On June 9, 2011, the Supreme Court rejected Microsoft’s contention that a preponderance of the evidence should be sufficient to establish patent invalidity in an 8-0 (Roberts abstained) opinion, which affirmed the Fed. Cir.’s opinion (for a change). (The decision can be found at the end of this post.) The Court interpreted Congress’ intent in 35 USC 282 to preserve the presumption of validity of a patent claim unless an attacker can meet the burden of presenting “clear and convincing” evidence of invalidity.
The Court also rejected the notion that some sort of “fluctuating standard of proof” should apply in situations in which the evidence relied upon was not considered by the PTO during prosecution. Even if the primary rationale behind the clear and convincing standard, that the PTO applied its expertise correctly, “seems much diminished’ (citing KSR 550 US 398), the Court held that Congress “codified the common-law presumption of patent validity and, implicitly the heightened standard of proof attached to it” and that standard of proof must still be met. The Court suggested that, in such cases, the jury could be instructed that it could give weight to the fact that the evidence before it is “materially new” when determining if clear and convincing evidence of invalidity had been presented.