Microsoft Corp. v. I4i Limited Partnership

Summary

The Supreme Court held that 35 U.S.C. §282 requires an invalidity defense to be proved by clear and convincing evidence, affirming the Federal Circuit’s interpretation. The Court reasoned that Congress incorporated the common‑law presumption of validity, which historically carried a heightened evidentiary standard. Two concurring opinions agreed with the result but differed on whether the statutory language itself codified the standard.