For years, parallel proceedings at the Patent Trial and Appeal Board (PTAB) were the near-automatic response of a defendant in district court patent litigation. Accused infringers routinely filed petitions—especially inter partes review (IPR) petitions—challenging validity of the asserted patents at the PTAB. Given the PTAB’s technical expertise, historically favorable invalidation rates, and lower standard of review on invalidity, this has been a favored approach among defendants.

Today, that reflexive approach warrants reconsideration. Recent developments at the PTAB have prompted both patent owners and accused infringers to reassess whether parallel proceedings at the PTAB remains the default, or whether sticking to district court is the more viable option.

A More Uncertain PTAB Landscape

As we have covered in prior blog posts, one of the biggest changes at the PTAB has been the new discretionary denial process. Previously, petitioners were mainly concerned with filing their petitions within a 1-year statutory window, but now petitioners face broader timing considerations, including how long the challenged patent has been in force. PTAB 2025 statistics indicate 60% of petitions were denied for discretionary considerations. Given the high cost of filing a PTAB challenge, petitioners may be reconsidering their strategy to waste the expense and burden of putting together a PTAB challenge that may be denied on its face before the merits are even considered.

Institution rates likewise declined in 2025. Thus, the previous benefits of a PTAB challenge (enhanced technical expertise and a lower standard of review) are not necessarily being realized. Where a petition does survive the institution phase, there is less than a 50% chance that the instituted claims will be found unpatentable at final written decision. In that case, petitioner will be estopped from asserting the same arguments in district court that it raised, or could have raised, at the PTAB, which could significantly weaken a defendant’s case.

Uptick in Requests for Reexamination

Along with these PTAB changes has come a sharp increase in ex parte requests for reexamination. In 2025, the Patent Office reported the highest number of reexamination requests filed since the availability of IPRs at 491. The Patent Office has also reported 236 reexamination requests filed in the first quarter of 2026 alone. The data suggests that practitioners have turned to reexamination requests as an alternative to filing petitions (e.g., inter partes review or post-grant review petitions) at the PTAB. Because ex parte reexaminations operate under a different standard of granting review and are not subject to the same discretionary denial process, practitioners may view this as a more attractive approach to challenging patent validity in a parallel proceeding.

District Courts Regain Strategic Weight

Patent practitioners expect to see a shift back towards patent litigation disputes being decided exclusively in district courts. With the exception of certain jurisdictions (e.g., the Eastern District of Texas), many district courts have demonstrated a willingness to stay the litigation pending resolution of any PTAB proceedings. This previously provided a strategic advantage for defendants who could have their invalidity case heard first at the PTAB before having to defend against infringement in district court.

Given the latest shifts in PTAB policy and a sharp increase in discretionary denials, however, defendants may decide to increasingly forego filing parallel PTAB proceedings. Patent owners, for their part, have already begun adapting to this new landscape by accelerating case schedules, resisting stays, and arguing against discretionary denials. Patent owners’ efforts accompanied by the high cost of PTAB filings, diminished likelihood of institution, and estoppel risk, may spur defendants to choose to confine the litigation to the district court only.

Parallel PTAB and district court proceedings are no longer assumed to be a streamlined, complementary path. Both plaintiffs and defendants are forced to make early strategic decisions regarding parallel PTAB proceedings. Plaintiffs asserting older patents or patents where defendants were put on notice far in advance may feel more confident in bringing lawsuits in most district courts as the chances of a discretionary denial at the PTAB are increased. On the other hand, when asserting newer patents, plaintiffs may revert to venue shopping for districts that have fast trial schedules and are unlikely to grant a stay because the PTAB has shown a willingness to discretionarily deny petitions where the district court will reach trial before the PTAB. Defendants who see the PTAB as the best option for invalidating a patent, however, should consider filing PTAB petitions even before being sued in district court to give themselves the best chance of avoiding discretionary denial.

The Proskauer Team is continuing to monitor the evolving guidance and outcomes of PTAB proceedings relating to discretionary denials and institutions. We are happy to discuss any questions you may have regarding how these developments may affect your IPR and district court litigation strategy.

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Photo of Erik Milch Erik Milch

Erik Milch is a partner in the Litigation Department and a member of the Intellectual Property, Patent Law and Trials group.

Erik brings more than 20 years of experience litigating in key jurisdictions across the U.S., as well as before the International Trade…

Erik Milch is a partner in the Litigation Department and a member of the Intellectual Property, Patent Law and Trials group.

Erik brings more than 20 years of experience litigating in key jurisdictions across the U.S., as well as before the International Trade Commission and the U.S. Patent and Trademark Office. As a first-chair trial lawyer, Erik litigates complex matters involving medical devices, life sciences instrumentation, pharmaceuticals, electrical and computer technology, and consumer products. He regularly counsels clients in a range of industries in connection with patent procurement, development of patent portfolios, patent licensing, valuation of patent portfolios in business transactions and transactional diligence.

Erik has extensive experience in all aspects of patent litigation from pre-filing through appeal, including enforcement of patents against competitors and defense of patent infringement allegations. His technical background includes microfluidics, lab automation, optical imaging instruments, wound closure, surgical instrumentation, orthopedics, autoinjectors, tissue resection and sealing, pharmaceuticals, haptic feedback systems, computer software, consumer products, fluid mechanics applications, automotive engines and mechanical and electrical components, aerospace propulsion and control systems, weapons systems, and telecommunications.

Erik has been consistently recognized in Chambers USA and IAM Patent 1000 for his significant expertise in patent litigation. He was also recognized as a “Top Lawyer” by The Washingtonian.

Prior to pursuing a legal career, Erik earned a bachelor’s degree in mechanical engineering from Georgia Tech, where he developed a deep appreciation for cutting-edge technology and its potential to drive progress. His background in engineering equips him with a unique ability to comprehend intricate technical concepts. This enables him to effectively navigate the intricate world of patent litigation, combining his legal skills with technical know-how to provide comprehensive and strategic counsel to his clients.

In addition to his academic accomplishments, Erik served as an officer in the United States Navy. His military background instilled in him a strong sense of discipline, leadership, perseverance, and attention to detail; qualities that continue to guide him in his legal practice.

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Photo of Elizabeth Shrieves Elizabeth Shrieves

Elizabeth (Beth) Shrieves is an associate in the Litigation Department and a member of the Intellectual Property and Patent Law groups. Beth has experience litigating in numerous federal district courts across the United States, as well as before the Federal Circuit, U.S. Patent…

Elizabeth (Beth) Shrieves is an associate in the Litigation Department and a member of the Intellectual Property and Patent Law groups. Beth has experience litigating in numerous federal district courts across the United States, as well as before the Federal Circuit, U.S. Patent and Trademark Office, and International Trade Commission. Beth’s experience covers a wide variety of products and technology involving software and applications, medical devices and technology, electrical hardware, telecommunications, supercapacitors, automotive engines, weapon systems, and consumer products. She has counseled clients throughout all stages of litigation, including both plaintiff and defense work, from pre-suit investigation, initial pleadings, discovery, trial, and through appeal.

Beth graduated from George Mason University School of Law where she earned her J.D., Magna Cum Laude. Prior to earning her law degree, she received a bachelor’s degree from Wake Forest University where she also graduated Magna Cum Laude. Beth also previously worked as a paralegal where she gained a deeper understanding of the nuances of commercial litigation.

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