On May 25th, the Federal Circuit, sitting en banc, issued a decision reversing and remanded the district court’s holding that the patent-in-suit was invalid due to inequitable conduct. (A copy of the decision can be found at the end of this post.) The patent remained invalid as anticipated, but the bar has been substantially raised for accused infringers attempting to prove the inequitable conduct defense – the “atomic bomb” of patent law, as Chief Judge Rader described it. With respect to the element of intent, the accused infringer must prove by clear and convincing evidence that the patentee acted with specific intent to deceive the PTO. “The accused infringer must prove…that the applicant knew of the reference, knew that it was material, and made a deliberate decision to withhold it.” Intent can still be established by circumstantial evidence, but a high level of materiality cannot satisfy the burden to prove intent. Also, the evidence “must be sufficient to require a finding of deceitful intent in the light of all the circumstances….The absence of a good faith explanation for withholding a material reference does not, by itself, prove intent to deceive.”




