Holding that the prosecuting attorneys had violated their duty of disclosure by failing to disclose to the U.S. Patent and Trademark Office (USPTO) contradictory statements made to the European Patent Office (EPO) regarding the European counterpart of another patent family, the U.S. Court of Appeals for the Federal Circuit affirmed a district court’s finding of inequitable conduct in parallel cases. Therasense, Inc. v. Becton, Dickinson & Co., Case No. 08-1511 (Fed. Cir., Jan. 25, 2010) (Dyk, J.; Linn, J., concurring-in-part and dissenting-in-part); Therasense, Inc. v. Becton, Dickinson & Co., Case No. 09-1008 (Fed. Cir., Jan. 25, 2010) (Linn, J.).

Over the last few years, the Federal Circuit has toughened the standard for proving inequitable conduct. In Star Scientific, the Federal Circuit explained that the clear and convincing standard is not met, as a matter of law, unless the inference of intent to deceive is the single most reasonable inference. Here, in the first case (Case No. 08-1511), the Federal Circuit held that this is a “rare” situation in which a finding of inequitable conduct is appropriate and found that the district court was “clearly correct.”

The technology-in-suit is for disposable test strips used by diabetic patients. The test strips contain an electrode and reactant system that measures blood sugar. Measurements can be made either from whole blood samples or from other types of samples. The electrode system may have a membrane on top of it.

The inequitable conduct issue turned on the failure to disclose to the USPTO that inconsistent representations had been made by the patent owner in another forum, the EPO, about another patent with a U.S. counterpart that was now prior art in the litigation. In the EPO, the patent owner argued that “optionally, but preferably” meant that a membrane was not required for whole blood testing. In the USPTO, the patent owner argued that the same language would be read by a person of ordinary skill to mean that a membrane was required. The Federal Circuit found these two positions flatly inconsistent. Judge Linn dissented and suggested a reading of the language in context that harmonized the positions taken in the EPO and PTO and thus would support a conclusion of no intent to deceive the USPTO. The Court distinguished precedent involving mere attorney argument to the USPTO about prior art, in which no inequitable conduct was found. None of those cases involved inconsistent statements made in another forum and not disclosed to the USPTO. The Court also emphasized that this case involved a sworn affidavit submitted to the USPTO, which triggers a higher standard.