The PTAB does not appear to have weighed in, one way or another, on the question of how many references is too many for an obviousness challenge under 35 U.S.C. § 103—at least not explicitly.  Implicitly, the PTAB has regularly instituted inter partes review of patents where four or more references have been used to attack an independent claim.

A 1991 Federal Circuit case, In re Gorman, 933 F.2d 982 (Fed. Cir. 1991), rejected an argument that the combination of a large number of references “of itself weighs against a holding of obviousness.”  The Patent Office has also weighed in on the matter, saying that “reliance on a large number of references in a rejection does not, without more, weigh against the obviousness of the claimed invention.”  MPEP § 707.07(f).  However, there appears to be some skepticism of these holdings, post-KSR, as 717Madison Place and Patently-O consider “whether it is time to revisit In re Gorman.”  In particular, at the blog 717Madison Place, several highlights of oral argument are presented from recent cases, including questioning by Judge Moore that is highly skeptical of “four reference obviousness rejections”:

Judge Moore:  The question I asked is actually quite personal.  How often have you seen a four reference obviousness rejection; because, I never have.  Not out of the PTO.  Never.  I’ve seen people try to argue it in litigation, sure.  But, I’ve never seen the PTO go to four separate references and cherry pick items and then combine them together.

As a practical matter, going to a jury with four or more references is a challenging undertaking.  However, given the technical experience and more detailed patent knowledge of PTAB judges, one might reasonably expect such arguments to fare better in front of the PTAB.  And indeed, notwithstanding this skepticism noted above, the PTAB actually institutes on four reference obviousness grounds regularly.  For example, in Garmin International Inc. v. Cuozzo Speed Technologies LLC, IPR2012-00001 – the very first IPR filed – the PTAB instituted obviousness grounds over three- and four-reference combinations.  More recently, other panels have instituted on four or more reference combinations, including, e.g., IPR2016-01612 (four references, Feb 27, 2017), IPR2016-01412 (four references, Feb 14, 2017), IPR2016-01289 (four references, Dec 27, 2016), IPR2016-0118 (four+ references, Dec 23, 2016), and IPR2016-01370 (four references, May 2, 2016).

Even when the PTAB disregards one of the references presented in a multi-reference ground, the PTAB may still institute over the remaining references.  For example, in Geox S.p.A v. Outdry Technologies Corporation, where four references were presented in a ground, the PTAB disregarded one of the references the PTAB considered to be in a different field of endeavor than the other references.  IPR2014-01244, Institution Decision, Paper 5, at 4, 7, 8 (December 19, 2014).  However, despite not considering all the references presented in the ground, the PTAB still instituted on the challenged claims noting that the petition demonstrated a reasonable likelihood that the challenged claims were obvious over the combination of the remaining references.  Id. at 8.  Thus, the Geox case, in addition to the other cases highlighted above, indicates that there is low risk in pursuing multi-reference grounds.  However, when using multiple references, the petitioner should (1) make sure that the references support or complement one another rather than contain disclosures that teach away; and (2) highlight, if possible, where a claimed feature is taught by more than one reference to reduce the risk of being denied institution should the PTAB choose to disregard one of the references.

To be clear, the PTAB does sometimes deny institution of multi-reference obviousness grounds.  However, to our knowledge, the PTAB has never used the number of references as a factor in such denial.  Usually, the fault is that the Petitioner has used conclusory statements, or lacked a detailed obviousness analysis that includes specifying the scope of the prior art, differences with the claimed invention, and especially a motivation to combine references.  A typical example of this can be found in IPR2015-02007, where the Board faults the Petitioner, inter alia, for “various vague conclusions regarding alleged reasons to combine that do not specify which elements Petitioner is proposing to combine to reach the claim elements.”  IPR2015-02007, slip op. at 8.

Unfortunately, clear statistics of PTAB institution practice are hard to come by.  None of the USPTO, Docket Navigator, or Lex Machina, collect statistics or make it easy to search cases by the number of references on which an obviousness challenge was instituted or denied institution.  Other factors also make it harder to get a clear picture on how the Board views multi-reference obviousness grounds, such as the Board denying institution on multi-reference combinations as redundant to other grounds.  A detailed analysis of institution decisions, determining how often four or more references are granted or denied institution, would be useful.  However, lacking such a detailed analysis, we have conducted a quick study of recent institution decisions and found the following rough impression of recent PTAB activity.

In just the past six months, the PTAB has reviewed over 750 petitions for inter partes review that included an obviousness challenge under 35 U.S.C. § 103.  While most of the challenges relied on two- and three-reference combinations, there were still a significant number of petitions, nearly 200, that comprised obviousness grounds based on four or more references.  From the figure below, which details the number of references used in each petition (where a petition may include multiple grounds), the number of references used does not appear to correlate to the PTAB’s decision to institute or not institute a particular ground.  This recent data indicates that petitioners should not shy away from asserting obviousness challenges based on multiple references.

*Data collected from inter partes review institution decisions with an order filing date between September 10, 2016 and March 10, 2017.