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In Ingenico Inc. v. IOENGINE, LLC, No. 23-1367 (Fed. Cir. May 7, 2025), a Courts of Appeals for the Federal Circuit panel unanimously interpreted the inter partes review (IPR) statute in a way that weakens the IPR estoppel provision.

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Patent challengers generally like Inter Partes Reviews (IPRs) for their speed, efficiency, and access to the PTAB’s significant technical and legal expertise. One risk to filing an IPR request is that, if it results in final written decision, the IPR triggers an estoppel provision that prevents challengers from asserting in district court (or the ITC) “any ground that the [IPR] petitioner raised or reasonably could have raised during that inter partes review.” 35 U.S.C. § 315(e)(2) (emphasis added).

As many readers of this alert will know, IPR petitioners can challenge a patent under 35 U.S.C. §102 or §103 on the basis of patents or printed publications. See 35 U.S.C. § 311(b). In the context of IPR estoppel, some courts have interpreted the meaning of “ground” to include not only patents and printed publications but also any non-publication prior art (e.g., products that were “on sale,” “public use,” or “otherwise available to the public”) that is materially identical to patents or printed publications the petitioner raised or reasonably could have raised in the prior IPR. See, e.g., Wasica Fin. GmbH v. Schrader Int'l, Inc., 432 F. Supp. 3d 448, 454–55 (D. Del. 2020) (holding that IPR estoppel applies to such device art); Boston Sci. Corp. v. Cook Grp. Inc., 653 F. Supp. 3d 541, 593–94 (S.D. Ind. 2023).

But the Ingenico court interpreted the word “ground” more narrowly to mean “theories of invalidity” available to an IPR challenger, rather than as referring more broadly to the prior art or technology used in the prior IPR. “[A] ground is not the prior art asserted during an IPR. In drafting 35 U.S.C. § 315(e)(2), Congress could have precluded petitioners from asserting in district court that the claim is invalid on any prior art that the petitioner raised or reasonably could have raised during that inter partes review, but Congress chose not to. Instead, Congress precluded petitioners from asserting grounds in district court.” Ingenico at 14 (emphasis in original).

The upshot is that, under the Ingenico court’s ruling, IPR estoppel does not prevent challengers from raising non-publication prior art in subsequent district court or ITC proceedings, even if the technology embodied in the non-publication prior art is materially identical to the technology disclosed in publications the challenger raised or reasonably could have raised in a prior IPR. The result is that the IPR estoppel provision loses its bite.

Note that this case does not affect the estoppel scope of Post Grant Reviews (PGRs), because a PGR challenger may rely on the full gamut of § 102 prior art.

Technical drawings of mechanical parts shown as detailed line diagrams on a white background.

Technical mechanical drawings featuring detailed line diagrams and measurements.

Federal Circuit Resolves Conflict Over Scope of IPR Estoppel

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