The U.S. Supreme Court has granted Microsoft’s petition for a writ of certiorari seeking review of the stand of proof required to prove a patent invalid. Under current U.S. law, invalidity of a patent must be proven by “clear and convincing” evidence. The clear and convincing standard is a higher standard than the most commonly used standard in civil cases: “preponderance of the evidence,” which is often discussed as “more likely than not” or considered to require proof just beyond 50%. Patent infringement, as opposed to invalidity, is determined by the “preponderance of the evidence” standard. The “beyond a reasonable doubt” standard, used in criminal cases, is a higher standard than “clear and convincing” evidence, and “clear and convincing” is generally considered to be somewhere between “preponderance of the evidence” and “beyond a reasonable doubt.”
In Microsoft v. i4i Ltd., Microsoft seeks review of whether the “clear and convincing” standard should be used to determine patent validity, particularly in situations where the prior art used to prove invalidity was not considered by the U.S.P.T.O. in allowing the patent to issue. The Supremes have granted Microsoft’s request to review this issue. This is not the first time that Microsoft briefed this issue for the Supreme Court. In 2008, Microsoft filed a similar petition with the Supreme Court in Microsoft v. z4, seeking review of the “clear and convincing” proof requirement for invalidity, but withdrew the petition upon settlement. In the interest of full disclosure, I represented Microsoft in the early days of the z4 litigation in Texas. In his blog Patently-O, Dennis Crouch offers a great summary of the history of the i4i dispute and review of the “clear and convincing” standard.