Defining "Privy"

By Eugene T. Perez and Kelly E. Rose

The estoppel provisions in AIA 35 U.S.C. §§ 315(e) and 325(e) impose limits on serial challenges to patents by estopping a petitioner from challenging a patent based on  issues that were raised or reasonably could have been raised in a prior challenge.1  These provisions extend to both real parties in interest and their privies.  While determining who the real party in interest is presents its own challenge, determining whether a party is a “privy,” and thus estopped, may be equally if not more difficult.  For a more substantial analysis of the “real party in interest,” click here.

Neither the AIA nor the corresponding rules by the United States Patent and Trademark Office (the “USPTO”) provide a definition for “privy.”2  The Practice Guide for Proposed Trial Rules has stressed that the question of whether a non-party is a “privy” is a “highly fact dependent question” that will be handled on a “case-by-case basis.”3  A common consideration is whether the non-party exercised control over a party’s participation in a proceeding.4  However, the USPTO has been careful to note that there is no bright-line test for determining the requisite degree of participation.5  In response to comments requesting a more concise definition of “privy,” the USPTO restated that “privity is determined on a case-by-case basis . . . whether a requester is a privy to an estopped party must be decided by evaluating all the facts and circumstances of each individual situation.”6     

To the extent that statutory interpretation may play a role in defining privies, the legislative history is not particularly elucidating. Senator Kyl remarked that “privity is an equitable rule that takes into account the “practical situation,” and should extend to parties to transactions and other activities relation to the property in question.”7  Senator Kyl further suggested that privity estoppel may extend to codefendants.8  Additionally, Senator Schumer discussed the term “privy” specifically in relation to Section 18 of the AIA, which allows a party to file a petition for a transitional post-grant review proceeding for covered business method patents if either that party or its real party in interest or its privy has been accused of infringement.9  Senator Schumer explained that a “privy is a party that has a direct relationship to the petitioner” and “it effectively means customer of the petitioner.”  Although speaking only on the topic of Section 18 proceedings, Senator Schumer comments may provide some insight on whether a non-party is a “privy.”

As a fact-intensive inquiry itself, further guidance for determining whether privity estoppel is applicable to non-party lies with future Patent Trial and Appeal Board/Federal Circuit decisions.


  1. Leahy Smith America Invents Act, Pub. L. No. 112-29 (“AIA”), § 315(e) and § 325(e)
  2. Vol. 77, No. 157 Fed. Reg. 48680, 48694-48695 (August 14, 2012)
  3. Practice Guide for Proposed Trial Rules, 77 Fed. Reg. 6868, 6870 (February 9, 2012) (citing Taylor v. Sturgell, 553 U.S. 880, 895 (2008))
  4. Id.
  5. Id.
  6. Changes to Implement Miscellaneous Post Patent Provision of the Leahy-Smith America Invents Ac, 77 Fed. Reg. 46615, 46622 (August 6, 2012).
  7. 112 Cong. Rec. S1376 (daily ed. March 8, 2011) (Senator Kyl Remarks).
  8. Id.
  9. 112 Cong. Rec. S5432 (daily ed. September 8, 2011) (Senator Schumer Remarks).