Biotech Patent Continuations: 2025 Terminal Disclaimer vs Double Patenting

This guide explains how terminal disclaimers cure obviousness-type double patenting and how to run the child-to-parent ODP check before paying a continuation issue fee.

It also separates the 2025-2026 filing collapse caused by USPTO docketing changes from any change in ODP doctrine.

How ODP and Terminal Disclaimers Actually Work

Under obviousness-type double patenting, the claims of your own earlier patent or co-pending application can make a later patent unpatentable or invalid, even though that earlier right is not prior art under Sections 102 or 103. The test is whether the two claim sets are "patentably distinct": if the later claims would have been obvious over the earlier claims, the later patent is exposed. The doctrine exists for one reason—no invention gets a second, later-expiring term (patentlawyer.io, 2026-10-09).

A terminal disclaimer cures the rejection, but only at a price. It surrenders term and makes the disclaimed patent unenforceable whenever it is not commonly owned with the reference patent; without common ownership, no disclaimer is available at all. That makes common ownership a condition of the cure, not merely a convenience (patentlawyer.io).

Exposure runs child-to-parent. Under In re Cellect (Fed. Cir. 2023) and Allergan USA v. MSN Laboratories (Fed. Cir. 2024), a later-issued child whose term adjustment carries it past an earlier-expiring sibling is exposed, while a first-filed, first-issued parent is not. The direction of exposure therefore follows issuance and term, not the order in which the family was conceived.

For a portfolio manager, the stakes are quiet ones. A continuation that looks healthy on the docket may already be tied to a sibling by a terminal disclaimer, may have picked up term adjustment that makes it a target, or may have been sold in a carve-out that broke common ownership. None of it shows until an acquirer or a litigant looks (patentlawyer.io).

So the cure is narrower than it first appears: a terminal disclaimer is available only where common ownership exists, and even then it costs term. Where the child is not commonly owned with the earlier-expiring sibling, the disclaimer is unavailable and the child remains exposed unless its claims are patentably distinct from that sibling.

The Evidence: What the Record Shows

The record’s operative explanation is procedural: Patently-O reports a USPTO docketing change behind the terminal disclaimer collapse, and that change is the driver of the drop in filings rather than a change in ODP doctrine itself. In other words, the collapse is best read as an operational response to how the Office dockets and processes disclaimers, not as evidence that the underlying double-patenting rule has shifted.

That reading is reinforced by Lemley & Ouellette’s Patently-O guest post, which observes that continuations may have much narrower claims or cover very different aspects of an invention, effectively a divisional by another name, and that many applicants pursue a strategy of getting one invention granted. Those observations show that continuation practice already accommodates varied claim scope and portfolio tactics, so a filing drop can follow docketing friction without requiring a doctrinal explanation.

Ex parte Baurin, identified in the record as a USPTO Appeals Review Panel precedent, belongs in the same picture as a sign that the doctrine is in motion, but it should not be treated as the cause of the disclaimer collapse. The docketing change remains the operational cause; Baurin is better used as a reminder to check the current procedural posture before assuming a stable practice.

For a portfolio check, separate three questions: whether the drop tracks the docketing change, whether the continuation’s claims are materially narrower or directed to a different aspect of the invention, and whether common ownership and term surrender remain acceptable. If the answer to the first is yes, the evidence supports a procedural explanation; if the answer to the third is no, a terminal disclaimer may not be available at all.

Accordingly, before paying any issue fee on a continuation, treat the docketing change as the first hypothesis for changed disclaimer behavior, then verify claim scope and ownership before concluding that ODP doctrine has moved.

Options Compared: Amend, Disclaim, or Abandon

When an obviousness-type double patenting rejection appears at allowance, the practical choice is among three paths: amend the claims, file a terminal disclaimer, or walk away. The right path turns on whether the later-filed claims can be made patentably distinct, whether common ownership still exists, and whether the Section 121 safe harbor applies. Run that comparison before paying the issue fee; a continuation that looks healthy on the docket may already be tied to a sibling by a terminal disclaimer.

