IPR Estoppel Does Not Apply to Cumulative Prior Art

The court granted defendant's motion for summary judgment that plaintiff's headlamp salvage patent was invalid as obvious and rejected the argument that 35 U.S.C. § 315(e)(2) estopped defendant from asserting certain prior art. "[T]he datasheet can be used in civil litigation only if it could not have been found by a skilled searcher performing a diligent search. . . . In arguing that it performed an adequate search, [defendant], at least initially, takes on an unnecessary burden. It is the proponent of an estoppel argument that bears the burden. . . . One way to show what a skilled search would have found would be (1) to identify the search string and search source that would identify the allegedly unavailable prior art and (2) present evidence, likely expert testimony, why such a criterion would be part of a skilled searcher’s diligent search. . . . [Plaintiff], in fact, has performed step one with respect to two other pieces of prior art that [defendant] argues invalidates the asserted claims. It has not, however, done so with respect to [the datasheet]. As such, [plaintiff] is left arguing that a skilled searcher’s diligent search would have found cumulative pieces of prior art . . . [M]erely being cumulative of other prior art does not invoke § 315(e)(2) estoppel."

Clearlamp, LLC v. LKQ Corporation, 1-12-cv-02533 (ILND March 18, 2016, Order) (Lefkow, J.)