July 6, 2015
35 USC §315(e)(2) prohibits a petitioner (or real party in interest or privy of the petitioner) in an Inter Partes Review (IPR) of a patent claim from asserting in district court litigation that “the claim is invalid on any ground that the petitioner raised or reasonably could have raised” during the IPR proceeding. This statutory IPR estoppel attaches as soon as the Patent Trials and Appeals Board (“PTAB”) renders a final written decision in an IPR proceeding.  

Although the PTAB has issued over 200 final written IPR decisions triggering estoppel in a parallel district court action since the introduction of the process in 2012, there is yet to be seen any real guidance from the district courts as to what constitutes a ground that “reasonably could have” been raised by a petitioner. Despite the lack of case law on what “reasonably could have” been raised means, we do have some guidance available to us outlining relevant exceptions to the could-have-raised estoppel.

For additional analysis, including grounds that have been determined to be likely possibilities for a petitioner to raise in a subsequently filed district court proceeding if omitted from the IPR, please click here.