The U.S. Supreme Court recently granted certiorari to Microsoft in a case involving patent invalidity.  Microsoft is challenging a Federal Circuit Court of Appeals finding of validity in favor of patent holder, i4i, in a case that has been long fought in the lower courts, and resulted in an award of over $200 million in damages to i4i.  In its decision, the Federal Circuit relied on its long standing precedent that patent invalidity must be proven by “clear and convincing evidence.”

Microsoft argues that the Federal Circuit erred in requiring this heightened standard, and suggest that the lesser “preponderance of the evidence” standard should apply to determinations of patent invalidity, as is the case in finding patent infringement.  The “preponderance of the evidence” standard applies in most civil actions and essentially requires a finding that it is “more likely than not” that the evidence presented is true, whereas the higher “clear and convincing” standard requires a “substantially more likely than not” or “highly probable” finding.

A further issue which Microsoft has raised is the fact that the prior art on which its invalidity defense is based was not considered by the U.S. Patent and Trademark Office.  A decision is expected from the Supreme Court by June 2011.