The Board appears to have been inconsistent in its conclusions about who bears the burden of proving the effective filing date of a patent claim. Earlier this year, the Board held that it did not need to determine if a petitioner was correct in its argument that claims at issue were not entitled to an earlier priority date “because entitlement to a priority date for any claim is a matter for which [Patent Owner] bears the burden of proof.” Liberty Mutual Ins. Co. v. Progressive Cas. Ins. Co., CBM2013-00009, Paper 10 (Mar. 28, 2013). The Board explained that since the patent owner only made a “conclusory statement” regarding the effective filing date of a claim, the claim would be treated as having the filing date of the patent at issue, and not an earlier filing date for the purposes of the institution decision. Id.

Last week, however, the Board denied certain grounds in a petition for IPR because the petitioner only provided conclusory statements regarding the effective filing date of a claim. See Hewlett-Packard Co. v. MCM Portfolio, LLC,IPR2013-00217, Paper 10 (Sept. 10, 2013). The Board noted that the petitioner “provides little explanation regarding its proposed effective filing date, basing its entire argument” on an alleged admission by the patent owner’s exclusive licensee made during an ITC investigation. The petitioner “does not explain why the actions of [patent owner’s] licensee in another proceeding would be applicable here; not does [petitioner] provide any evidence, aside from one conclusory statement by an expert…to support this assertion.” The Board noted that none of the priority applications were in the record in the proceeding, and the expert does not even mention the earlier filed applications cited in a certificate of correction, suggesting that he may not even have been aware of them. Therefore, the Board declined to institute inter partes review based on the intervening references.

Thus, it appears to be an open issue as to who bears the burden of showing that a patent claim is entitled to an earlier effective filing date in the petition. At this point, however, would-be petitioners should err on the side of caution and provide substantive evidence and analysis of the priority date until this apparent split in authority has been resolved.