Federal Circuit Limits IPR Estoppel to “Grounds,” not Prior Art Evidence Underpinning the “Grounds”

In Ingenico Inc. v. IOENGINE, LLC, No. 2023-1367 (Fed. Cir. May 7, 2025), the Federal Circuit clarified the scope of IPR estoppel under 35 U.S.C. § 315(e)(2) and distinguished “grounds” from the prior art evidence supporting those grounds. The Federal Circuit held that IPR estoppel applies only to invalidity grounds that the claimed invention was patented or described in a printed publication. The Court clarified that IPR estoppel does not preclude grounds based on other invalidity theories, including that a claimed invention was known or used by others, on sale, or in public use, even if printed publications supporting those grounds were raised or could have been raised in an IPR.

IOENGINE (the patent owner) sued Ingenico for infringement. Ingenico filed an IPR and obtained a favorable decision that found most of the asserted claims invalid. At trial before the district court, Ingenico introduced a prior art system as evidence of invalidity for the remaining claims as being “on sale,” “in public use,” or “known or used by others” before the critical date. The jury found certain asserted claims infringed but invalid over the prior art system.

On appeal to the Federal Circuit, IOENGINE argued that IPR estoppel should have precluded Ingenico from presenting the prior art system at trial. According to IOENGINE, the system was cumulative of corresponding documentation relating to the system, which could have been raised in the IPR because they were printed publications, and that the system should have been excluded as raising the same “ground.”

The Federal Circuit disagreed. The Court interpreted “ground” as used in the IPR statute and resolved a long-standing split among district courts regarding the scope of IPR estoppel. Section 315(e)(2) precludes a patent challenger from asserting “any ground that [a] petitioner raised or reasonably could have raised” during an IPR. According to the Federal Circuit, “ground(s)” are invalidity theories available under §§ 102 and 103, not the corresponding evidence. The Court stated that Congress intentionally limited grounds in an IPR to challenges that the claimed invention was patented or described in a printed publication and excluded other grounds. The Court found that under the statutory design, a petitioner could not raise a ground in an IPR challenging the claimed invention as “known or used by others, on sale, or in public use.”

The Court drew a distinction between a “ground” and the prior art evidence supporting a ground: While patents and printed publications are evidence supporting a ground, such evidence is not coextensive with a ground. IPR estoppel precludes a patent challenger from asserting certain “grounds” in district court. It does not, however, preclude a patent challenger from relying on the same patents and printed publications as evidence to support a ground that could not be raised during an IPR.

Turning to the case at hand, the Court concluded that Ingenico was not precluded from presenting the prior art system with related printed publication documentation to show that the claimed invention was known or used by others, on sale, or in public use. These were separate grounds that Ingenico could not have raised in the IPR.