A recent Delaware district court decision narrowly interpreted the estoppel provision of an Inter Partes review (IPR) to not include prior art and arguments that could have been raised, but were not raised by the Petitioner in the IPR. Intellectual Ventures I LLC v. Toshiba Corp., Civil Action No. 13-453, Slip Op. (DN 559) at 25–27 (D. Del. Dec. 19, 2016) (Memorandum Opinion).
Judge Robinson, arriving at the narrow interpretation first looked to the statutory language of 35 U.S.C. § 315(e)(2), which states in relevant part: “[t]he 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) … may not assert  in a civil action arising in whole or in part under section 1338 of title 28 … that the claim is invalid on any ground that the petitioner raised or reasonably could have raised during that inter partes review.”
Recognizing that the prior art and arguments at issue could have reasonably been raised by the Petitioner in the IPR, and under the statute the Petitioner would be estopped from raising them in the district court case, Judge Robinson looked to the Federal Circuit’s literal interpretation of the above language and found no estoppel. Particularly, in Shaw Indus. Grp., Inc. v. Automated Creel Sys., Inc., 817 F.3d 1293 (Fed. Cir. 2016), the Court determined that because PTAB did not institute an IPR on a particular ground the Petitioner “did not raise – nor could it have reasonably raised – the [rejected] ground during the IPR.”
Finding no estoppel, Judge Robinson stated: “Although extending the [Federal Circuit’s] logic to prior art references that were never presented to the PTAB at all (despite their public nature) confounds the very purpose of this parallel administrative proceeding, the court cannot divine a reasoned way around the Federal Circuit’s interpretation in Shaw.”
I predict this decision will be appealed to the Federal Circuit to weigh in on estoppel when prior art could have been, but were not raised by the IPR Petitioner. Nevertheless, as it stands now, at least in the District of Delaware, the estoppel provision does not seem to apply in such circumstances.