In an opinion dated October 12, 2017, the U.S. District Court for the Eastern District of Wisconsin granted a motion in limine to exclude evidence that a challenged patent had survived twenty post-issuance proceedings, including inter partes review (“IPR”) proceedings. The opinion (Milwaukee Electric Tool Corp. v. Snap-On Inc., No. 14-CV-1296-JPS, ECF No. 277 (E.D. Wisc. Oct. 12, 2017)) is a recent addition to the collection of district court opinions that are split on this issue, and provides a detailed analysis in support of decisions favoring exclusion.

With regard to pending IPR proceedings, the Federal Circuit has noted that “[i]t is generally true that evidence of non-final reexamination determinations is of little relevance and presents a risk of jury confusion.” K-TEC, Inc. v. Vita-Mix Corp., 696 F.3d 1364, 1376 (Fed. Cir. 2012). However, the admissibility of evidence relating to concluded IPR proceedings was deemed more of an open question. In StoneEagle Servs., Inc. v. Pay-Plus Sols., Inc., No. 8:13-cv-2240-T-33MAP, 2015 BL 196583 (M.D. Fla. June 19, 2015), the court cited multiple cases in which admissibility of such evidence was denied, but declined to follow the cited decisions, concluding that concerns regarding jury confusion could be alleviated through jury instruction. Id. at *9. By contrast, Wis. Alumni Research Found. v. Apple, Inc., 135 F. Supp. 3d 865, 875 (W.D. Wis. 2015) acknowledged the decision in StoneEagle and others like it, but concluded that risk of unfair prejudice and jury confusion substantially outweighed the probative value.

At issue in Milwaukee Electric was the alleged infringement by Snap-On of three patents (US 7,554,290, US 7,999,510, and US 7,944,173), which are directed to lithium-ion battery packs for use in power tools. The court acknowledged that, as none of the twenty post-issuance proceedings had resulted in invalidation, “Plaintiffs understandably want to explain that fact to the jury.” The court also acknowledged decisions on the subject by both StoneEagle and WARF. In siding with cases that favored exclusion of evidence relating to post-issuance proceedings before the PTAB, the court relied heavily on the estoppel effects of IPR proceedings. In particular, the court noted that “[b]ecause of the effect of IPR estoppel, the IPRs necessarily covered different prior art than will be used at trial. Whether that prior art was sufficient to invalidate the patents, as a general proposition, is irrelevant to the specific prior art at issue here.”

The court did make one notable exception to the exclusion. Specifically, the parties were permitted to “use as evidence statements made or evidence proffered during the [post-issuance proceedings] so long as this is done without referencing either the [proceedings] or the outcomes.”


When selecting venue for a patent infringement suit, it could be worth considering whether a local jurisdiction has decided to admit or exclude evidence of IPR victories, particularly if the patent owner’s victories are numerous and/or against the alleged infringer, at least until the split is resolved by the Federal Circuit.