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The scope of estoppel under the America Invents Act is becoming clearer in view of recent Federal Circuit and Patent Trial and Appeal Board (PTAB) decisions.  As discussed in our earlier article, the Federal Circuit has consistently held that estoppel does not apply to grounds of challenge that the PTAB did not institute for trial.  See, e.g., Shaw Indus. Grp., Inc. v. Automated Creel Sys., Inc., 817 F.3d 1293, 1300 (Fed. Cir. 2016).

35 U.S.C. § 315(e)(1) provides that if a petitioner challenges a claim of a patent in an inter partes review (IPR) proceeding that results in a final written decision, the petitioner, real party-in-interest or privy of the petitioner “may not request or maintain a proceeding before the Office with respect to that claim on any ground that the petitioner raised or reasonably could have raised during that inter partes review.”  Under 35 U.S.C. § 315(e)(2), the petitioner as well as its real party-in-interest and privy are similarly estopped from challenging the validity of a claim of a patent in district court or ITC litigation on any ground that the petitioner “raised or reasonably could have raised” during an IPR that resulted in a final written decision.  Similar estoppel provisions apply to post-grant review (PGR) proceedings under 35 U.S.C. § 325(e).

The PTAB has recently issued decisions that provide guidance on when estoppel applies to grounds of challenge that were “raised or reasonably could have been raised” during a previous IPR proceeding in which a final written decision was issued.

In Ford Motor Co. v. Paice LLC, IPR2015-00790, Paper 34 (PTAB Nov. 4, 2016), the PTAB panel held that the petitioner was estopped from maintaining a challenge for a claim in a subsequent IPR proceeding after the petitioner received a final written decision with respect to that claim in an earlier IPR proceeding.  The panel determined that the petitioner could not maintain its challenge of the claim because the prior art newly asserted in the second petition was cited during prosecution of the challenged patent and is listed on the face of the patent.  Id. at 7.  The panel therefore determined that estoppel applies because the petitioner could have reasonably raised that challenge in the earlier petition.

In another proceeding, Ford Motor Co. v. Paice LLC, IPR2014-00884, Paper 38 (PTAB Dec. 10, 2015), the petitioner was similarly estopped from challenging two claims in a later IPR proceeding based on prior art that was cited during the prosecution of the challenged patent, after the PTAB issued a final written decision with respect to those claims in an earlier IPR proceeding.  Id. at 13-14.  The PTAB panel explained that “[w]hat a petitioner ‘reasonably could have raised’ includes prior art that a skilled advocate would have been expected to discover and proffer in the course of conducting due diligence on the patent at issue.”  Id. at 14.  The panel determined that since the newly asserted prior art was cited during prosecution of the patent, the petitioner “must have known of [the newly asserted prior art] at the time of the [earlier] Petitions, and if not, such knowledge should be imputed to it.”  Id. at 14-15.

In Praxair Distribution Inc. v. Ino Therapeutics LLC, IPR2016-00781, Paper 10 (PTAB Aug. 25, 2016), the PTAB panel denied institution of a second petition filed against the challenged patent because the petitioner had received a final written decision addressing all of the claims of the patent in response to a first petition filed by the same petitioner.  In the second petition, the petitioner newly relied on two textbooks as prior art, and asserted that it was not aware of the newly asserted references despite conducting diligent searches of the prior art.  Id. at 8.  The panel determined that the petitioner did not “demonstrate[] that a skilled searcher conducting a diligent search would not have expected to discover [the textbooks].”  Id. at 10.  Importantly, the panel emphasized that it was the petitioner’s burden to demonstrate that it reasonably could not have presented the new textbook-based grounds of challenge in the first petition.  Finding that the petitioner did not meet its burden, the panel determined that the petitioner reasonably could have raised the textbook-based grounds of challenge in the first petition and was therefore estopped from bringing those grounds in the second petition.  Id.

The panel in Praxair noted that the petitioner’s assertion of a diligent search was predicated on a single search report by an unidentified searcher identifying a mere fifteen “exemplary” search results.  Id. at 9.  Further, the panel noted that the petitioner did not identify the searcher’s skill level and experience in the field, or the search parameters used during the search.  Id.  It appears that the petitioner’s characterization of the textbooks worked against the petitioner.  The petitioner and its expert characterized one of the textbook authors as being a “thought leader” in the field, and argued that both textbooks would be “part of a collected literature” regarding the technical focus of the patent.  Id. at 9-10.  These factors contributed to the panel determining that the petitioner reasonably could have raised the textbook-based challenges in the earlier petition.

In view of the Ford decisions, if a petitioner files a subsequent petition relying on prior art that was made of record during prosecution of the challenged patent, it appears likely that the PTAB will determine that the petitioner “reasonably could have raised” that prior art when it filed its initial petition.  In view of Praxair, a petitioner relying on new prior art to challenge the same claims for which a final written decision has been issued may wish to consider presenting arguments and evidence demonstrating that a skilled searcher would not have expected to discover the newly asserted prior art.  For example, the petitioner may wish to consider identifying the searcher, the searcher’s level of experience, and the parameters of the search.   In view of Praxair’s criticism of how the petitioner provided only a single search report, petitioners may also wish to consider submitting multiple search reports from different searchers.