Leveraging Ex Parte Reexamination for Patent Strategy

Ex parte reexamination has evolved into a primary strategic tool for patent portfolio management and competitive intelligence in the modern innovation economy. The procedure has experienced a dramatic resurgence, with filing requests more than doubling from 198 in 2020 to 425 in 2025. Given the universal standing and lower threshold for review, compared to other post-grant proceedings, and the strategic advantages reexamination offers over traditional litigation, it's no wonder the process has become an indispensable tool for many patent owners.

Who Can Initiate Reexamination?

Reexaminations provide universal standing under 35 U.S.C. § 302, which permits "any person" to file at any time during the patent's enforceability period, including expired patents still within the six-year damages window.

 The term “any person” includes:

• Accused infringers seeking to invalidate asserted patents

• Competitors targeting problematic patents in their field

• Patent owners are proactively strengthening their portfolios

• Investment entities conducting due diligence

• Anonymous third parties through counsel representation

The "any person" standard creates strategic flexibility unavailable in other post-grant proceedings, allowing parties to challenge patents without the timing restrictions or standing requirements that limit IPR and PGR proceedings. 

Substantial New Question Definition and Criteria

The procedure's foundation rests on establishing a "substantial new question of patentability" (SNQ) based exclusively on patents or printed publications. SNQ challenges are limited to novelty (§ 102) and obviousness (§ 103) grounds.

The SNQ standard, as detailed in MPEP § 2242, requires demonstrating a substantial likelihood that a reasonable examiner would consider the cited prior art important in determining patentability. The criteria for deciding SNQ emphasize that if the prior art would be regarded as necessary by a reasonable examiner, then SNQ should be found unless the same question has already been decided in a final holding of invalidity or previously addressed by the Office.

Examples That Satisfy SNQ Criteria Include:

• New technological teaching not previously considered during the original prosecution

• A materially new argument or interpretation of previously cited art

• Different application contexts where old art is considered for substantially different purposes

• Non-cumulative prior art that presents genuinely novel invalidity theories

The SNQ threshold establishes a deliberately low bar designed to strike a balance between protecting patent owners and preventing harassment while facilitating efficient validity review. The CAFC’s 2023 ruling, In re Cellect, further lowered the SNQ threshold. There, the CAFC affirmed that the absence of an explicit obviousness-type double-patenting analysis is sufficient to leave any questions the examiner “might” have considered available as “new” for SNQ. The court emphasized that SNQ determinations are factual and need only be supported by “substantial evidence,” a standard easily met when the written record is silent on the specific ground.

Determinations of no SNQ are final and non-appealable, making the quality of the initial request paramount. However, the 90-95% grant rate for SNQ determinations provides high confidence that filed requests will proceed to substantive examination.

The standard explicitly does not require a prima facie case of unpatentability, making it significantly easier to obtain reexamination than to prove invalidity in federal court. However, the "newness" requirement protects against harassment by preventing duplicate challenges based on identical grounds that the USPTO or federal courts have previously decided.

Procedural overview

The reexamination process unfolds in distinct phases designed to limit interaction between patent owners and challengers. Following submission, the USPTO Director has three months to determine whether the SNQ exists. While the statute assigns responsibility to "the Director," the  Central Reexamination Unit (CRU), a group of specialized examiners, actually conducts the three-month SNQ determinations.

If SNQ is determined, the limited interaction period allows patent owners to submit statements within two months, with challengers having an additional two months to reply. The reexamination proceedings continue until the CRU issues a final certificate outlining the status of the claims. The certificate represents the conclusive end point where appeal rights have been exhausted or waived. The issuance of the certificate itself isn't appealable, but the substantive decisions within the reexamination process are appealable by the patent owner. Crucially, patent owners must appeal any adverse decision within a nonextendable 63-day window.

The average duration of reexamination proceedings is 18.65 months. The patent owner can appeal adverse CRU decisions to the Patent Trial and Appeal Board (PTAB). The patent owner can further appeal adverse PTAB decisions to the Court of Appeals for the Federal Circuit (CAFC). Despite ex parte reexam appeals to the PTAB being handled with “special dispatch,” the time to receive a final decision increases to around three years if the patent owner chooses to appeal any adverse decision.

