Is Ex Parte Reexamination Making a Comeback?

In recent years, inter partes review, or IPR, has been the best-known Patent Office procedure for challenging issued patent claims. Now, recent developments at the USPTO have made ex parte reexamination worth a closer look.

Why the renewed interest?

The Patent Office has recently changed how it handles discretionary denial issues in IPR and post-grant review proceedings. In 2025, the USPTO announced an interim process that separates discretionary-denial issues from the merits of the petition, and the USPTO’s published materials describe page limits and briefing procedures for those issues.

That matters because a petitioner can spend substantial time and money preparing an IPR petition and still face a threshold fight over whether the PTAB should institute review at all. Parallel district court litigation, timing, prior challenges, real-party-in-interest issues, and other discretionary considerations can become important before the Board ever reaches the merits.

By contrast, ex parte reexamination is a different animal. It is based on patents and printed publications that raise a substantial new question of patentability. Once reexamination is ordered, the proceeding is conducted between the patent owner and the Patent Office, not as a full adversarial contest between the patent owner and the requester. The USPTO’s rules give a third-party requester only a limited role after filing; for example, the requester may reply if the patent owner files a statement, but if the patent owner does not file that statement, no further requester submission is considered at that stage.

The advantages of reexamination

For an accused infringer or other third-party challenger, ex parte reexamination may offer several practical advantages.

First, it can be less procedurally complex than IPR. The requester does not have to litigate a trial-like proceeding before the PTAB. There are no depositions, expert declarations may be less central, and the filing can be more focused on prior art patents and printed publications.

Second, reexamination is not subject to the same one-year litigation bar that applies to IPR after service of a complaint. That can make it useful where a defendant missed the IPR deadline or where the timing of the dispute makes IPR unattractive.

Third, ex parte reexamination does not carry the same estoppel consequences as IPR. That can matter significantly where a party wants to challenge patentability in the Patent Office but preserve flexibility in district court.

Fourth, the requester may be able to remain less visible than in a fully adversarial PTAB proceeding, depending on how the request is filed and the strategic posture of the dispute.

Those advantages explain why ex parte reexamination is getting renewed attention. Reuters recently reported that challengers have increasingly turned to reexamination amid changes in PTAB institution practice, while also noting the important tradeoff: after reexamination is instituted, the requester largely loses control over the proceeding.

The disadvantages are real

Reexamination is not a substitute for IPR in every case. The most important drawback is control. In IPR, the petitioner participates throughout the proceeding. In ex parte reexamination, once the Patent Office grants the request, the matter largely proceeds between the examiner and the patent owner. The requester receives copies of Office actions and patent owner responses, but does not get the same adversarial role it would have in IPR.

That can be frustrating if the patent owner makes arguments or amendments that the requester believes are wrong or incomplete. The requester may monitor the proceeding, but it does not control the examiner’s analysis or get the same opportunity to respond that it would have before the PTAB.

Also, reexamination can take time. IPR has a statutory structure designed to move toward a final written decision on a defined schedule. Reexamination is handled through examination channels and may not provide the same timing certainty.

Sometimes the revised scope will be narrower. Ex parte reexamination is generally built around patents and printed publications. It is not the right vehicle for every invalidity theory. If the best arguments involve public use, on-sale activity, lack of enablement, inventorship, or other issues outside the printed-publication prior-art framework, reexamination may be incomplete or unavailable as the principal attack.

Patent owners can amend claims during reexamination. That can be useful if the goal is to narrow the patent to avoid infringement, but dangerous if the patent owner emerges with amended claims that are harder to challenge or easier to assert against redesigned products.

Patent owners should adjust too

This is not only a challenger-side issue. Patent owners should assume that ex parte reexamination may be used more frequently, including in parallel with litigation or after an IPR strategy becomes unavailable.

That means patent owners should be ready to respond quickly to reexamination requests, especially where important patent claims are involved. Recent commentary has also noted a new USPTO option for patent owners to file a pre-order submission before the Office decides whether to grant reexamination, which could give patent owners an earlier opportunity to address whether the request truly raises a substantial new question of patentability.

For patent owners, the response strategy should not be purely technical. A reexamination response can affect litigation positions, claim construction, damages theories, continuation strategy, competitor design-arounds, and future licensing value. Amendments may solve one problem while creating another.

When reexamination may make sense

Ex parte reexamination may be worth considering when:

• A strong printed-publication prior-art challenge exists.

• The IPR deadline has passed or discretionary denial risk is high.

• The challenger wants a lower-cost Patent Office challenge.

• The challenger wants to avoid IPR estoppel.

• The goal is to narrow or weaken the patent, even if full cancellation is uncertain.

• The dispute is not yet in litigation, but the patent presents a business risk.

By contrast, IPR may remain the better vehicle where the challenger needs active participation, expert-driven argument, a more predictable schedule, or a final written decision with stronger immediate litigation implications.

The practical takeaway

The practical lesson is not that reexamination has replaced IPR. It has not. The better lesson is that post-grant patent strategy is becoming more forum-specific. A challenger should not reflexively file an IPR just because that has been the standard playbook. A patent owner should not assume that avoiding IPR institution risk ends the Patent Office threat.

For both sides, the right question is more basic: What is the objective? Cancel the claims? Narrow them? Create settlement leverage? Stay district court litigation? Preserve invalidity defenses? Avoid estoppel? Increase licensing pressure? Reduce freedom-to-operate risk?

The answer may point to IPR. It may point to ex parte reexamination. It may point to district court. And in some cases, it may point to doing nothing unless and until the business risk becomes concrete.

In 2026, ex parte reexamination deserves a place back on that decision tree.