Inter partes review (IPR) proceedings have become a popular option for those seeking to invalidate a patent; however, the USPTO has been relying on the concept of “redundancy” to reduce the number of grounds of invalidity considered during a given review. Because estoppel attaches upon an IPR final decision with respect to any issue a petitioner reasonably could have raised, redundancy is proving a challenging consideration for IPR petitioners. In an August 11, 2014 article on CorpCounsel.com, Justin Oliver and Chitra Kalyanaraman examine the conflict between estoppel and redundancy.