Petitioners in post-grant review (PGR) and covered business method (CBM) proceedings have a greater arsenal of prior art to develop patentability challenges than in inter partes review (IPR) proceedings. While IPR challenges are limited to patents and printed publications, prior art challenges presented in PGRs and CBMs can rely on prior public use. 35 U.S.C. §§ 321(b) and 282(b)(2); AIA § 18(a)(1)(C); 37 C.F.R. §§ 42.204(b)(2) and 42.304(b)(2). As is evident from the decisions discussed below, the Patent Trial and Appeal Board (PTAB) has wrestled with assessing the sufficiency of evidence presented to support public use assertions in the context of institution decisions.

Testimony Consistent with Cited References and Unchallenged by Patent Owner

In Arkema Inc. v. Honeywell Int’l Inc., PGR2016-00012, Paper 13 (PTAB Sep. 2, 2016), the petitioner challenged a patent directed to a refrigerant composition used in automobile air conditioning systems. The petitioner based one of its challenges on a prior public use, asserting that the claimed refrigerant composition had previously been used in air conditioning systems of automobiles used by the public. Id. at 4. In support of its assertion, the petitioner submitted a declaration of an expert witness who testified that the air conditioning systems and claimed refrigerants were in public use before the effective filing date. Id. at 29.

The PTAB panel determined that the witness testimony was sufficient for purposes of instituting trial. The panel indicated that the testimony “is consistent with references of record” and supported petitioner’s claim charts that demonstrate “how the four car models in public use anticipate the claimed subject matter.” Id. The panel also noted that “Patent Owner chose not to address the merits of the Petition” on this issue. Id. Thus, the panel gave credit to the witness testimony and instituted trial based on the asserted public use.

Uncorroborated Testimony of an Interested Witness

The PTAB came to a different conclusion in Netsirv v. Boxbee, Inc., PGR2015-00009, Paper 10 (PTAB Aug. 4, 2015). In Netsirv, the petitioners asserted that the claimed methods were anticipated by a prior use. Id. at 12. In support of this assertion, the president and CEO of one of the petitioners testified that he “has been performing the claimed method steps using the Netsirv software system in conjunction with the operation of his storage business.” Id. The panel determined that such testimony was insufficient for establishing public use for purposes of instituting trial. The fact that the testimony was uncorroborated weighed heavily in the panel’s decision:

[I]t has become settled law that the testimony of witnesses alleging prior public use, or any other theory of invalidity under 35 U.S.C. § 102, must be corroborated to prove the credibility of the testimony by clear and convincing evidence.

Id. at 13. While the panel was careful to point out that it is “unaware of any binding precedent that requires that the testimony of witnesses alleging prior public use must be corroborated to show unpatentability in post-grant reviews” (Id. at 14), the panel ultimately faulted the petitioners for not providing such corroborative evidence. Specifically, the panel noted that the petitioners’ witness was an interested party, and that the witness “does not offer corroboration for his testimony, and no explanation was given for why corroborative evidence was not provided.” Id. at 17. Thus, the panel concluded that the witness’s “testimony alone is insufficient to establish prior public use.” Id.


As is apparent from the above decisions, the PTAB’s assessment of the sufficiency of public use evidence is a highly fact-dependent inquiry. At first glance, the outcome in Arkema may appear to be at odds with the Netsirv decision. In both cases, the petitioners relied on the uncorroborated testimony of a single witness to demonstrate public use. However, in Arkema, the panel gave weight to the petitioner’s documentary evidence that supported the witness’s testimony. Further, in Netsirv, the fact that the testimony was of an interested witness was an important factor. When possible, petitioners may wish to consider providing corroborative evidence of witness testimony of prior public use, particularly in situations where such testimony is unsupported by documentary evidence or submitted by an interested witness.