Stopping Holes in Your IPR Estoppel Arguments

On April 3, 2023, in Ironburg Inventions Ltd. v. Valve Corp., Nos. 21-2296, 21-2297, 22-1070 (Fed. Cir. Apr. 3, 2023), the Federal Circuit for the first time defined the standard for determining the scope of estoppel set forth in 35 U.S.C. § 315(e)(2) for prior art that was not raised in an inter partes review (“IPR”) petition. Under Section 315(e)(2), the petitioner for an IPR that reaches a final written decision may not assert invalidity in a district court or at the International Trade Commission based on “any ground that the petitioner raised or reasonably could have raised” in the IPR. The Federal Circuit held that grounds the petitioner “reasonably could have raised” are “invalidity grounds a skilled searcher conducting a diligent search reasonably could have been expected to discover.” Further, the court held that it is the patent owner who bears the burden of establishing in the district court that the estoppel applies. Read more