Amending to a non-obvious limitation is the only option that preserves term, but it is easy to do wrong. Dropping one element from a parent claim produces a genus that reads on the parent’s species, so the amendment must add a limitation the parent does not teach; merely deleting or broadening language will not cure the rejection (patentlawyer.io). In other words, the amendment must narrow or redirect the claim in a way the parent does not already teach, not simply remove an element.

As explained above, a terminal disclaimer surrenders term and requires common ownership; before treating it as a fallback, verify the ownership chain, since a carve-out that breaks common ownership makes no disclaimer available at all.

The Section 121 safe harbor is absolute but narrow: it protects divisionals filed after a restriction requirement, provided every patent in the chain stays consonant with that restriction. Where the facts fit, no disclaimer is needed; where the chain has drifted from the restriction, the harbor is lost. The harbor is valuable because it is absolute within its narrow facts, but it does not rescue a chain that has departed from the restriction.

If none of those cures is available—no distinct limitation can be added, no common ownership supports a disclaimer, and no safe harbor applies—the remaining option is to abandon or decline the issue fee rather than accept a term surrender or an unenforceable patent. Abandonment is not a failure mode to avoid at all costs; it can be the rational choice when the remaining term or claim scope does not justify the surrender.

Costs and Numbers That Matter

As priced above, the terminal disclaimer's cost is both irreversible term and a continuing common-ownership condition; the remaining question in this section is which term source and forum actually drive the risk.

The extension type determines whether ODP is even the right problem. Per patentlawyer.io (2026-10-09), a Hatch-Waxman extension under Section 156 (PTE) does not create ODP invalidity and survives a disclaimer, while PTA-driven term is the Cellect exposure. Before filing or refusing a disclaimer, identify whether the extra term comes from Section 156 or from PTA; the two are not interchangeable for ODP risk.

The forum determines how ODP can be raised and how hard it is to prove. According to patentlawyer.io (2026-10-09), ODP cannot be raised in IPR, is available in ex parte reexamination, and must be proved by clear and convincing evidence in district court. A disclaimer's value and an ODP challenge's burden are therefore forum-specific; do not carry one forum's rule into another.

The cost of being wrong runs both ways. Disclaiming unnecessarily surrenders term that cannot be recovered and imposes an ownership lock; leaving a real ODP issue unaddressed leaves the patent exposed in forums where ODP is available and provable. The practical check is to match the extension type and the forum to the actual risk before paying the issue fee.

Ownership is part of the cost, not an afterthought. Because a disclaimer is unavailable without common ownership and unenforceable when common ownership is lost, verify the ownership chain before relying on it; a carve-out or assignment that breaks common ownership can turn a filed disclaimer into a dead letter.

What the Evidence Does NOT Establish

The available sources for this article does not contain a quantified figure for the terminal-disclaimer collapse: no percentage, count, or rate of decline appears in the available sources. Any citation of a magnitude should therefore be verified directly at patentlyo.com before it is used, and the absence of a number should not be backfilled with an estimate, range, or “about” figure.

Patently-O is identified as naming a USPTO docketing change as the cause, but the snippet does not carry the change’s full text or its effective date. Before relying on that procedural explanation, check the Federal Register and USPTO Official Gazette notices for the operative language, applicability, and date.

The available sources also does not establish the Appeals Review Panel’s full reasoning in Ex parte Baurin. The available reference is truncated, so the decision’s complete analysis, scope, and any limits it places on terminal disclaimers should be read from the decision itself rather than summarized from the snippet.

When a source names a cause but not a magnitude, the safe practice is to cite the cause and mark the magnitude as unverified. Likewise, when a procedural change or panel decision is referenced only in part, its effective date and reasoning control how far the reference can be relied on.

This section records those gaps rather than conclusions. It does not restate the child-to-parent exposure rule, the amend-or-disclaim options, the PTE-versus-PTA distinction, or forum-specific proof standards, because those points are addressed elsewhere.

