The United States Patent and Trademark Office (USPTO) has published a proposed rule requiring every third-party request for ex parte patent reexamination to identify the requester and all other real parties in interest. The identifying statement could remain confidential from the public upon request, but the USPTO itself would receive the information to evaluate statutory estoppel, false certifications, misrepresentations, and fraud.

Comments are due August 21, 2026. This is a proposed rule — it is not yet a final requirement and will not take effect until the USPTO publishes a final rule following the comment period.

Ex parte reexamination is a USPTO procedure that allows any person — including a competitor, a potential infringer, or a litigation funder — to request that the USPTO reexamine an issued patent based on prior art (patents or printed publications) that raises a substantial new question of patentability. Unlike inter partes review (IPR) and post-grant review (PGR), which are adversarial proceedings before the Patent Trial and Appeal Board (PTAB), ex parte reexamination is conducted primarily between the patent owner and the USPTO examiner, with limited participation by the requester after the initial filing.

The anonymity problem. Under current rules, a third-party requester in ex parte reexamination is not required to identify itself or disclose who is funding or directing the challenge. This anonymity has been used by competitors, litigation funders, and other parties to challenge patents without revealing their identity or their relationship to ongoing litigation. The anonymity creates several problems:

• Statutory estoppel evasion. A party that has already participated in an IPR or PGR proceeding may be subject to statutory estoppel — a bar on raising in subsequent proceedings the same grounds that were or could have been raised in the IPR or PGR. Anonymous ex parte reexamination requests can be used to circumvent this estoppel by concealing the identity of the real party in interest.
• False certifications. Requesters are required to certify that the reexamination request complies with applicable rules. Anonymous requests make it difficult for the USPTO to verify the accuracy of these certifications.
• Coordinated challenges. Multiple anonymous requests can be filed by related parties to coordinate a sustained challenge to a patent without revealing the coordination.

Under the proposed rule, every third-party ex parte reexamination request must include a statement identifying:

1. The requester — the person or entity filing the request
2. All real parties in interest — any person or entity that has a financial interest in the outcome of the reexamination, including:
   • Entities that are funding or directing the challenge
   • Entities that have indemnification obligations related to the patent
   • Entities that have a contractual right to control the challenge
   • Litigation funders with a financial stake in the outcome

Confidentiality. The identifying statement can be designated as confidential — meaning it would not be publicly available in the patent file. However, the USPTO would have access to the information for internal purposes, including evaluating estoppel, certifications, and potential fraud.

Ongoing disclosure obligation. The proposed rule would also require requesters to update the disclosure if the identity of real parties in interest changes during the reexamination proceeding.

The primary driver of the proposed rule is the statutory estoppel problem. Under 35 U.S.C. § 315(e) and § 325(e), a petitioner in an IPR or PGR proceeding is estopped from asserting in subsequent proceedings — including district court litigation and ITC proceedings — any ground that the petitioner raised or reasonably could have raised in the IPR or PGR.

The estoppel applies to the petitioner and its real parties in interest and privies. If a party that is estopped from raising certain grounds in litigation files an anonymous ex parte reexamination request raising those same grounds, the anonymity conceals the estoppel violation. The proposed rule would allow the USPTO to identify and address these situations.

Practice note: Companies that have participated in IPR or PGR proceedings — as petitioners or as real parties in interest — should carefully evaluate whether any ex parte reexamination requests they are considering would raise grounds that were or could have been raised in the prior proceedings. The proposed rule would make it significantly more difficult to use anonymous ex parte reexamination to circumvent estoppel.

The proposed rule has significant implications for litigation funders — third-party investors that finance patent challenges in exchange for a share of the proceeds. Litigation funders have become major participants in U.S. patent litigation and patent challenge proceedings, and many have used anonymous ex parte reexamination requests to challenge patents in which they have a financial interest.

Under the proposed rule, litigation funders with a financial stake in the outcome of a reexamination would be required to be identified as real parties in interest. This disclosure requirement — even if confidential from the public — would allow the USPTO to evaluate whether the funder's involvement creates estoppel issues or other compliance concerns.

Practice note: Litigation funding agreements for patent challenges should be reviewed to assess disclosure obligations under the proposed rule. Agreements that give funders control over the challenge strategy — including the right to direct which grounds are raised — are more likely to make the funder a real party in interest. Agreements should include provisions addressing the parties' obligations under the proposed disclosure requirement.

For patent owners, the proposed rule provides a significant benefit: the ability to identify the real parties behind reexamination challenges and assess whether those parties are subject to estoppel or other limitations. Patent owners who receive ex parte reexamination requests should:

• Request access to the real-party-in-interest disclosure (if the rule is finalized)
• Evaluate whether the identified parties are subject to statutory estoppel based on prior IPR, PGR, or litigation proceedings
• Consider whether the disclosure reveals coordinated challenges by related parties that could be addressed through consolidation or other procedural mechanisms

The proposed rule has direct relevance for Turkish companies that hold U.S. patents or that are involved in U.S. patent disputes:

Patent owners. Turkish companies with U.S. patents that are subject to ex parte reexamination challenges will benefit from the proposed rule's disclosure requirement, which will allow them to identify the real parties behind challenges and assess estoppel arguments.

Patent challengers. Turkish companies that are challenging U.S. patents — whether through ex parte reexamination, IPR, or PGR — should review their challenge strategies in light of the proposed rule. If the rule is finalized, anonymous ex parte reexamination will no longer be available as a tool for circumventing estoppel or concealing coordinated challenges.

Licensing and M&A. Turkish companies acquiring U.S. companies or licensing U.S. patents should conduct due diligence on pending reexamination requests and the identity of real parties in interest, as these may affect the validity and enforceability of the patents being acquired or licensed.

ULF New York advises Turkish companies and investors on U.S. patent strategy, PTAB proceedings, patent licensing, and intellectual property due diligence in cross-border transactions.