By: Tom Ritchie and John Marlott Petitioner Estoppel

There is no doubt that “the potential for estoppel is one of the important considerations for defendants in deciding whether or not to file an [inter partes review (“IPR”)] petition.”  Shaw Indus. Grp., Inc. v. Automated Creel Sys., Inc., 817 F.3d 1293, 1305 (Fed. Cir. 2016) (Reyna, J., concurring).  For IPR petitions that result in a final written decision, the America Invents Act prohibits the petitioner from asserting invalidity in a civil action “on any ground that the petitioner raised or reasonably could have raised during that inter partes review.”  35 U.S.C. § 315(e)(2).  Although the statutory estoppel language is seemingly straightforward, the issue of whether a petitioner “reasonably could have raised” a prior art ground during the IPR remains a source of uncertainty.

Recall that, in Shaw , the Federal Circuit ruled that estoppel does not attach to non-instituted grounds—that is, grounds raised by the petitioner in an IPR petition but not instituted for review by the PTAB.  Shaw, 817 F.3d at 1300; see also prior post on Shaw.  The Court reasoned that the petitioner “did not raise—nor could it have reasonably raised—the [non-instituted] ground during the IPR,” because “[t]he IPR does not begin until it is instituted.”  Id. (emphasis added).  The Federal Circuit’s holding in Shaw was thus directed to non-instituted grounds.  But what about prior art grounds not put forward by the petitioner in an IPR petition?  Lower courts have reached differing conclusions about whether the reasoning of Shaw also extends to grounds not raised in the IPR petition (“non-petitioned grounds”).

Recently, in Koninklijke Philips N.V. v. Wangs Alliance Corp., the district court addressed the scope of estoppel with respect to non-petitioned grounds.  No. CV 14-12298-DJC, 2018 WL 283893 (D. Mass. Jan. 2, 2018).  In a  motion for summary judgment, the plaintiffs argued that the defendant “reasonably could have raised” grounds in its IPR petition based on prior art references that the defendant had identified in invalidity contentions served in the underlying litigation before the petition was filed with the PTAB.  In reaching its decision, the district court focused on “whether the phrase ‘during inter partes review’ means only that portion of the IPR proceedings after the review is instituted, or whether it means the entirety of the IPR proceedings, including the initial filing of the petition.”  Id. at *3.  Although the court found “much appeal in a broader reading of the estoppel provision,” the court concluded that Shaw was binding and settled the question.  The phrase “during inter partes review” limits estoppel to the grounds actually raised during the period of time after an IPR is instituted.  Accordingly, the court denied the motion seeking to estop the defendant from asserting invalidity based on non-petitioned grounds.

In contrast, in Oil-Dri Corp. of Am. v. Nestle Purina Petcare Co., a different district court recently held that similar facts warranted estoppel for non-petitioned grounds.  No. 15-CV-1067, ECF No. 224 (N.D. Ill. Jan. 16, 2018).  In response to the plaintiff’s requests for admission, the defendant admitted that it had a copy of the prior art references at issue before filing its IPR petition.  The district court found this admission dispositive of the plaintiff’s renewed motion seeking to estop the defendant from asserting invalidity based on those references.  (The plaintiff’s earlier motion in this matter was also discussed in a prior post on motion regarding petitioner estoppel.)  The district court commented that “for IPR to fulfill its mission of streamlining patent litigation in the district courts and promoting efficient dispute resolution, a petitioner cannot be left with the option to institute a few grounds for IPR while holding some others in reserve for a second bite at the invalidity apple once in the district court.”  Id. at 4 (quoting Milwaukee Elec. Tool Corp. v. Snap-On Inc., 271 F. Supp. 3d 990, 1029 (E.D. Wis. 2017)).  Therefore, the court granted the motion for estoppel.


District courts do not agree on the scope of estoppel with respect to non-petitioned prior art grounds, and the Federal Circuit has not yet addressed this split of authority.  Given the uncertainty, petitioners and patent owners should consider their litigation strategies carefully while awaiting further development of the case law on this important issue.  Petitioners, in particular, should be mindful that “a second bite at the invalidity apple” may be unavailable for prior art grounds that were known and reasonably could have been raised in an IPR petition, but were not.

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John Marlott brings more than 30 years of intellectual property law experience to his role as lead counsel in IP disputes for Jones Day clients. He focuses on high-stakes district court and ITC patent litigation, post-grant patent proceedings before the PTAB, and appeals to the U.S. Court of Appeals for the Federal Circuit.

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