Federal Circuit Defines Scope of IPR Estoppel

Background

The scope of an IPR is limited to “a ground that could be raised under [35 U.S.C. § 102, related to anticipation, or 35 U.S.C. § 103, related to obviousness] and only on the basis of prior art consisting of patents or printed publications.”² Further, the IPR estoppel statute provides:

(2) Civil actions and other proceedings. The petitioner in an inter partes review of a claim in a patent under this chapter that results in a final written decision under section 318(a), or the real party in interest or privy of the petitioner, may not assert either in a civil action arising in whole or in part under section 1338 of title 28 or in a proceeding before the International Trade Commission under section 337 of the Tariff Act of 1930 that the claim is invalid on any ground that the petitioner raised or reasonably could have raised during that inter partes review.³

In 2018, IOENGINE, LLC (“IOENGINE”) sued PayPal Holdings, Inc. (“PayPal”) in the District of Delaware for patent infringement. Because it supplied PayPal’s accused products, Ingenico Inc. (“Ingenico”) filed a declaratory judgment action against IOENGINE. Prior to trial, Ingenico filed IPR petitions challenging IOENGINE’s asserted patents, which resulted in final written decisions that held most of the challenged claims unpatentable. At summary judgment, IOENGINE moved to preclude Ingenico, pursuant to the IPR estoppel statute, from relying on a prior art flash drive device sold in the early 2000s because IOENGINE believed it was entirely cumulative and substantively identical to printed publications relied on by IOENGINE as evidence of the device, and thus reasonably could have been raised as prior art printed publications in the IPRs.⁴

The district court ruled that “Ingenico will be estopped from relying on those documents [to prove invalidity] except to the extent . . . that they form part of a substantively different combination of references that could not reasonably have been raised in the IPRs.”⁵ The district court’s reasoning was consistent with how some district courts have analyzed the scope of IPR estoppel — interpreting the term “ground” in the IPR estoppel statute to refer to “the particular patents and printed publications on which invalidity arguments are based [in IPRs], and that the supporting affidavits, declarations, and the like are evidence, not ‘grounds.’” Other district courts, however, have interpreted the term “ground” to refer to “the underlying legal arguments, which incorporate patents, printed publications, and cumulative device art.”⁶

At trial, Ingenico introduced evidence of the prior art flash drive device, supported by evidence in the form of printed publications, arguing that the asserted claims were anticipated or obvious because the device was either “on sale” or “in public use” under 35 U.S.C. § 102(b) (pre-AIA), or “known or used by others . . . before the date of the invention” under 35 U.S.C. § 102(a) (pre-AIA)—not that it was “patented or described in a printed publication . . . before the invention” under 35 U.S.C. § 102(a) (pre-AIA). The jury returned a general verdict finding the asserted claims infringed, but invalid as anticipated and obvious. IOENGINE timely filed a motion for a new trial, arguing that IPR estoppel should have precluded Ingenico from relying on the prior art flash drive device, which the district court denied. IOENGINE timely appealed to the Federal Circuit.⁷

The Opinion

Recognizing the split among district courts, and its opportunity to weigh in on a matter of first impression, the Federal Circuit framed the issue before it as depending on “the proper interpretation of the term ‘ground’ used in” the IPR estoppel statute. The Court noted that while the Patent Act (35 U.S.C. § 100) does not expressly define “ground,” 35 U.S.C. §§ 311 and 312 use the term and illustrate its meaning.⁸

Regarding Section 311, the Court found that Section 311(b)’s limitation on the scope of IPRs to a “ground” that could be raised under Section 102 or 103 “makes clear that grounds are the theories of invalidity available to challenge a claim under §§ 102 and 103” — i.e., that the claimed invention was described in a patent or printed publication, known or used by others, on sale, or in public use before the date of the invention (pre‑AIA) or the effective filing date (AIA) (together, the “critical date”). But Congress went one step further, limiting the “grounds” available in IPRs to patents and printed publications. Thus, “[b]y design, a petitioner has no opportunity to challenge that the claimed invention was known or used by others, on sale, or in public use at IPR. . . . These are grounds that could normally be raised under §§ 102 and 103, but Congress excluded them in IPR proceedings.”⁹

The Court also confirmed that “a ground is not the prior art asserted during an IPR.”¹⁰ If Congress wanted to preclude petitioners from asserting in district court that a claim is invalid on any prior art that the petitioner raised or reasonably could have raised during an IPR, the Court reasoned, it would have done so. Instead, Congress precluded petitioners from asserting grounds in district court. Thus, “IPR estoppel does not preclude a petitioner from asserting the same prior art raised in an IPR in district court, but rather precludes a petitioner from asserting grounds that were raised or reasonably could have been raised during an IPR.” Said differently, “IPR estoppel does not preclude a petitioner from relying on the same patents and printed publications as evidence in asserting a ground that could not be raised during the IPR, such as that the claimed invention was known or used by others, on sale, or in public use.”¹¹

Because Ingenico had argued in district court only that the prior art flash drive device was known or used by others, on sale, or in public use before the claimed invention, and not that it was described in a patent or printed publication (despite relying on printed publications as evidence of its asserted grounds), the Court found that these were grounds that could not have been raised during the IPR and, thus, declined to apply IPR estoppel. Accordingly, the Court affirmed the district court’s denial of IOENGINE’s motion for a new trial.

What This Means for You

Ingenico provides long-awaited certainty regarding the scope of IPR estoppel in district court and ITC proceedings. Before, a patentee was left guessing how a district court would treat an accused infringer’s invalidity argument based on patents or printed publications that reasonably could have been raised in a prior IPR.

For example, a common invalidity argument raised in district court by accused infringers is that a claimed invention is obvious in view of a combination of prior art patents or printed publications (that reasonably could have been raised in a prior IPR) and device art. Before Ingenico, many district courts, like the District of Delaware in Prolitec,¹² held that IPR estoppel does not apply to device art at all, even when the device art is cumulative of the patents or printed publications, but not necessarily for the reasons set forth by the Federal Circuit in Ingenico.

Now, the analysis is straightforward — if the accused infringer relies on patents or printed publications that reasonably could have been raised in a prior IPR on the grounds that the claimed invention was described in patents or printed publications before the critical date, IPR estoppel will apply. To the extent the accused infringer relies on patents or printed publications that reasonably could have been raised in a prior IPR as evidence of other invalidity grounds — i.e., that the claimed invention was known or used by others, on sale, or in public use before the critical date, IPR estoppel will not apply.

¹ No. 23-1367 (Fed. Cir. May 7, 2025) (“Op.”).

² 35 U.S.C. § 311(b) (emphases added).

³ 35 U.S.C. § 315(e)(2) (emphasis added).

⁴ See Op. at 2–3.

⁵ Id. at 3.

⁶ Prolitec Inc. v. ScentAir Techs., LLC, No. CV 20-984-WCB, 2023 WL 8697973, at *22 (D. Del. Dec. 13, 2023).

⁷ Op. at 3–4.

⁸ See id. at 12.

⁹ Id. at 12–13.

¹⁰ The Court based its reasoning on Section 312(a)(3), which provides that “the evidence that supports the grounds . . . include[s]—(A) copies of patents and printed publications that the petitioner relies upon in support of the petition,” and determined that “while patents and printed publications are evidence that support a ground that the claimed invention was patented or described in a printed publication, they are not coextensive with a ground.” Id. at 14.

¹¹ Id.

¹² See 2023 WL 8697973 at *23 (“I . . . hold that IPR estoppel does not apply to device art, even when that device art is cumulative of patents and printed publications that were or could have been asserted in a prior IPR.”).