On June 9, 2011, the Supreme Court in an 8-0 decision authored by Justice Sotomayor, affirmed the long-standing rule that a challenger must demonstrate invalidity of a patent by “clear and convincing evidence.” Microsoft Corp. v. i4i Ltd. Partnership, 564 U.S.__, slip op. at 20 (June 9, 2011).  Microsoft had argued for a more relaxed “preponderance of the evidence” standard in a case where the prior art that formed the basis for the challenge had not been considered by the Patent Office.  While the holding puts to rest speculation over whether the Court would apply the lesser standard of proof, the Court endorsed the use of a jury instruction on the weight to be given prior art evidence that had not been considered by the Patent Office, stating that such an instruction, “when requested, most often should be given.”  Id.at 17. 

Section 282 of the Patent Act of 1952 provides that “[a] patent shall be presumed valid” and “[t]he burden of establishing invalidity of a patent or any claim thereof shall rest on the party asserting such invalidity.”  35 U.S.C. § 282. While § 282 expressly places the burden of proof regarding validity of the patent upon an accused infringer, it does not expressly address the standard of proof.  Microsoft argued that the preponderance standard applied generally or, in the alternative, at least where the prior art asserted had not been considered by the Patent Office.  The Court rejected both contentions.  

The Supreme Court rejected Microsoft’s first contention by finding that Congress had adopted the heightened standard from the common-law in 1952 when it enacted § 282.  The Court determined that by the time of the 1952 Act, the common law presumption of validity reflected the “universal understanding” that the preponderance standard was insufficient.  That understanding was reflected in the holding of Radio Corp. of America v. Radio Engineering Laboratories, Inc., 293 U.S. 1 (1934). In that case, the Supreme Court held that an accused infringer must overcome the presumption of validity by "clear and cogent evidence." Id.at 2.  Accordingly, the Court held that the codification of the presumption in § 282 brought with it its common-law meaning, including the heightened standard proof, and there was no reason to “drop” the heightened standard simply because §282 does not explicitly recite it.

In arguing for the lesser “preponderance of the evidence” standard of proof when the prior art was not considered by the Patent Office, Microsoft relied in part on the Supreme Court’s dicta in KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 426 (2007), that at least in cases where the invalidating prior art was not before the Patent Office, the presumption of validity “seems much diminished.”    

Notwithstanding its earlier observation, the Supreme Court rejected the notion of a variable standard of proof.  The Court acknowledged language found in “numerous courts of appeals” cases before the 1952 Act, that referred to the presumption of validity being “weakened” or “dissipated” when the evidence was not considered by the Patent Office.  However, it explained that such language could not be read as supporting a different standard.  “Instead, we understand these cases to reflect the same common sense principle that the Federal Circuit has recognized throughout its existence—namely, that new evidence supporting an invalidity defense may ‘carry more weight’ in an infringement action than evidence previously considered by the Patent Office.”   Slip op. at 17.  Accordingly, "new evidence" of invalidity may make it “easier” for a challenger to meet the “clear and convincing” standard.

The Court suggested that the weight to be given this new evidence be explained in an instruction to the jury:

[A] jury instruction on the effect of new evidence can, and when requested, most often should be given. When warranted, the jury may be instructed to consider that it has heard evidence that the PTO had no opportunity to evaluate before granting the patent. . .  [T]he jury may be instructed to evaluate whether the evidence before it is materially new, and if so, to consider that fact when determining whether an invalidity defense has been proved by clear and convincing evidence.

Id.at 17.  This language will undoubtedly increase the frequency of requests for a specific instruction on the weight of the new evidence and on the use of such instructions. 

Justice Breyer, joined by Justices Scalia and Alito, wrote a concurring opinion which emphasizes the need to pay careful attention to the distinction between fact questions and legal questions, noting that the standard only applies to evidence of the facts.  The Court’s opinion, slip op. at 2, does note that the ultimate question of patent validity is a question of law and that the same factual questions underlying the Patent Office’s original examination will also be present in an infringement action.  Id.  While this language is suggestive, the Court’s opinion never expressly states that the standard of proof applies only to the factual questions.  The concurrence thus raises the question of whether a court should refrain from applying the clear and convincing standard to legal conclusions, such as whether given facts render an invention obvious.  Further, the observations of the concurrence may impact the specific questions put to the jury in the form of a special verdict and instructions regarding the standard of proof.  

Thus, the development of the patent law may be more affected by dicta from Microsoft Corp. v. i4i Ltd. Partnership than by its holding, which affirms the long-standing “clear and convincing” standard.