Defense of Inequitable Conduct Law and Legal Definition

Defense of inequitable conduct is a defense available in patent law. The defense of inequitable conduct applies when the patent applicant has made a material misstatement or omission with intent to deceive. In an action for patent infringement, this defense charges the plaintiff with breaching the duty of candor and good faith. Clear and convincing evidence is required and the defendant should show that the plaintiff intentionally withheld material information from or misled the examiner. The Supreme Court derived the inequitable conduct defense from the equitable doctrine of "unclean hands." The doctrine of unclean hands denies a party equitable relief when there is evidence of bad faith. Although judicially created, the defense possesses statutory precursors that date back to the origins of the patent system in the United States.