2025 Summer Associate Alexis Hardy contributed to this article.
Introduction
Obvious-type double patenting (ODP) has historically served as a tool to prevent patent owners from extending exclusivity beyond the statutory allowed patent term and to tie patent families together during sale. Historically, when ODP is asserted a patent owner can use a terminal disclaimer to overcome the ODP rejection. A terminal disclaimer is a way for a patent owner to link the life of a second later filed patent to the first filed patent, and ultimately disclaims a portion of the later-filed patent’s term to the first filed patent.
Once a patent expires there is no longer an option for the patent owners to file a terminal disclaimer to overcome the ODP rejection. For example, there is a rise in ex parte reexamination’s with substantial new questions (SNQs) and rejections based on ODP following an infringement verdict coupled with a missed or failed inter partes review (IPR). And unless the patent owner can win on patentably distinct claim arguments, they may lose their patents for further enforcement. Members of the patent bar have argued that this stance of the courts and the United States Patent and Trademark Office (USPTO) is inequitable and unfair.
On the other hand, members of the bar have also argued this is a valid opportunity for accused infringers to avoid paying damages by triggering reexamination after litigation and using ODP as a late-stage attack.
This article explores doctrinal history, fairness issues, and policy arguments that patent owners and requesters need to understand how to navigate ODP in reexamination.
Doctrinal Foundation: What is ODP, Why Does it Exist, and Why are Terminal Disclaimers Ineffective for Expired Patents
ODP is a judicial doctrine that was designed to prevent a patent owner from securing multiple patents with non-identical but non-patentably distinct, e.g., obviously identical, claim scope. ODP is different from statutory double patenting, which bars two patents on the exact same invention under 35 U.S.C. §101, because ODP concerns claims that are different but obvious variations. While statutory double patenting cannot be cured, ODP can usually be resolved during prosecution by filing a terminal disclaimer. Filing a terminal disclaimer under 37 C.F.R. § 1.321 aligns the expiration date of the later patent with the earlier one and requires common ownership to ensure no unjustified term extension occurs.
Yet once a patent expires, a terminal disclaimer can no longer be used to cure the ODP rejection. For example, the inability to overcome an ODP rejection with a terminal disclaimer was upheld by the Federal Circuit in In re Fallaux, 564 F.3d 1313 (Fed. Cir. 2009). This creates serious problems for a patent owner when ODP is raised after patent expiration, particularly in ex parte reexamination. Post-expiration, a patent owner cannot amend claims or disclaim any remaining term, effectively leaving them with no way to cure the defect if the USPTO does not agree with their patentably distinct arguments.
Critical Issues for Patent Owners and Patent Challengers to Consider for ODP Rejections of Expired Patents in Reexamination
The bar is seeing this being utilized by patent challengers/infringers in a situation where an IPR was denied or all infringed claims were found non unpatentable in a Final Written Decision. In these situations, the challengers/infringers have started using this process to avoid paying damages. In some situations, the challengers/infringers can go back to court and try to unwind the judgment or avoid payment altogether.
Patent owners have done their best to push back against this Catch-22 situation arguing it violates basic fairness and potentially Supreme Court doctrine. The authors have seen arguments in exemplary reexaminations arguing the following points:
- Preclusion: If the patent was already upheld in court or damages were awarded, patent owners have argued that the ODP issue should have been raised earlier and is barred by claim preclusion or issue preclusion.
- Challenge the SNQ: ODP is not based on new prior art as the original Examiner had the opportunity to make the rejection and did not, so patent owners have argued that it does not meet the “substantial new question of patentability” standard required for reexam under 35 U.S.C. § 303. See In re Cellect, LLC, 81 F.4th 1216 (Fed. Cir. 2023).
- Petition to dismiss: Patent owners have filed a 37 C.F.R. §§ 1.181/182/183 petition asking the USPTO to terminate the reexamination because no terminal disclaimer can be filed and the SNQ is improper and inequitable.
- Public rights and constitutional challenge: Under Oil States Energy Services, LLC v. Greene’s Energy Group, LLC, 138 S.Ct. 1365 (2018), patent owners have argued that expired patents fall outside the USPTO’s jurisdiction for handling private rights versus public rights and that reexamination violates due process.
- Stay the reexamination: If there is parallel litigation, patent owners have argued that the USPTO should stay the reexamination to prevent inconsistent outcomes or procedural abuse until the litigation is completed through exhausting all appeals.
Unfortunately, patent owner tools are limited and not guaranteed to succeed, but they provide a starting point for rebutting ODP SNQs and rejections in reexaminations.
Takeaways
Patent owners and patent challengers need to be aware of the strengths and weaknesses of arguments that can be raised in ex parte reexaminations for expired patents, including the use of ODP. The courts, USPTO, and practitioners have debated whether this practice exploits a procedural gap that gives patent owners no way to respond and whether that raises serious questions about fairness, statutory authority, and constitutional limits on USPTO power. Courts, policymakers, and the USPTO should take steps to clarify this issue.
