Federal Circuit Clarifies Evidentiary Burdens
First, a clarification of terminology. We will refer to the generic problem of burdens only in the plural—burdens of proof—because there are within that phrase two distinct, and quite different, ideas. One is the burden of persuasion. That is the ultimate burden assigned to a party who must prove something to a specified degree of certainty—beyond a reasonable doubt (the criminal law standard of proof for guilt); by a preponderance of the evidence (the usual civil law standard for proof of a fact); or, perhaps, something in between, such as "clear and convincing," the patent law evidentiary standard for establishing that a patent, otherwise presumed valid, is invalid . . . . Failure to prove the matter as required by the applicable standard means that the party with the burden of persuasion loses on that point—thus, if the fact trier of the issue is left uncertain, the party with the burden loses. see 35 U.S.C. § 282; Am. Hoist & Derrick Co. v. Sowa & Sons, Inc.See generally Christopher B. Mueller & Laird C. Kirkpatrick, Evidence § 3.1 (1995); Charles Alan Wright & Kenneth W. Graham, Jr., Federal Practice & Procedure § 5122 (2d ed. 2005).
A quite different burden is that of going forward with evidence—sometimes referred to as the burden of production—a shifting burden the allocation of which depends on where in the process of trial the issue arises. See generally Christopher B. Mueller & Laird C. Kirkpatrick, Evidence §§ 3.1, 3.2 (1995); Charles Alan Wright & Kenneth W. Graham, Jr., Federal Practice & Procedure § 5122 (2d ed. 2005). We understand, and we shall use here, the phrase ‘going forward with evidence’ to mean both producing additional evidence and presenting persuasive argument based on new evidence or evidence already of record, as the case may require.
PowerOasis was issued between the time the briefing in this case was completed and the time oral argument in the case was held.
In affirming the trial court’s judgment, this court’s opinion noted that the trial court "held that PowerOasis had the burden of proving that it is entitled to claim priority to the filing date of the Original application." 522 F.3d at 1303. In our affirmance, however, we stated that once T-Mobile satisfied its initial burden of production by coming forward with evidence that the MobileStar Network was anticipatory prior art, "the burden was on PowerOasis to come forward with evidence to the contrary." Id. at 1305 (emphasis added). We then concluded that the "district court therefore correctly placed the burden on PowerOasis to come forward with evidence to prove entitlement to claim priority to an earlier filing date." Id. at 1305-06 (emphasis added).
Nevertheless, Gennum is not alone in reading PowerOasis to have modified the traditional burdens rule so that the patentee has the burden of persuasion to prove it was entitled to the earlier filing date. Carefully read, however, our decision in PowerOasis says nothing more than, and should be understood to say, that once a challenger (the alleged infringer) has introduced sufficient evidence to put at issue whether there is prior art alleged to anticipate the claims being asserted, prior art that is dated earlier than the apparent effective date of the asserted patent claim, the patentee has the burden of going forward with evidence and argument to the contrary. As we noted earlier, it is a long-standing rule of patent law that, because an issued patent is by statute presumed valid, a challenger has the burden of persuasion to show by clear and convincing evidence that the contrary is true. That ultimate burden never shifts, however much the burden of going forward may jump from one party to another as the issues in the case are raised and developed. Correctly understood, PowerOasis is fully consistent with this understanding; until such time as these rules are abrogated by statute, by this court sitting en banc, or by the Supreme Court, the opinion in PowerOasis could not be otherwise.