Year in Review: How Ex Parte Reexamination Eclipsed IPR in 2025

2025 will close with the largest single-year increase in ex parte utility-patent reexamination filings since the AIA transition. Through the first eleven months, calendar-year filings have already exceeded any annual total in the previous five years. The trajectory is consistent: each quarter has run at or above the previous quarter, with Q3 hitting a quarterly high not seen in over a decade. This is a year-end retrospective on a procedure that moved from background option to primary invalidity vehicle in twelve months.

All filing and outcome counts in this retrospective cover utility-patent ex parte reexaminations. Design and reissue reexams are tracked separately.

The volume story

Annual ex parte reexamination filings, 2020-2025:

• 2020: 198 filings
• 2021: 299 filings
• 2022: 299 filings
• 2023: 316 filings
• 2024: 330 filings
• 2025 (Jan-Nov): well above 500 filings, on pace toward 600

The 2020-2024 range was 198-330, a 132-filing band. 2025 will close roughly 270 filings above 2024. That is more than the entire range of the prior five years combined.

The driver is widely understood. On February 28, 2025, USPTO Acting Director Stewart rescinded the June 2022 Vidal Fintiv memo that had treated Sotera Stipulations as foreclosing discretionary IPR denial. A follow-on Stewart interim guidance memo issued March 26, 2025 clarified the new approach. The procedural reset shifted the cost-benefit calculation for parallel-track invalidity practice. Petitioners who would have filed IPRs through 2024 became reexam requesters through 2025.

Quarterly cadence

Filing pace accelerated through the year:

• Q1: above 2024 baseline, with the final weeks of the quarter capturing the immediate post-Sotera bump.
• Q2: first full quarter of the post-rescission environment. Filings ran materially above 2024's quarterly pace.
• Q3: Unified Patents reported 198 filings in Q3 alone, a single quarter that matched the entire 2020 calendar year and represented a quarterly high since the modern era of the procedure began.
• Q4 (through November): pace consistent with Q3.

The Q1-to-Q3 ramp aligned precisely with the late-February Vidal-memo rescission and the March follow-on guidance. The Q3-to-Q4 stability suggests the new equilibrium is settling, not still climbing.

Who is filing

Third-party requesters drove the surge. Through November, third-party filings accounted for the overwhelming majority of new requests, well above the historical third-party share. Patent owner filings tracked the prior baseline almost exactly.

The composition signals that the diversion is migrating from a specific population: parallel-track defendants in district court litigation, frequent IPR petitioners, and challengers whose prior art profile was always more reexam-shaped than PTAB-shaped. The surge is concentrated, not diffuse.

Why reexam took the share

Three structural reasons sit underneath the volume:

First, no estoppel. 35 U.S.C. 315(e) IPR estoppel bars subsequent assertion of the same grounds. Ex parte reexam carries no analogous bar. (Estoppel in ex parte reexam, in detail.) For a challenger building parallel invalidity exposure across district court and the USPTO, that asymmetry favors the procedure that does not lock in a downstream position.

Second, lower cost. Reexam typical legal fees ($50K-$150K) sit well below typical IPR fees ($300K-$600K+). The cost advantage was always there. It became more compelling when the IPR upside became less certain.

Third, a more predictable gate. Reexam SNQ grant rates have run roughly 95% across closed cases. IPR institution rates ran near 68% by petition in FY2024. Post-rescission, they have come under additional pressure. A challenger faces structurally lower gate-denial risk in reexam.

What didn't change

Three things held constant through 2025:

• The reexam procedural sequence. The SNQ determination, patent owner statement, office action cycle, and certificate issuance all worked as they have for years.
• The cert rate. Closed reexams continue to issue certificates in approximately 94% of cases.
• The examiner pool. Roughly 110 active reexam examiners continued to absorb the rising caseload. No structural USPTO staffing change was announced during the year.

The volume scaled. The procedure absorbed it.

What to watch in 2026

Three storylines will define the coming year:

First, whether the volume holds. The 2025 surge was driven by a specific procedural reset. The new equilibrium has not yet been tested by a calendar of stable PTAB practice. If discretionary denial doctrine continues to favor patent owners through 2026, the diversion sustains. If the PTAB pulls back, some volume returns to IPR.

Second, whether the 5% SNQ denial rate holds. The 2025 cohort brought a wider, less reexam-experienced population of requesters to the procedure. Whether examiners hold the denial line at 5%, or whether the SNQ gate tightens against weaker requests, is the central data question.

Third, whether the USPTO acts. The reexam procedure has been operationally consistent for over four decades. Procedural review at the USPTO is always possible, particularly with the volume now visible. Any change in how the SNQ stage operates could materially reshape the procedure's strategic position.

A reversal of an era

For roughly a decade after the AIA, IPR was the default. Ex parte reexam was the fallback for pre-AIA patents, niche tactical plays, and budget-constrained challengers. 2025 reversed that. Reexam is now the larger-volume procedure for the contested patents that matter. Whether that holds through 2026 is the central procedural question of the year ahead.