Yesterday, in Therasense, Inc. v. Becton, Dickinson and Company (Fed. Cir. 2011) (en banc) (a copy is attached at the end of this post), the Federal Circuit handed down an historic and much needed update to the law of inequitable conduct. The en banc (6-1-4) decision markedly increased the requirement for proof of inequitable conduct: “This court now tightens the standards for finding both intent and materiality in order to redirect a doctrine that has been overused to the detriment of the public.” The court rejected the “sliding scale” approach that previously allowed intent to deceive to be inferred from strong materiality. The new standard makes intent and materiality separate requirements, and forbids a court from inferring intent solely from a strong showing of materiality. Now, evidence of deceitful intent must be weighed separately from materiality, and proven by clear and convincing evidence. The clear and convincing standard requires that a finding of deceptive intent must be “single most reasonable inference able to be drawn from the evidence.”
In addition, the court raised the standards for proof of materiality, holding that “as a general matter, the materiality required to establish inequitable conduct is but-for materiality.” But-for materiality requires that the PTO would not have allowed a claim had it been aware of the undisclosed prior art.
The following passages from majority opinion in Therasense set forth the heart of the decision: