The Supreme Court recently agreed to decide whether the Federal Circuit correctly reads the Patent Act’s presumption of validity to require a defendant always to prove patent invalidity by clear and convincing evidence. At the petition stage in the Supreme Court, the eleven amicus briefs took several different positions as to what the standard of proof should be. This client alert summarizes the views taken to date in Microsoft Corp. v. i4i Limited Partnership, No. 10-290. The merits-stage briefing will no doubt have even more amici and possibly additional positions on the standard.

Microsoft’s petition for certiorari described the Federal Circuit as holding “that Microsoft was required to prove its defense of invalidity under 35 U.S.C. § l02(b) by ‘clear and convincing evidence,’ even though the prior art on which the invalidity defense rests was not considered by the Patent and Trademark Office before issuance of the asserted patent.” The question presented is: “Whether the court of appeals erred in holding that Microsoft’s invalidity defense must be proved by clear and convincing evidence.”