Imagine this. You were just served with a Complaint for patent infringement and learn that, some years ago, your competitor was granted a patent giving them a legal monopoly to exclude others, including you, from making, using, or selling a particular invention. Worse, after reviewing, you determine that your latest-and-greatest product is uncomfortably close to infringing the patent. Fortunately, you know that your competitor was not the first to develop that technology and that the Patent Office made a mistake in granting your competitor's patent. The day after receiving the Complaint, you dust off a 30-year-old textbook from college describing exactly what your competitor claims to have invented. You know you have the opportunity to invalidate the patent in the district court case, but you also know that process will be long and costly.1 Further, you know that it can be challenging to convince a lay jury that the Patent Office made a mistake—particularly under the heightened "clear and convincing" evidence standard in district court.
Do you have other options to make the wrongly issued patent—and corresponding lawsuit—go away? Today, by far the most popular alternative to litigation in this situation is inter partes review ("IPR").2 A decade ago, IPR was created as part of the America Invents Act ("AIA") to offer a faster, cheaper alternative to litigating validity in district court.3 It quickly became a favored tool for patent challengers–famously earning the "patent death squad" moniker.4 Recently however, guidance from the Patent Office suggests the Patent Trial Appeal Board ("PTAB"), created as part of the AIA in part to administer IPRs, will become more selective about which IPR cases it will agree to hear.5 The new guidance signals a move away from the more restrictive guidance of the Vidal Memorandum and back towards a broader application of the Fintiv factors, with the Director of the USPTO playing a more direct role in the initial discretionary denial assessment.6 These changes may push patent challengers who would otherwise favor IPRs to consider looking for other options. One existing (and significantly older) tool that may be a direct beneficiary is ex parte reexamination ("EPR"). This article briefly explains how an EPR works in comparison to an IPR and explores whether a potential shift is already underway.
A Primer on Ex Parte Reexamination as Tool for Patent Challengers Familiar with IPR:
Congress introduced ex parte reexamination as part of the Bayh-Dole Act in 1980, with it going into effect July 1, 1981.7 Chapter 2200 of the Manual of Patent Examining Procedure ("MPEP") is titled "Citation of Prior Art and Ex Parte Reexamination of Patents" and contains information relevant to EPRs.8 The following flow chart from the MPEP provides a general overview of the process:9
An EPR is an administrative procedure that allows the Patent Office to reconsider the patentability of one or more claims of an issued patent. Unlike an IPR, EPR is not an adversarial contest between two parties. Instead, it is fundamentally a second look by a patent examiner in light of prior art that raises "[a] substantial new question of patentability" about whether the patent should have been granted in the first place.10 Notably, this standard is significantly lower than the standard for instituting an IPR, which is a "reasonable likelihood that at least one of the claims challenged in the petition is unpatentable."11 The most recent data from the Patent Office indicates EPRs have an institution rate of 92.6%12 compared with, for IPRs, 74% for the most recent full year of data (2024) and 65% for the 2025 year-to-date data.13,14 This discrepancy is somewhat balanced by the fact that for instituted EPRs requested by a third-party, 18% result in all claims being cancelled as compared to 41% percent for IPRs which were instituted.15,16
Another difference between IPRs and EPRs is the initiation of the process. An EPR request can be filed by "any person" at any time during the enforceability of a patent, which includes the patent owner, an accused infringer, or even an anonymous third party.17 In contrast, only a non-owner of a patent, who has not previously challenged the patent in a civil action, and adheres to a one-year deadline if served with an infringement complaint may file an IPR.18 Additionally there is no option to file an IPR anonymously as the real parties in interest must be identified in the petition.19 Similar to an IPR, the request must identify prior art, limited to patents or printed publications, and explain how that art warrants institution with respect to at least one patent claim—noting the difference in the standards for institution discussed above.20
However, the biggest difference as compared to an IPR is what happens once the reexamination request is granted. The process shifts to being almost entirely and exclusively between the patent owner and the patent examiner. The requester's role is finished, with the exception of being able to file one reply if the patent owner submits a statement after the proceeding is instituted. The patent owner can then argue against the examiner's rejections and has a broad ability to amend the patent claims to overcome the cited prior art. This process resembles original patent prosecution, albeit with a more focused scope and a specialized examiner from the Central Reexamination Unit.21
Are EPRs Already Making Their Comeback?
Even before the recent IPR discretionary denial guidance from the Patent Office, the number of EPRs was already trending upward:22,23
This corresponds with a downward in the number of IPRs filed:24
A reasonable hypothesis is that the relationship between the filing of EPRs and IPRs is inverse—as less IPRs are filed, patent challengers are looking towards alternatives such as EPRs. EPR filing data for FY25 is not yet available from the Patent Office. However, year-to-date IPR filing data is available. Projecting IPR filings for FY25 based on the currently available data (and assuming a linear relationship) would indicate a further drop in IPR filings:25,26
Only time will tell, but based on these trends, it seems likely that EPRs will continue their quiet comeback—and potentially speed up due to the new guidance on discretionary denials for IPRs. Thus, as the IPR discretionary denial landscape continues to shift, patent challengers should familiarize themselves with this older, but nevertheless powerful, tool.
