The U.S. District Court for the District of Massachusetts recently found [1] that the scope of inter partes review estoppel was limited to only those grounds specifically instituted in an IPR proceeding, applying the standard set forth by the Federal Circuit in Shaw [2]. Following a final written decision invalidating some, but not all, asserted claims, patent owner Philips Lighting sought to preclude defendant WAC Lighting from asserting any ground of invalidity identified in WAC’s invalidity contentions in the district court litigation.

The court denied Philips’ motion to exclude the invalidity theories WAC disclosed in its invalidity contentions but did not include in its petitions for IPR. The court recognized that a narrow reading of Shaw may encourage the petitioner/defendant to engage in “gamesmanship” and thereby “constrain[] the potential of any such stay [of the underlying litigation] to narrow the issues before this Court.” However, while acknowledging that there is “much appeal in a broader reading of the estoppel provision” of 35 U.S.C. § 315, the court concluded that any “broader reading of the estoppel provision is foreclosed by Shaw.”

Some district courts have found that IPR estoppel applies only to petitioned-for but non-instituted grounds. However, in districts that follow this decision’s narrower view of the Shaw holding, defendants are provided with a “safety valve” in the event that an invalidity challenge before the PTAB fails.