Reexamination and Central Reexamination Unit – By the Numbers 2025 (Including Reflections on Related PTAB and District Court Proceedings)

Senior Manager of Business Development and Analytics, Patrick Murray, contributed to this article. 

As we continue to follow the changes to AIA proceedings at the Patent Trial and Appeal Board (PTAB), we are also tracking the evolution of post-grant challenge strategy at the Central Reexamination Unit (CRU).

First, we have been tracking reexamination request filings, and the trend is quite accelerated for 2025 compared to previous years and quarter-over-quarter in 2025.

Most telling is comparing inter partes review and post-grant review petition filings, and reexamination request filings over the past seven years, with a dramatic crossing of reexamination requests over AIA petitions in the last two months.

To understand the motivations behind filing increased numbers of reexam requests in previous years, we compared the history of the reexam-requested patent in terms of past PTAB-challenge status at the time of reexam request filing. These comparisons show that the increase in reexam requests are primarily driven by requestors choosing to challenge patents at the CRU as a first strategy, rather than using the CRU as a “second bite at the apple,” as was increasingly common in the 2019-2021 timeframe.

Finally, district court data pulled from Docket Navigator show that requests for stays pending reexams have been more frequently successful in 2024 and 2025. This reversed a trend towards denial of such requests observed from 2020-2023.

District Court Stays Pending Reexamination

We will revisit in 2026 to see if these trends continue as the new PTAB rules and procedures take full effect.