Insights

Ex parte reexamination is seeing a resurgence in popularity as a cost-effective means to challenge a patent’s validity and should be part of your patent strategy. An ex parte reexamination is a proceeding in which any party — including a patent owner or an anonymous third party — may submit prior art to request that the United States Patent and Trademark Office (USPTO) reassess an issued patent's validity. Once overshadowed by the introduction of inter partes review (IPR) and post-grant review (PGR) following the enactment of the America Invents Act in 2012, ex parte reexamination is now experiencing a significant resurgence as a strategic alternative to both proceedings. This client alert explains what is driving ex parte reexamination’s resurgence and what it means for your patent strategy.

Applicants entering the U.S. national phase of an international (PCT) application have two options: enter the national stage under 35 U.S.C. §371 or file a “bypass” national application under 35 U.S.C. § 111(a). A bypass application allows applicants to file a new U.S. application that claims priority to the PCT application, treating the PCT application as a U.S. parent and bypassing the traditional national phase entry. Depending on the applicant’s goals and strategy, bypass applications can be filed as a continuation, divisional, or continuation-in-part (CIP).

On March 13, 2025, the United States Court of Appeals for the Federal Circuit issued a decision about Patent Term Extensions (PTEs) under the Hatch-Waxman Act for reissue patents. In Merck Sharp & Dohme B.V. v. Aurobindo Pharma USA, Inc. (No. 2023-2254), the Court confirmed that the PTE provision under 35 U.S.C. § 156 refers to the original patent’s issue date, not the reissue patent’s issue date. Thus, the issue date of the original patent should be used when calculating the extension period.