Supreme Court Upholds Clear And Convincing Evidence Standard For All Fact Determinations In Patent Validity Challenges

June 9, 2011


A unanimous United States Supreme Court today confirmed the heightened "clear and convincing evidence" standard of proof for questions of fact regarding the validity of a patent. (Microsoft Corp. v. i4i Limited Partnership et al., Supreme Court No. 10-290, June 9, 2011 (i4i)).

The decision purports to reaffirm more than a century of settled law that had been called into question by the Supreme Court's 2007 statement that the rationale underlying the need for the clear and convincing evidence standard "seems much diminished" when a validity challenge is based on evidence that had not been presented to the PTO during a patent's examination. KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 426. The Court clarified in i4i that the clear and convincing evidence standard applies regardless of whether evidence of invalidity has been previously considered by the PTO. The i4i Court also suggested that juries should be instructed that the presentation of evidence not before the PTO makes the burden of demonstrating invalidity by clear and convincing evidence "easier to sustain."

The majority opinion, joined by seven Justices, focuses on Congress's intent in passing the Patent Act of 1952, including 35 U.S.C. § 282, which then stated: "A patent shall be presumed valid. The burden of establishing invalidity of a patent shall rest on a party asserting it.” (Section 282 has since been amended in ways not relevant to the issue before the Court in i4i.) The i4i Court held that, although the phrase "clear and convincing evidence" does not appear in § 282, Congress intended to codify the Court's unanimous 1934 decision in Radio Corp. of America v. Radio Engineering Laboratories, Inc., 293 U. S. 1, in which Justice Cardozo wrote "there is a presumption of validity, a presumption not to be overthrown except by clear and cogent evidence," id. at 2, and "a patent … is presumed to be valid until the presumption has been overcome by convincing evidence of error.” Id. at 7. Justice Cardozo's opinion was based on decisions dating as far back as the middle of the nineteenth century, including a Supreme Court decision from 1874 that applied a heightened evidentiary standard in a patent validity dispute. The Court also emphasized the importance of maintaining consistency with thirty years of Federal Circuit decisions that interpret § 282 to require a clear and convincing evidence standard.

The Court acknowledged the ongoing debate over the proper standard of review, concluding "[w]e find ourselves in no position to judge the comparative force of these policy arguments" and "[a]ny re-calibration of the standard of proof remains in [Congress's] hands." But the Court took a strong position against any "fluctuating standard of proof," in which different standards might apply depending on whether the evidence at issue had been considered by the PTO. The Court pointed out that one of the "impracticalities of such an approach arises from the fact that whether a PTO examiner considered a particular reference will often be a question without a clear answer," and it cited reexamination as an alternative for alleged infringers who seek to challenge a patent without having to satisfy the clear and convincing evidence standard. For more on the impracticalities of a fluctuating standard of proof, see Brett J. Williamson and Bo K. Moon, Maintaining The Standard Of Proof On Invalidity.

In a concurring opinion, Justice Breyer (joined by Justices Scalia and Alito) emphasized that the clear and convincing evidence standard applies only to fact determinations, and not to legal questions. Justice Thomas concurred only in the judgment. Chief Justice Roberts took no part in the consideration or decision of the case.

The i4i decision removes uncertainty potentially created by KSR regarding the proper standard of proof. As instructed by i4i, attorneys may argue that "new evidence supporting an invalidity defense may 'carry more weight' in an infringement action than evidence previously considered by the PTO," and that a jury should be "instructed to consider that it has heard evidence that the PTO had no opportunity to evaluate before granting the patent." But evidence of invalidity must ultimately satisfy the clear and convincing evidence standard to render a patent invalid.