Supreme Court reaffirms patent invalidity must be proved by clear and convincing evidence

The Supreme Court in Microsoft v. i4i affirmed that 35 U.S.C. § 282 of the Patent Act requires an invalidity defense to be proved by clear and convincing evidence. In so holding, the Supreme Court rejected Microsoft’s position that, when the U.S. Patent and Trademark Office has not considered the evidence of invalidity in prosecuting the patent, the appropriate standard should be a preponderance of evidence.

Microsoft was sued by i4i alleging that Microsoft’s 2003 and 2007 versions of Microsoft Word infringed i4i’s U.S. Patent No. 5,787,449 (‘449 Patent), which relates to custom XML. Microsoft counterclaimed and sought a declaration that the ‘449 Patent was invalid under § 102(b)’s on-sale bar, which precludes a patent from issuing for any invention that was on sale in this country more than one year prior to the filing of a patent application.