When IPR petitions assert too many grounds of unpatentability, the PTAB routinely declines to institute on some, declaring them redundant. Petitioners, fearful of having large portions of their work ignored as redundant, reduce the number of grounds asserted in one petition, sometimes filing different grounds in different petitions. And, when multiple grounds are offered for the same claim, petitioners have been cautioned to explain how their grounds raise different issues and are not redundant.

However, a recent decision—in which redundancy in a first petition helped the petitioner reach a decision on the merits in a second petition—may turn the strategy of avoiding redundancy on its head.

In Apotex v. WyethIPR2015-00873 (paper 8), the first petition resulted in institution and proceeded to a final written decision in which the claims were found not unpatentable. Grounds that were deemed redundant were dropped from the first IPR at the institution stage and were not substantively addressed during the ensuing IPR trial. The petitioner then re-filed them in a second petition along with other grounds.

The patent owner argued that the second petition was barred by estoppel, set forth in 35 U.S.C. § 315(e)(1). Estoppel bars a second petition “on any ground that the petitioner raised or reasonably could have raised during that inter partes review.” Undeniably, the petitioner could have raised the redundant grounds earlier, because they were actually asserted in the first petition. 

However, the PTAB interpreted the estoppel to apply to only those grounds that were or could have been addressed during the IPR trial. Because the petitioner had tried—and been thwarted by the PTAB’s prior finding of redundancy—to raise a ground, it could not have raised that ground during the trial. As a result, the petitioner was not estopped from trying to prove unpatentability in this second petition based on the redundant ground from the first petition. The petitioner was, however, precluded from raising in the second petition grounds that were not raised, but could have been, in the first petition. The PTAB viewed it as the petitioner’s choice not to raise these grounds, and the estoppel applied.

The practical impact at the PTAB of this decision may be small, even if adopted by other panels. Though the PTAB considered in the second petition the merits of the ground dismissed as redundant in the first petition, it reached the same conclusion on the merits: that the petitioner was unlikely to show the claims of the challenged patent were unpatentable in light of that ground. 

A far greater impact may be felt in district court litigation. The second half of 35 U.S.C. § 315(e) defines estoppel in district court in the same terms, applying it to “any ground that the petitioner raised or reasonably could have raised during that inter partes review.” If district courts interpret this section as the panel in Apotex did, estoppel will not apply to the redundant grounds, leaving open the possibility that, despite losing a bid to invalidate a patent in an IPR, a petitioner might re-litigate substantially the same issues, presented based on grounds deemed redundant in the IPR. As a result, this decision raises many questions that should be considered when crafting a petition with multiple grounds or challenging such a petition pre-institution.