By Rachel Emsley, Nathan North and Mark Feldstein (February 15, 2018, 11:47 AM EST) -- Validity challenges in inter partes review and post-grant review at the Patent Trial and Appeal Board often rely on nonpatent literature publications that petitioners must show to be "prior art."[1] This presents a twofold challenge for petitioners: First, they must provide evidence that the nonpatent literature was "publicly accessible,"[2] and second, they must ensure that the nonpatent literature and supporting evidence complies with the Federal Rules of Evidence, including hearsay and authentication rules.[3] The nonpatent literature topic has become a hot one leading the PTAB to dedicate its "boardside chat" session on Dec. 7, 2017, to discussing public accessibility decisions and the types of evidence petitioners may present.[4] But, the second issue, whether the evidence comports with the FRE, may be less familiar to parties at the PTAB. Unlike in original examination and ex parte re-examination where the FRE do not apply, the U.S. Patent and Trademark Office expressly adopted the FRE for AIA trials.[5] Bright-line guidance has yet to emerge from the PTAB on applying the FRE to nonpatent literature, or how it may differ from district courts in this area. This article reviews exemplary cases applying the FRE's hearsay rules in both venues to highlight the various precedent litigants should consider....