Footnotes
1. For example, according to Docket Navigator, the national average time to trial for patent cases is 37 months.
2. During fiscal year 2024, there were 1,250 IPRs filed, 38 Post Grant Reviews filed ("PGRs"), and 425 ex parte reexaminations ("EPRs") filed. See U.S. PAT. & TRADEMARK OFF., Patent Trial and Appeal Board (PTAB) performance benchmarks for dispositions, pendency, inventory, and other tracking measures, FY24 Q4 Outcome Roundup, https://www.uspto.gov/sites/default/files/documents/ptab_aia_fy2024__roundup.pdf (last accessed 7/14/2025) (showing IPR and PGR statistics); U.S. PAT. & TRADEMARK OFF., Reexamination Statistics, https://www.uspto.gov/sites/default/files/documents/ex_parte_historical_stats_.pdf (last accessed 7/14/2025) (showing EPR statistics).
3. While, IPRs are generally faster, there is conflicting evidence as to whether they are indeed cheaper. See AIPLA, Report of the Economic Survey (2019), https://ipwatchdog.com/wp-content/uploads/2021/08/AIPLA-Report-of-the-Economic-Survey-Relevant-Excerpts.pdf (last accessed 7/14/2025) (showing that roughly 70% of responders believed the cost of filing a post-grant proceeding to be about the same as defending a litigation).
4. This term was coined by former Federal Circuit Chief Judge Randall Rader in 2013. See Rob Sterne & Gene Quinn, PTAB Death Squads: Are All Commercially Viable Patents Invalid?, https://ipwatchdog.com/2014/03/24/ptab-death-squads-are-all-commercially-viable-patents-invalid/id=48642/ (last accessed 7/14/2025).
5. In February 2025, the USPTO rescinded former Director Kathi Vidal's Interim Procedure for Discretionary Denials Memorandum, followed by Chief Administrative Patent Judge Scott Boalick's guidance on the rescission, and Acting Director Coke Morgan Stewart's interim memorandum on PTAB Workload Management.
6. A more in-depth analysis of these changes was previously explored in the Baker Botts' IP Report article titled Discretionary Denials at the PTAB: Strategic Insights for Petitioners and Patent Owners in a Shifting Landscape by Jennifer Robichaux Carter and Zacharias Shepard available at https://www.bakerbotts.com/thought-leadership/publications/2025/july/discretionary-denials-at-the-ptab.
7. See Pub. L. No. 96-517, 94 Stat. 3015 (1980).
8. MANUAL OF PATENT EXAMINING PROCEDURE § 2200 (9th ed., rev. 01.2024, Nov. 2024).
9. Id. at § 2201.
10. Id.
[11] 37 CFR § 42.108(c).
12. U.S. PAT. & TRADEMARK OFF., Ex Parte Reexamination Filing Data, (Sept. 30, 2024), https://www.uspto.gov/sites/default/files/documents/ex_parte_historical_stats_.pdf.
13. U.S. PAT. & TRADEMARK OFF., Patent Trial and Appeal Board (PTAB) performance benchmarks for dispositions, pendency, inventory, and other tracking measures, (May 2025), https://www.uspto.gov/sites/default/files/documents/ptabaia20250531.pdf.
14. This drop-off is likely due to the changes in discretionary denial policy discussed above.
15. U.S. PAT. & TRADEMARK OFF., Ex Parte Reexamination Filing Data, (Sept. 30, 2024), https://www.uspto.gov/sites/default/files/documents/ex_parte_historical_stats_.pdf; U.S. PAT. & TRADEMARK OFF., Patent Trial and Appeal Board (PTAB) performance benchmarks for dispositions, pendency, inventory, and other tracking measures FY24 Q4 Outcome Roundup, https://www.uspto.gov/sites/default/files/documents/ptab_aia_fy2024__roundup.pdf.
16. These numbers are somewhat hard to compare given that EPRs cannot be "settled" in the same way an IPR can and because EPRs often result in the claims be changed rather than cancelled
17. See MPEP § 2209.
18. See 35 U.S. Code § 311; 35 U.S. Code § 315.
19. See 35 U.S. Code § 312.
20. See 35 U.S. Code § 311.
21. A note of caution: A patent owner can use the reexamination process to their advantage, not only defending the original claims but also crafting new, amended claims that are narrower, stronger, and specifically designed to cover the requester's product or service. A requester could thus face a reexamined patent that is more difficult to invalidate than the original after it emerges from EPR.
22. U.S. PAT. & TRADEMARK OFF., Ex Parte Reexamination Filing Data, (Sept. 30, 2024), https://www.uspto.gov/sites/default/files/documents/ex_parte_historical_stats_.pdf.
23. Note that, the drop off shown in 2013 corresponds with the introduction of IPRs with the AIA on March 16, 2013.
24. U.S. PAT. & TRADEMARK OFF., Patent Trial and Appeal Board (PTAB) performance benchmarks for dispositions, pendency, inventory, and other tracking measures, https://www.uspto.gov/patents/ptab/statistics.
25. Notably, the discretionary denial guidance was only known for a portion of the FY25 period.
26. U.S. PAT. & TRADEMARK OFF., Patent Trial and Appeal Board (PTAB) performance benchmarks for dispositions, pendency, inventory, and other tracking measures, https://www.uspto.gov/patents/ptab/statistics.
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