The Federal Circuit recently declined to consider whether a successful IPR petitioner is estopped from making its winning invalidity arguments in district court. If a winning petitioner does face estoppel, its arguments may be limited to those which could not have been brought through IPR when parallel litigation on the same patent proceeds pending rehearing or appeal of the IPR decision. This view of estoppel would shake up the carefully choreographed interplay between district court litigation and FDA approval of a generic manufacturer’s ANDA envisioned by the Hatch-Waxman Act. However, in BTG International Ltd. v. Amneal Pharmaceuticals LLC, the court found the issue moot after upholding the PTAB’s decision finding the challenged claims obvious.
A recent district court decision illustrates that petitioners should think carefully about requesting IPRs of claims that they may challenge as indefinite in litigation. Indefiniteness challenges are not permitted during an IPR. However, a PTAB decision during IPR may influence a district court’s ruling on an indefiniteness challenge raised in the litigation.
An IPR petitioner may, by request, and at the PTAB’s discretion, join another party’s prior filed IPR . A petitioner may seek to join an IPR to avoid the bar to filing more than one year after service of a complaint alleging infringement or to ensure the petitioner can continue its IPR if the parties to the prior filed IPR settle. If the petitioner’s challenge is substantially the same as that in the earlier IPR, it weighs in favor of joinder . Parties often copy the petitions from prior filed IPRs to facilitate joinder.