When claims survive an inter partes review, a petitioner has only limited options to challenge the surviving claims either at the patent office or in district court.
Party asserting IPR estoppel bears the burden of proof because it is the party asserting and seeking benefit from the affirmative defense of IPR estoppel. Reasoning consistent with general principle that party asserting an affirmative defense bears the burden to prove it.
This case addresses the “skilled and diligent searcher” standard used for establishing Inter Partes Review (“IPR”) estoppel (or lack thereof). In particular, this case establishes: (1).
Who Bears the Burden of Proof for IPR Estoppel? In Ironburg Inventions Ltd. v. Valve Corp., Appeal No. 21-2296, the Federal Circuit held that the patentee has the burden .
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.