Patent Litigation: Federal Circuit Tightens Standards for Inequitable Conduct

Sullivan & Cromwell LLP - May 31, 2011

On May 25, 2011, the United States Court of Appeals for the Federal Circuit issued its long-awaited en banc opinion in Therasense, Inc. v. Becton, Dickinson & Co. addressing the inequitable conduct doctrine. Inequitable conduct is an equitable defense to patent infringement that can render a patent unenforceable upon a showing that a patent holder withheld or misrepresented material information during prosecution of a patent with intent to deceive the U.S. Patent and Trademark Office. The Therasense opinion expressly “tightens” the doctrine, affirming that it can only succeed upon a showing of both (1) specific intent to deceive the PTO and (2) either “but-for” materiality or “affirmative acts of egregious misconduct.”