Using Prosecution History in IPR: What You Say May Come Back to Help You

Prosecution history can be a minefield in patent cases, and IPR is no different. In the context of construing patent claims, much of the focus is often on whether the patent owner disclaimed particular subject matter from the scope of the claims. But two recent Federal Circuit decisions reviewing decisions in IPR illustrate that even absent disclaimer, patent owners may be able to save the challenged claims by pointing to their past statements during prosecution. In Personalized Media Communications v. Apple (No. 2019-1936), the relevant challenged claims concerned embedding information in broadcast transmissions. The PTAB had found the challenged claims obvious over a reference that disclosed mixed analog and digital signals, and the patent owner argued on appeal that the claims should be limited to digital-only signals. The Federal Circuit agreed with the patent owner, treating the patent owner’s statements during prosecution that limited the claimed technology to digital-only transmission as dispositive.

In Kaken Pharmaceutical v. Iancu (No. 2018-2232), the Federal Circuit again relied on prosecution history to limit the challenged claims, which concerned treating a fungal infection. The Board found the challenged claims obvious, relying on definitions in the specification that suggested that the treatment can occur in several ways. The patent owner argued on appeal that the claims should be limited to one particular way of treatment, and the Federal Circuit agreed because of the patent owner’s statements during prosecution limiting the claims.


  • These decisions illustrate that prosecution history can be relevant even when the patent owner has not disclaimed subject matter. Parties to IPR should keep in mind, however, that both cases concerned claims and specifications that did not directly resolve the claim construction dispute. Had the claims and specifications been clearer, prosecution history that does not rise to the level of disclaimer may not have been as relevant.
  • Prosecution history is one of several tools patent owners have to fight IPR petitions that rely on prior art that is similar to prior art relied on during prosecution. The PTAB has expressed some willingness to discretionarily deny petitions that do little more than rehash prior art discussed during prosecution. And these two decisions illustrate that the patent owners’ arguments during prosecution distinguishing such references may help to save the claims.
  • These decisions from the Federal Circuit are not all good news for patent owners. Although these cases were decided under the “broadest reasonable interpretation” standard, the principle they express may also apply to the scope of the claims for infringement purposes in District Court. Thus, while limiting the construction of claims based on prosecution history may preserve the claims during IPR, it may also give the petitioner a basis to avoid infringement. Patent owners need to consider infringement issues before commiting to a claim construction strategy in IPR.