Available since September 2012, inter partes review (IPR) is a procedure in which the validity of an issued U.S. patent can be challenged before the Patent and Trademark Office. Due to their relatively low cost (compared to district court litigation) and the petitioner’s high likelihood of success, IPRs have become a popular mechanism for invalidating patents in the United States.

The IPR procedure has two steps: a preliminary phase and a trial phase. The preliminary phase begins with the filing of a petition that sets forth the grounds and evidence on which the petitioner believes the patent is invalid. The patent holder then has three months to file a preliminary response, arguing against the proposed invalidity grounds. Within three months, a three judge panel from the Patent Trial Appeal Board (PTAB) decides whether to institute the IPR and proceed with the trial phase. The panel proceeds to the trial phase if it finds that there is a “reasonable likelihood” that at least one of the patent claims being challenged is invalid. This is a lower burden of proof than that required in a district court litigation, where the burden of proof is “clear and convincing” evidence.

If the IPR is instituted and proceeds to the trial phase, the three judge panel must issue a final written decision twelve months from that date. Thus the entire IPR procedure takes no more than eighteen months. During the trial phase, the parties can take limited discovery, often in the form of deposing expert witnesses, and each side has the opportunity to submit a merits brief. There is usually an oral argument before the panel; however, live witness testimony is rarely included at this stage.

Through May 2016, over 3,000 IPRs had reached a final disposition. Trial was instituted in about half of those cases. Of those, about 1,000 of the cases reached a final written decision. All of the challenged claims were invalid in 70% of those cases and at least one claim was deemed invalid in another 14% of the decisions. Since the IPR process results in a high percentage of claims being invalidated, it is not surprising that many commentators consider the PTAB as the “patent death squad.”

In other words, the IPR procedure is friendly to patent challengers. It not only provides a relatively high probability of invalidating a patent, but also offers a quick decision (eighteen months from filing). This is especially useful for a company interested in bringing to market a product that may infringe a competitor’s patent. A quick decision on the patent’s validity generally will reduce costs as compared to traditional litigation and, importantly, will provide the company with greater certainty before expending resources on product development. Filing an IPR petition also may be useful for a company with has an established product that is facing litigation from non-practicing entities or other challengers. For that company, an IPR may be used to stop a costly patent challenge brought through traditional district court litigation.

Given the statistics, the patent holder’s best chance of prevailing is at the institution phase. Thus, for both challengers and patent holders alike, it is important to retain counsel that has the technical expertise of the patent subject matter, and who is experienced with the various rules and procedures of the IPR process.