 The critical 63-day deadline to appeal the PTAB decision to the CAFC is established under 37 C.F.R. § 90.3(a)(1). The Federal Circuit cannot extend the time limit for appeal submissions and will "dismiss an appeal that is not filed within the statutory time limit". The 63-day period begins running from the "MAIL DATE" if the PTAB decision is provided by paper delivery, or the "NOTIFICATION DATE" if provided electronically. This calculation is strictly enforced, and the deadline includes the date of the Board's decision itself.

Outcomes—Historical Averages

Reexaminations have a 14.1% cancellation rate for all claims, which is significantly lower than the Inter Partes Review (IPR) rates of approximately 48%. The relatively low all kill rate still represents a substantial risk for patent owners and an opportunity for challengers. In 2023, nearly 65% of all reexaminations resulted in at least one claim amendment, which is consistent with historical averages. Patent owners should employ strategic amendment practices to limit the damage caused by claim cancellation.

These numbers indicate that challengers see at least some claim change (cancellation or amendment) in at least 65% of certificates, while patent owners only have a 22% of moving through reexamination with all claims unscathed. Understanding these outcomes is essential for effective strategic planning.

Strategic Applications in Technology Sectors

Offensive Deployment

For companies facing patent assertions, ex parte reexamination offers several advantages over alternative post-grant procedures. The lower cost compared to IPR or district court litigation makes it accessible for challenging patents where full-scale litigation might be economically prohibitive.

In semiconductor manufacturing disputes, where patent thickets are common, reexamination can systematically address multiple related patents. Challengers may challenge patents in coordinated waves, with successful invalidations creating precedential value for subsequent challenges within the same patent family. The procedure's accessibility to "any person" eliminates standing requirements that might complicate other challenges. This proves particularly valuable in competitive intelligence scenarios where companies may identify problematic patents before direct infringement allegations arise.

Defensive Utilization

Reexamination enables patent owners to defensively strengthen their patents in preparation for litigation. Rather than facing potentially hostile IPR or district court challenges, this approach enables controlled claim amendments under examination procedures. Additionally, AI companies can use defensive reexamination to add claims specifically targeting competitor implementations to strengthen enforcement positions. Crucially, the numbers suggest patent owners facing ex parte reexamination should expect to amend or lose claims unless prosecution histories are airtight.

Unlike IPR proceedings where no interviews are permitted, ex parte reexamination allows patent owners to conduct examiner interviews throughout the process, providing opportunities to educate examiners about the invention's technical merits and distinguish prior art. Early examiner interviews and thoughtfully crafted narrowing amendments remain the most effective tools for guiding key claims through the process.

Conclusion

Ex parte reexamination has emerged as a potent, cost-effective cancellation weapon. Whether wielded offensively to invalidate suspect claims or defensively to fortify one’s patents, mastery of its procedural nuances and statistical realities is now essential for IP counsel in fast-moving technology sectors.

Successful reexamination practice requires careful development of prior art and strategic presentation. The initial request must not only establish SNQ but also position the challenge for favorable examination. This demands a thorough understanding of prosecution history, claim construction principles, and examiner psychology. Patent owners facing reexamination should immediately assess amendment opportunities and develop comprehensive response strategies to address the challenges. The unique ability to conduct examiner interviews provides valuable intelligence about potential outcomes and amendment possibilities.

Sources:

1. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure § 2258 (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/s2258.html

2. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure ch. 30 (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/mpep-9015-appx-l.html#al_d1fbe2_1c35d_1e8

3. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure § 2209 (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/s2209.html

4. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure § 2210 (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/s2210.html

5. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure § 2242 (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/s2242.html#d0e225368

6. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure § 2272 (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/s2272.html

7. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure § 1214 (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/s1214.html

8. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure app. R (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/mpep-9020-appx-r.html#d0e330470

9. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure § 1.116 (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/mpep-9020-appx-r.html#d0e322826

10. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure app. L (10th ed. Rev. 10, June 2023), https://www.uspto.gov/web/offices/pac/mpep/mpep-9020-appx-.html#ar_d1d85b_16063_379

11. U.S. Patent & Trademark Office, Reexamination Operational Statistics (2023), https://www.uspto.gov/sites/default/files/documents/reexamination-op-stats.pdf

12. U.S. Patent & Trademark Office, Ex Parte Reexamination Filing Data, https://www.uspto.gov/dashboard/data/patents/ex-parte-filing-data.pdf