In Praxair Distribution, Inc. v. INO Therapeutics, LLC., IPR2016-00781, Paper 10 (Aug. 25, 2016), the Board denied Praxair’s inter partes review petition based on both estoppel under 35 U.S.C. § 315(e)(1) and the PTAB’s discretion under § 325(d).

The petition challenged the same claims of U.S. Patent No. 8,846,112 as a prior petition filed by Praxair, but based on two new textbook references. Praxair asserted that it did not cite the new references in the earlier IPR because it did not discover them before filing. As evidence, Praxair provided a list of exemplary search results from Cardinal Intellectual Property, Inc.

The Board based its estoppel determination on whether the new references were “prior art which a skilled searcher conducting a diligent search reasonably could have been expected to discover.” The Board found the single search report insufficient to show that a reasonable search was conducted, highlighting the following facts:

  • The report was by an “unidentified searcher of indeterminate skill and experience”
  • The report does not explain why the searcher “used certain keywords and keyword combinations”
  • The report was an “exemplary list”, and Praxair did not “explain whether [the new references] were encompassed by the initial search results but not selected for the exemplary list”
  • The “other articles by the author . . . were cited during prosecution” and obviousness testimony of Praxair’s expert suggested that a person of ordinary skill in the art would have sought out the new references.

The Board also exercised its discretion to deny Praxair’s petition under § 325(d). They reached this conclusion not only because “the same or substantially the same arguments” were previously presented but also because Praxair “should have been aware of the newly-cited . . . references when it filed the earlier Petition.”