In ParkerVision, Inc. v. Qualcomm Inc., No. 2022-1755, -2221 (Fed. Cir. Sept. 6, 2024) (“ParkerVision III”), the Federal Circuit held that, due to the difference in burdens of proof in PTAB IPR proceedings and in district court cases, collateral estoppel cannot be applied in a district court case based on findings made


A judgment in an interference disposes of all issues that were, or by motion could have properly been, raised and decided. A losing party who could have properly moved for relief on an issue, but did not so move, may not take action in the Patent Office after the judgment that is inconsistent with that party’s failure to move. 37 C.F.R. § 41.127. This is known as “interference estoppel,” and was recently applied by the PTAB in partially denying an IPR petition. See