In a recent decision, the Federal Circuit confirmed that the burden of proof shifts from petitioner to patent owner to establish patentability of substitute claims proposed in AIA post-grant proceedings. The case, Nike, Inc. v. Adidas AG, No. 2014-1719 (Feb. 11, 2016), involved an appeal of a PTAB decision denying Nike’s motion to amend claims in an IPR. In reviewing the burden of proof for claim amendments, the Federal Circuit agreed that the burden is on the patent owner to demonstrate that the substitute claims are patentable not only over the prior art already of record but also over prior art known to the patent owner. Moreover, the Federal Circuit ruled that the patent owner may satisfy its burden as to prior art not of record by meeting its duty of candor and good faith in addressing additional prior art known to the patent owner, if any.