In Exergen Corp. v. Wal-Mart Stores Inc., 575 F.3d 1312, 1328 (Fed. Cir. 2009), the U.S. Court of Appeals for the Federal Circuit gave teeth to the pleading requirements for inequitable-conduct claims in patent infringement litigation, holding that “the pleading must identify the specific who, what, when, where and how of the material misrepresentation or omission committed before the” U.S. Patent and Trademark Office (PTO). Accused infringers must plead specific facts supporting an inequitable-conduct claim and may need to await discovery before asserting those claims.
Parties accused of infringement long have argued that the asserted patent is unenforceable for inequitable conduct — such as by alleging that the applicants failed to disclose or misrepresented key prior art to deceive the PTO into granting the patent. This equitable defense is governed by a balancing test in which the court weighs the materiality of the prior art and evidence of the applicant’s intent to deceive the PTO to determine whether there was inequitable conduct. See PerSeptive Biosystems Inc. v. Pharmacia Biotech Inc., 225 F.3d 1315, 1318-19 (Fed. Cir. 2000).
