In ruling on a “follow-on” inter partes review (IPR), the PTAB held that estoppel under 35 U.S.C. §315(e)(1) does not extent to grounds set forth in a petition that are denied as being redundant to a previous IPR proceeding. Apotex Inc. v. Wyeth LLC, IPR2015-00873, Paper 8 (P.T.A.B. Sept. 16, 2015).
The Facts. Apotex filed a petition to institute an IPR. Wyeth, the Patent owner, argued that Apotex was estopped from using certain prior art that it raised in a previously rejected petition challenging the same patent. Specifically, Wyeth argued that “Ground 1” in the instant petition was the same as “Ground 6” of a previous petition, which had been rejected. But in the previous petition, the PTAB denied the petition with respect to Ground 6 only because it was redundant to other arguments set forth in the petition, and the Board did not issue a final decision on Ground 6.
The Ruling. The PTAB held that because it had not reached the merits of the grounds at issue when deciding whether to institute a trial in the first petition, the petitioner was free to pursue those grounds in a subsequent petition. The PTAB first noted that “the estoppel provisions of 35 U.S.C. § 315 (e)(1) apply only to grounds that petitioner ‘raised or reasonably could have raised during [the] inter partes review.’” IPR2015-00873, pg. 8 (emphasis in the opinion). The PTAB then concluded that inter partes review does not begin until the Board institutes review, such that everything preceding the order institution IRP is a “preliminary proceeding” that is not subject to estoppel under the statute. “Therefore, grounds raised during the preliminary proceeding, but not made part of the instituted trial, are not raised “during” an inter partes review and cannot be the basis for estoppel under 35 U.S.C. § 315 (e)(1).” Id. at 8-9.
Implications. When Congress created the estoppel provisions in the America Invents Act in 2011, the legislation was intended to provide “a speedy and inexpensive alternative to typical federal patent litigation.” Estoppel was meant to prevent parties from raising any ground that it had previously raised or reasonably could have raised in an IPR. This opinion could prevent that if the PTAB permits petitioners to raise prior art that a previous Board has found redundant, since it could result in successive IPR petitions that draw out the process. It could also influence how federal courts look at what grounds and evidence are precluded from litigation after an IPR challenge.
 For an interesting discussion of inter partes review estoppel provisions, see Ann E. Motl, Note: Inter Partes Review: Ensuring Effective Patent Litigation Through Estoppel, 99 Minn. L. Rev. 1975 (2015).