It is not uncommon for a defendant in a patent infringement litigation to file a petition for inter partes review (IPR) before the Patent Trial and Appeal Board.¹ An important issue that arises when the PTAB denies institution of an IPR is whether the trial court will allow the patent owner to introduce evidence of that denial at trial.²

District court decisions have gone both ways on the issue, i.e., some district courts have allowed patent owners to introduce evidence of a decision to deny institution of an IPR, and some district courts have precluded such evidence.³ In an October 12, 2017, decision,⁴ the Eastern District of Wisconsin granted the defendant’s motion in limine to preclude the patent owner from introducing evidence concerning post-issuance proceedings involving the three patents in suit. One of the patents in suit was the subject of at least one ex parte reexamination, one inter partes reexamination (the pre-America Invents Act predecessor to inter partes review proceedings) and four IPRs. Each of the other two patents in suit was the subject of at least one inter partes reexamination and four IPRs.

The District Court first summarized its earlier ruling concerning prior art references/prior art combinations that Snap-On was estopped from relying on in the litigation. In its earlier order, the District Court determined that Snap-On was barred from relying on any prior art that Snap-On reasonably could have relied on — but did not — when it filed its IPR petitions; was barred from relying on any invalidity ground upon which the PTAB instituted trial; but was not barred from relying on any invalidity ground included in its IPR petitions upon which the PTAB did not institute trial.

In its motion in limine to preclude the patent owner from introducing evidence of the PTAB’s denial decisions, Snap-On argued that those decisions were irrelevant. Snap-On argued that because estoppel⁵ precluded it from relying at trial on any grounds ruled upon in the PTAB’s final written decision issued at the conclusion of the IPRs, the prior art references that Snap-On would introduce at trial would necessarily be different than those considered by the PTAB. Snap-On also argued that explaining to the jury the post-issuance PTO procedures, the relevant legal standards in those proceedings, the evidence the PTO considered in each proceeding, and the outcomes in each proceeding would waste the jury’s time, confuse the jury, and mislead the jury to defer to the PTAB on the issue of validity.

The patent owner countered that the PTO’s decisions upholding plaintiffs’ patents against post-issuance challenges were relevant to opposing Snap-On’s invalidity contentions because the PTO’s decisions showed that Snap-On was rehashing arguments that were already unsuccessful before the PTO. The patent owner also argued that the post-issuance proceedings provided context for the third-party license agreements plaintiffs intended to use to prove damages.

Ultimately the District Court agreed with Snap-On, finding particularly relevant the fact that estoppel prevented Snap-On from arguing invalidity based on prior art that was the subject of an instituted IPR proceeding. The court disagreed with other district courts that had determined that any prejudice resulting from a patent owner’s introduction of evidence of a PTAB denial decision could be remedied by a jury instruction explaining the different legal standards in the PTO and the court. The District Court concluded that the prejudice outweighed the probative value of the PTAB denial decisions. Therefore, the District Court ruled that the patent owner could not introduce evidence of the post-issuance proceedings where the PTO determined the patents in suit were not unpatentable, whether in a decision denying institution or a final written decision in the patent owner’s favor, and, similarly, Snap-On could not introduce evidence of any IPR institutions or favorable statements by the PTO during post-issuance proceedings. However, the District Court also ruled that “[t]he parties may … 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.”