The America Invents Act (“AIA) provided an accused infringer sued for patent infringement (“Patent Challenger”) with a new, alternative forum to challenge the patents asserted against them: inter partes review (“IPR”). In exchange—and to avoid duplicative parallel district court and Patent Office proceedings—the AIA provided upon a final written decision, the Patent Challenger would be estopped from asserting against any surviving claim an invalidity theory based “on any ground that the [Patent Challenger] raised or reasonably could have raised during that inter partes review.”[1]
In 2022, the Patent Office provided guidance encouraging Patent Challengers to embrace the AIA’s estoppel provision upon institution of an IPR, through use of a so-called Sotera stipulations.[2] Sotera[3] stipulations are used to influence the PTAB’s weighing of Fintiv factors—which take into account the timing of a parallel court action and potential for duplication as part of the PTAB’s analysis of whether to institute an IPR[4] Specifically, a Sotera stipulation is intended to address the Fintiv factor concerning the “overlap between issues raised in the petition and in the parallel proceeding.”[5] In effect, Sotera stipulations serve to assure the PTAB that where parallel litigation is likely to be resolved before a final written decision on the IPR would be due, if the PTAB institutes the IPRs, the Patent Challenger will not pursue estopped invalidity theories in the district court as the parallel litigation proceeds. If a Sotera stipulation is filed, the PTAB stated that it will not deny institution of an IPR under Fintiv.[6] Since then, Sotera stipulations have become increasingly commonplace.
As an example, in Sotera, the Patent Challenger’s stipulation stated:
[I]f the [PTAB] institutes IPR . . . Defendants will not pursue in [the District Court] the specific grounds [asserted in the inter partes review] in connection with the referenced patent(s) and claim(s) as originally issued on the instituted [IPR] petition, or on any other ground for a given patent for which the [PTAB] institutes, that was raised or could have been reasonably raised in an IPR. (i.e., any ground that could be raised under §§ 102 or 103 on the basis of prior art patent or printed publications).”[7]
Sotera stipulations may vary in form to some extent, but inclusion of the statutory “or could have been reasonably raised” language distinguishes a Sotera stipulation from other stipulations that the PTAB has accorded less weight.[8]
The scope of “or could have been raised” was subject to much dispute, but the Federal Circuit has clarified that IPR estoppel applies to any grounds a petitioner reasonably could have brought in an IPR.[9] This conclusion was further confirmed in response to a petition for certiorari Apple filed with the Supreme Court, where the Solicitor General took the position that the Federal Circuit’s interpretation is correct:[10]
The court of appeals correctly held that 35 U.S.C. 315(e)(2) bars petitioners from advancing invalidity grounds they knew or should have known about at the time they filed their petitions for inter partes review, yet omitted from their petitions.
Thereafter, in apparent agreement, the Supreme Court declined to grant certiorari to review the Federal Circuit’s interpretation.
On its face, the AIA’s estoppel provision—and Sotera stipulations—may seem to provide a broad benefit to a Patent Owner. In practice, however, determining the scope of IPR estoppel to invalidity grounds in litigation can be more complicated than it may seem for a variety of reasons:
- Burden of Proving IPR Estoppel. The Federal Circuit has held the burden to show IPR estoppel is on the Patent Owner, as the party asserting the estoppel.[11]
- Standard. The Patent Owner must show, by a preponderance of the evidence, that the Patent Challenger actually knew of the reference or if a skilled searcher conducting a diligent search reasonably could have been expected to discover the reference.[12] At least one district court has denied a summary judgment motion to enforce IPR estoppel because questions of fact remained as to whether the printed publication at issue could have been found by a skilled searcher.[13]
- Application of IPR Estoppel to Non-Instituted Claims. IPR estoppel can apply to claims that were not raised in the IPR.[14]
- Discovery of Privileged Materials. Whether a printed publication “could have been raised” may implicate privileged or work product materials. For example, written discovery requests seeking the date when counsel learned of each reference may be within the fair...
