Federal Circuit Clarifies Important IPR Estoppel Issues, PTAB LItigation Blog
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Under 35 U.S.C. § 315(e)(2), a patent challenger in an inter partes review (IPR) that reaches a final written decision is estopped from arguing in a district court or the ITC that the challenged patent is invalid based on grounds that were “raised or reasonably could have been raised” in the IPR. In Ironburg Inventions Ltd. v. Valve Corp., the Federal Circuit clarified two aspects of IPR estoppel, holding that (1) an IPR petition reasonably could have raised any grounds that “a skilled searcher conducting a diligent search reasonably could have been expected to discover,” and (2) the patent owner bears the burden of proving that petitioner estoppel should apply. Nos. 21-2296, -2297, and 22-1070 (Fed. Cir. Apr. 3, 2023). District courts had reached different conclusions on these issues, and so the Ironburg decision provides helpful clarity.
