Anyone involved in patent litigation today is aware of the use of inter partes review (IPR) as a defensive tactic. Since 2012, the Leahy–Smith America Invents Act allows interested parties to petition the patent office to reconsider a patent’s validity. A successful petition can result in all or part of the patent being invalidated and quickly ending any pending and future lawsuits based on the patent. But there are limits to the effectiveness of an IPR. And depending on the court in which it is filed, an IPR can have drastic effects on district court lawsuits.

IPR is not available for every patent defense. Unlike defenses in a district court lawsuit, a request for the United States Patent and Trademark Office (USPTO) to institute an IPR must be based on patents or printed publications. An IPR cannot be used to raise invalidity defenses such as section 101 patentability or insufficient written description. Additionally, a defendant has to file an IPR within 12 months of being served with a lawsuit, but a potential defendant that files a declaratory judgment action cannot file an IPR. Even if a petition requesting an IPR is granted—and an IPR is instituted—a district court handling a case involving the same patent is not required to stay the lawsuit while the IPR is pending. Some courts typically refuse to stay cases in light of the delay caused by an IPR, while others are quick to grant a stay. A strong belief in our foundational jury trial system, and the speedy resolution of patent disputes, favors denial of stays.