By Barbara McCurdy and Arpita Bhattacharyya ( June 19, 2018, 1:38 PM EDT) -- The possibility of estoppel is an important consideration for a defendant in a patent infringement action in deciding whether or not to file an inter partes review petition. Indeed, it is well-known that upon issuance of a final written decision, the petitioner "may not assert in a civil action that the claim is invalid on any ground that the petitioner raised or reasonably could have raised during that inter partes review."[1] Two Federal Circuit decisions — Shaw and HP — had (temporarily) blunted the impact of this seemingly broad estoppel provision by determining that noninstituted grounds in an IPR petition are not subject to estoppel.[2] While at least one district court has limited Shaw and HP to their facts and exempted only grounds that were not instituted for procedural reasons (such as redundancy), other district courts have exempted all noninstituted grounds from estoppel irrespective of the reason for noninstitution.[3]...