IPR Estoppel May Apply to Product-Based Defenses

Under the estoppel provisions of 35 U.S.C. § 315(e), if an IPR results in a final written decision, the petitioner is barred from raising invalidity arguments in court or the ITC based on any grounds the petitioner “raised or reasonably could have raised” in the IPR, which may in practice mean any grounds based on patents or printed publications. Thus, petitioners involved in parallel litigation sometimes assert backup invalidity defenses based on prior art products. Two recent cases demonstrate that while such defenses can avoid estoppel, courts may reject perceived attempts to dodge estoppel by simply repackaging a publication-based ground as a product-based ground.

In Polaris Industries v. Arctic Cat (D. Minn.), Polaris moved for summary judgment that IPR estoppel barred Arctic Cat from pursuing seven invalidity grounds: three involving physical vehicles, and four involving publications—including the vehicle manuals—and patents. The court estopped the latter grounds but not the former. It rejected Polaris’s argument that estoppel should apply to the vehicle-based grounds because the vehicle manuals disclosed everything relevant, noting that no previous case had applied estoppel to products.

The next day, however, in CalTech. v. Broadcom (C.D. Cal.), the court suggested that estoppel could apply to products in certain circumstances. The plaintiffs sought to apply IPR estoppel to invalidity defenses under the “known or used” prong of pre-AIA Section 102(a) that relied on public presentations as evidence. The court held that there must be “some substantive difference” (emphasis in original) between the “known or used” evidence and any related patents/publications that would be estopped. In so ruling, the court relied on prior cases suggesting that estoppel might prohibit relying too heavily on published product manuals as evidence of what a product disclosed. It ruled that defendants could not use publicly presented papers or slides as “primary” evidence for what was “known or used,” but could use them to corroborate “other evidentiary sources.” The court ultimately estopped the defenses based on the lack of timely produced evidence meeting the “some substantive difference” test.


Petitioners asserting backup product-based defenses should look for admissible evidence of a product’s structure/operation that provides some relevant information beyond the published documentation. Depending on the challenged claim and the products, such evidence might include screenshots or other demonstrations of the product, laboratory testing reports, or non-public technical documentation. Published manuals may be safe to use as corroboration, but not as primary evidence.