Dubbing the defense of “inequitable conduct” (which renders an entire patent unenforceable) a “plague” on the patent system, the Federal Circuit, in its 2011 en banc opinion in Therasense Inc. v. Becton, tightened the legal standards for proving the defense to require clear and convincing evidence that:
- An individual associated with the prosecution of a patent application made an affirmative misrepresentation of a material fact, failed to disclose material information or submitted false material information to the patent office
- The individual did so with a specific intent to deceive the patent examiner into granting the patent.
The court held that the materiality of the information must be “but for” —i.e., had the information been disclosed, the patent would not have been allowed. After Therasense, some in the patent community proclaimed that the demise of the defense was inevitable.