On May 7, 2025, the Federal Circuit issued a decision in Ingenico, Inc. v. IOENGINE, LLC, effectively holding that 35 U.S.C. § 315(e)(2) estoppel cannot preclude an IPR petitioner from advancing in a district court trial an invalidity argument that alleges the claimed subject matter was known or used by others, on sale, or in public use, such as in a prior system or device.
For context, Section 311(b) limits an inter partes review (IPR) petitioner to anticipation or obviousness challenges predicated on only "prior art consisting of patents or printed publications." Section 315(e)(2) states that, where the IPR results in a final written decision of a claim, the petitioner is estopped from asserting in district court that the "claim is invalid on any ground that the petitioner raised or reasonably could have raised during that inter partes review."
The court in Ingenico held that Section 315(e)(2) "applies only to" invalidity theories advanced in district court based on "prior art patents or printed publications," and does not preclude invalidity theories at the district court trial that the claimed subject matter was "known or used by others, on sale, or in public use."
Ingenico had filed IPR petitions challenging the asserted patents, which resulted in final written decisions. At trial, the district court permitted Ingenico to present an invalidity theory that the asserted claims were anticipated or obvious based on a prior sale, public use, and/or knowledge by another of a prior device. Ingenico prevailed on the invalidity argument pertaining to the prior device.
On appeal, IOENGINE argued that Ingenico should have been estopped under Section 315(e)(2) from presenting its invalidity theories because the prior device functionality was "entirely cumulative and substantively identical to" printed publications that could have reasonably been raised in Ingenico's IPRs. The Federal Circuit rejected the theory and acknowledged that it was settling a split among district courts on the meaning of a "ground" under Section 315(e)(2). Certain districts had interpreted "ground" as the underlying invalidity theory, while other districts had interpreted "ground" as the particular patents and printed publications forming the basis of invalidity.
The court held that "grounds [under Section 315(e)(2)] are the theories of invalidity available to challenge a claim under [Sections] 102 and 103," whereas the patents and printed publications relied upon in an IPR are "evidence that support a ground that a claimed invention was patented or described in a printed publication [but] are not coextensive with a ground." The court also found inapposite IOENGINE's argument that Ingenico reasonably could have presented the supporting printed publication evidence corresponding to the prior art device in an IPR, as even assuming this were true, Ingenico could only use these publications to assert that "the claimed invention was described in" those publications, but could not assert in the IPR that the prior device was known or used by others, on sale, or in public use.
Thus, there is now a clear line as to which types of invalidity theories are estopped under Section 315(e)(2): (i) "IPR estoppel applies only to a petitioner's assertions in district court that the claimed invention is invalid under 35 U.S.C. §§ 102 or 103 because it was patented or described in a printed publication," and (ii) "IPR estoppel does not preclude a petitioner from asserting that a claimed invention was known or used by others, on sale, or in public use in district court" as "[t]hese are different grounds that could not be raised during an IPR."