IPR Estoppel Might Not Be So Scary

The rules for post-grant proceedings established by the America Invents Act (AIA) provide that once the Patent Trial & Appeal Board (Board) renders a final written decision, a petitioner in an inter partes review (IPR) is prohibited from raising before the patent office, a district court, or the International Trade Commission "any ground that the petitioner raised or reasonably could have raised during that inter partes review."1 Initially, many believed that such broad estoppel provisions would deter parties from considering such post-grant proceedings.

In this regard, there has been much uncertainty about how courts will apply the IPR estoppel provisions of 35 U.S.C. § 315(e)(1) and whether a petitioner will be estopped in a subsequent IPR from raising grounds deemed "redundant" (i.e., multiple, similar arguments challenging the patentability of the same claims within an IPR) in a previous IPR.2

The Board has established that, absent a showing that newly cited prior art was "unknown or unavailable" at the time of filing a first petition, "a reasonable inference that those references were known or available" can be made when considering a second petition.3 The Board has also stated in dicta that, "could have raised" includes "prior art which a skilled searcher conducting a diligent search would reasonably ... have been expected to discover."4 Those decisions emphasized the importance for petitioners to present their best art when filing an IPR petition.

A recent decision by the Board has shed some light on the matter.5 Petitioner filed a second IPR petition following an adverse final written decision in a first IPR that was also filed by Petitioner on the same patent. Using combinations of cumulative art, the first IPR petition raised seven grounds of unpatentability based on obviousness, but the proceeding was instituted under only one of those grounds on the basis that the others were redundant. In response to the second IPR petition, the Board determined that Petitioner was estopped under 35 U.S.C. § 315(e)(1) from raising a new ground for invalidity based on obviousness (Ground 2) because, at the time of the first IPR petition, Petitioner was aware of, and indeed cited, all the same prior art as Ground 2. As a result, the Board concluded that Petitioner reasonably could have raised Ground 2 during that proceeding and, having failed to do so, was prohibited from raising it in the second IPR petition.

Conversely, the Board determined...