Microsoft Challenges Invalidity “Clear and Convincing” Standard

In an en banc petition to the United States Court of Appeals for the Federal Circuit, Microsoft challenges the “clear and convincing” standard of proof required to render a patent invalid.

It is black letter law in the field of patents that once a patent is issued, it is presumed to be valid and “clear and convincing” evidence is required to overturn the presumption of validity to prove a patent invalid.  In its petition in the Lucent v. Gateway litigation originating in the United States District Court for the Southern District of California, Microsoft argues that the standard of proof for an invalidity defense should be “preponderance of the evidence” for prior art defenses where the prior art had not been before the U.S.P.T.O. examiner during prosecution of the patent-in-suit.