315(e) Estoppel as an Affirmative Defense

As most are aware, completed AIA trial proceedings have estoppel consequences for failed petitioners.  For example, an unsuccessful Inter Partes Review (IPR) petitioner of a given patent claim, real party in interest, or privy of the petitioner, is estopped from asserting that the same claim is invalid in a civil or ITC action on any ground that the petitioner raised or reasonably could have raised during the failed IPR. (35 U.S.C. § 315 (e)(2)). The same estoppel applies to requesting or maintaining a proceeding before the USPTO with respect to such a claim (35 U.S.C. § 315(e)(2)).  As can be appreciated from this statutory framework, whether before the courts or the Patent Trial & Appeal Board (PTAB), Congress was clearly interested in preventing patent challengers from getting the proverbial second bite at the apple.

Occasionally, however, a petitioner will uncover new prior art that could not have reasonably have been raised in the earlier PTAB proceeding  Petitioners seeking to overcome the affirmative defense of statutory estoppel may find that the courts are far more receptive in this regard than the PTAB.

First, courts tend to be far stricter in the application of equitable defenses. While 315(e)(2) estoppel is a different animal than equitable estoppel, courts are as yet uncomfortable with its application. As demonstrated in at least one case, Clearlamp, LLC. v. LKQ Corp. Case No. 12 C 2533 (N. D. Ill. 2016) (here), not only is it the proponent of the estoppel (patentee) that bears the burden of proof, but that burden can be quite significant.  In the case of newly uncovered prior art, the court held that a patentee should, for example:

1) Identify the search string and search source that would identify the allegedly unavailable prior art; and
2) Present expert testimony why such a criterion would be part of a skilled searcher’s diligent search.

That is, the patentee, as the proponent of the affirmative defense bears the burden of proving the previous effort deficient to benefit from 315(e)(2) estoppel.

The PTAB on the other hand, takes a more patentee friendly view.  For example, in Praxair Distribution, Inc. v. Ino Therapeutics LLC (IPR2016-00781) (Paper No. 10, August  25, 2016) the Board looks to the petitioner to disprove the applicability of 315(e)(1) estoppel, explaining:

On the record before us, we, therefore, find scant evidence that [Petitioner] engaged ‘a skilled searcher conducting a diligent search’ as contemplated in the legislative history.  . . . . we are not persuaded that Petitioner has demonstrated that a skilled searcher conducting a diligent search would not have expected to discover [new references]

(emphasis added)

Unlike the courts, the Board as the arbiter of the first failed effort is far more comfortable denying follow-on requests.  Indeed, this is even the case where estoppel is not implicated, such as where the first request failed at institution.  Conopco, Inc. dba Unilever v. The Procter & Gamble Company IPR2014-00628, Pet.  Req. for Reh’g Denied, Paper 23, March 20, 2015 (here)

Given the differing institutional perspectives, failed IPR petitioners are better served raising the new art in the courts as compared to the PTAB.