A Continuation ODP Check

Before paying the issue fee on a continuation, run the child-to-parent ODP check on the actual claims and ownership chain. In this example, the parent was filed in 2018, issued in 2020, and expires in 2038; the continuation was filed in 2021, allowed in 2026, has a base expiry of 2041, and carries 400 days of PTA that push expiry to 2042. The child therefore expires after the parent, so the check is not academic; the later expiry is what creates the exposure window.

Checkpoint 1 is patentable distinctness. Compare each child claim to every parent claim; if any child claim would have been obvious over the parent claims, ODP attaches (patentlawyer.io, 2026-10-09). The comparison must be claim-by-claim, not a summary of the specification, because one obvious dependent claim can put the whole continuation at risk. Keep the comparison in the file so an acquirer or litigant can see the work later.

Checkpoint 2 is common ownership. If the continuation was sold in a carve-out that broke common ownership, no terminal disclaimer is available at all. That makes the ownership answer dispositive: a non-distinct child with split ownership has no disclaimer path, while a non-distinct child with common ownership still has the disclaimer question to resolve before issuance. The check therefore has two independent failure modes, and either one can stop the file.

Close the check in writing: record the claim comparison, the ownership chain, and the expiry dates. If the claims are distinct, the file can move to issue; if they are not, the ownership answer determines whether a disclaimer is even available, and that answer should be settled before the issue fee is paid. This is a pre-issuance control, not a post-grant repair.

Because the continuation is already allowed, the issue fee is the last ordinary checkpoint; after payment, the patent issues with whatever ODP exposure the comparison revealed. Running the check now costs a comparison and an ownership review, not a later dispute.

Decision Rules for Continuation Filings

Before paying any issue fee on a continuation, compare the child’s claims with each earlier-expiring sibling and confirm common ownership. These four rules convert that check into an action; they state what to do, not why the doctrine reaches the child or what the record shows about filing trends.

If the child’s claims are not patentably distinct from an earlier-expiring sibling and ownership is common, file a terminal disclaimer before issue; do not wait for a rejection. If ownership is not common, no terminal disclaimer is available, so amend to a non-obvious limitation or abandon the conflicting claims.

If the child’s extra term is PTA and it pushes expiry past a sibling, treat the child as the Cellect target and either disclaim or amend. If the child’s claims are patentably distinct from every earlier-expiring sibling, no terminal disclaimer is needed on ODP grounds for that pair.

Apply the rules in order: distinctness first, ownership second, term third. That order keeps a disclaimer from being filed where no ODP exposure exists and keeps an amendment from being skipped where ownership blocks the disclaimer.

Verify common ownership from the assignment record and any carve-out before relying on a disclaimer; a label in the file is not enough. Run the same check again if claims are amended after the first comparison, because a narrowing or broadening change can move a claim across the distinctness line.

Keep the action tied to the pre-issue moment: when the first rule applies, file before issue rather than treating the problem as curable after grant.

Frequently Asked Questions

What must a terminal disclaimer do to cure ODP?

Terminal disclaimer cures ODP only by surrendering term and enforcing common ownership.

When should the child-to-parent ODP check be run?

Run the child-to-parent ODP check before paying any continuation issue fee.

What must be compared during the child-to-parent ODP check?

Compare child claims to every earlier-expiring sibling; if not patentably distinct and not commonly owned, resolve before payment.

What caused the 2025-2026 collapse in disclaimer filings?

The 2025-2026 collapse in disclaimer filings reflects a USPTO docketing change, not an ODP doctrine change.

How should the 2025-2026 filing drop be treated?

Treat the filing drop as procedural; ODP still bars one patent per invention unless claims are patentably distinct.

How can a slight broadening create ODP?

A slight broadening can create ODP: dropping one parent element yields a genus reading on the parent's species.

Quick answers

Also worth reading: The USPTO 2024 Terminal Disclaimer Rule: The 214-Day Gap Trap: USPTO 2024 Terminal Disclaimer Rule: · 2024 Terminal Disclaimer: Clustering Beats Costly ODP: 2024 Terminal Disclaimer: Clustering Beats · Quantum Computing Patents Redefining Non-Obviousness Standards in Post-Moore's Law Era: Quantum Computing Patents Redefining Non-Obviousness