The Patent Trial and Appeal Board (PTAB or Board) interpreted the estoppel provision of 35 U.S.C. § 315(e)(1) to deny institution of inter partes review in a second petition by the same petitioner against the challenged patent of ground that would have been raised in its earlier petition. Apotex Inc. v. Wyeth LLC, Case No. IPR 2015-00873 (PTAB, Sept. 16, 2015) (Kokoski, APJ).

The present IPR petition was the third that Apotex had filed with respect to the challenged patent. In its first petition and its current petitions, Apotex asserted that the challenged patent claims, which are “directed to compositions comprising tigecycline, a suitable carbohydrate, and an acid or buffer,” would have been obvious in view of the teachings of various prior art references. The Board had instituted an IPR on certain grounds urged in the first petition and ultimately issued a final written decision in that proceeding.

Apotex’s present petition sought institution of an IPR based on two grounds. Ground 1 was among those raised in the first IPR petition, but the Board declined to institute review on this ground, finding it cumulative. Ground 2 had not been raised in the initial petition, although the underlying references were all cited in that petition. The patent owner (Wyeth) argued that Apotex was estopped from asserting Grounds 1 and 2 based on § 315(e)(1), which precludes a petitioner in an IPR that resulted in a final decision from seeking or pursuing another IPR-based on “any ground that the petitioner raised or reasonably could have raised during [the first IPR].”

Based on the legislative history of the AIA, the Board interpreted the “could have raised” provision of § 315(e)(1) as including “prior art which a skilled searcher conducting a diligent search reasonably could have been expected to discover.” However, the Board found it unnecessary to apply this standard to the present case because Apotex “was aware of, and cited, all of the Ground 2 prior art in the [initial] Petition, and therefore reasonably could have raised it during that proceeding.”

In contrast, although Ground 1 was included in Apotex’s first IPR petition, the Board ultimately found that § 315(e)(1) did not bar Apotex from pursuing Ground 1 in the present proceeding. Section 315(e)(1) only applies to “grounds that the petitioner ‘raised or reasonably could have raised during the inter parties review.’” The Board explained that “[a]n inter partes review does not begin until the Office decides to institute review; prior to that point, our Rules refer to a preliminary proceeding that begins with the filing of a petition and ends with a decision whether to institute trial.” Accordingly, the Board explained that “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).” The Board went on to consider Ground 1 on the merits and ultimately denied Apotex’s petition on the grounds that Apotex had not established a reasonable likelihood that the challenged claims would have been obvious.

Practice Note: In view of the PTAB’s interpretation of the estoppel provisions of § 315(e)(1), petitioners run the risk of future estoppel by failing to include all references cited in an IPR petition as part of specific grounds for obviousness. Further, any grounds on which an IPR is not instituted are fair game for a subsequent IPR petition.