly contradicted an earlier statement made by the applicant during the EPO opposition proceedings.

The Federal Circuit affirmed the district court’s finding of invalidity of U.S. Pat. No. 5,820,551 due to inequitable conduct by applying the standard recently summarized by the Federal Circuit in McKesson Info. Solutions, Inc. v. Bridge Med., Inc.

To establish inequitable conduct by failure to disclose, the asserting party must show materiality of the information and the intent to deceive. The trial court held that the prosecuting attorney knew that to disclose the EPO opposition arguments would defeat the patent grant before the USPTO. The trial court then balanced the levels of materiality and intent, and found the withheld information “richly material” and that the prosecuting attorney had no explanation for his conduct, and that this was proved by clear and convincing evidence.

As we previously posted, a patent applicant’s duty of disclosure may also extend to references and office actions in “similar” but unrelated, co-pending patent applications. The Therasense and McKesson cases show continued development in the caselaw of inequitable conduct. Stay tuned for future developments.

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