GreyB's Take
The Baurin–Baumeister split suggests that ODP risk can no longer be assessed through filing and expiration dates alone. The ownership structure may determine whether an earlier filer can overcome the rejection or access a terminal disclaimer remedy.
01
ODP addresses two different concerns. The first prevents a patent owner from extending exclusivity through obvious variations of an existing invention. Neither Baurin nor Baumeister appears to create that type of term extension.
The second concern is harassment. Separately controlled owners could independently assert substantially similar inventions against the same party. In Baumeister, Merck Patent GmbH co-owned three reference patents and held rights that Ablynx and Sanofi could not independently bind through a terminal disclaimer.
02
The ARP is examining whether Allergan applies to unrelated patent families, whether separate ownership alone can sustain an ODP rejection, and whether examiners should calculate projected expiration dates during prosecution.
If Allergan extends beyond related patent families, first filers may receive protection wherever no term extension exists. If its application remains limited, ownership structure could continue determining whether an earlier filer has an available defence.
03
Companies involved in acquisitions, licensing arrangements, assignments, or joint development agreements should assess whether pending applications share inventive subject matter with patents that may become differently owned.
A transaction can change whether a terminal disclaimer remains available. Once ownership is divided, a remedy that existed before closing may become difficult or impossible to use.
I. The problem
When Filing First Is No Protection
Imagine a ‘Company A’ filed a patent application in 2012. They did everything right – they filed first, disclosed their invention honestly, and waited. Five years later, a different ‘Company B’ filed a patent on a similar invention. B’s patent issues before A’s. Now the USPTO is using B’s patent to reject A’s application. And ‘Company A’ cannot even file a terminal disclaimer to fix it, because they do not own B’s patent.
This is not a hypothetical. This situation sits at the center of a live dispute at the USPTO. An Appeals Review Panel (APR) convened in March 2026 is deciding whether applicants who file first can be permanently blocked from a patent because of who owns a later-filed reference. The outcome will affect every company managing a patent portfolio through acquisitions, licensing deals, or joint development arrangements.
Two cases, Baurin and Baumeister, had nearly identical facts. In both, the applicant filed first. In both, the reference patent was filed later and expires later. Yet Baurin won its appeal and Baumeister lost. The only real difference between the two cases was who owned the patents. In Baurin, both patents were owned by the same company. In Baumeister, there was some overlap in assignee and/or inventor, and some patents involved ownership of Merck Patent GmbH. Ownership appears to be the key differentiator in the two outcomes.
The applicants who file first, engage in no gamesmanship, can face an ODP rejection, not because they extended their patent term, but because a different company independently developed the same invention and filed second. In ordinary non-common ownership issues, a terminal disclaimer may not be available, leaving applicants with limited practical options.
II. The doctrine
Obviousness-Type Double Patenting: Goals and Dual Purpose
ODP is a judicially created doctrine with two distinct rationales. The first is term-extension: a patentee should not extend its monopoly by patenting obvious variations of an already-owned invention. This is the concern courts addressed in Gilead, Cellect, and Allergan, and the fix is a terminal disclaimer tying the second patent’s term to the first. The second rationale is harassment: even without term extension, two different owners of essentially the same invention can each independently sue the same infringer, and a terminal disclaimer filed by one owner against a patent it does not own is not available. Fallaux (2009) and Hubbell (2013) established that this harassment rationale applies even where no term extension exists.
What neither line of cases fully resolved is what “ownership” means for these purposes. Single-entity ownership is clearly common ownership. But what about a parent and a wholly owned subsidiary? A joint-venture partner? A co-inventor who has assigned her rights to a different entity than her co-inventor? The answer matters because, as Baumeister illustrates, partial or overlapping ownership is where the doctrine currently breaks down.
Key Distinction
The term-extension rationale operates at the level of patent term: if the earlier-filed patent expires first, there is no extension, and ODP does not apply regardless of ownership. The harassment rationale asks a different question entirely: whether two independent enforcement actions could arise from the same inventive concept. Where both patents are commonly owned, the patentee can enforce only once. Where they are separately owned, two independent entities can each sue the same infringer.
III. The collision
Party Portfolio & Strategic Positioning
Ex Parte Baurin concerns U.S. Application No. 17/135,529, directed to antibody-like binding proteins. The examiner rejected the application on ODP grounds, citing U.S. Patent No. 10,882,922 as the reference. The two patents are not in the same family and do not share a priority date. Their relationship, reduced to numbers, is as follows:
Ex Parte Baurin (Appeal 2024-002920)
Baurin Application (the rejected one)
Reference patent (used against Baurin)
Effective filing date
March 2012
Effective filing date
April, 2017
Expiration
March, 2032
Expiration (with PTA)
June, 2037
Filed first?
Yes
Filed first?
No- 5 years later
Expires first?
Yes
Expires first?
No- 5 years later
Both are commonly owned
The examiner’s position was that the claims of the reference patent and the application, while not identical, were not patentably distinct, and that the application would therefore extend the same inventive concept beyond the term of the reference patent. The applicant pushed back with the argument that Allergan held that a later-filed, later-issued patent cannot be used as an ODP reference against an earlier-filed patent.
The PTAB agreed with the applicant and reversed all ODP rejections, reasoning that if there is no extension of patent term, a patent is not a proper ODP reference. The examiner sought reconsideration on three grounds, the most consequential being that a hypothetical future risk of ownership change independently justified maintaining the ODP rejection, even where common ownership currently existed. The PTAB rejected all three arguments (Appeal: 2024-002920), holding that a speculative future ownership change cannot convert an otherwise improper ODP reference into a proper one. However, the durability of this reasoning is untested at the Federal Circuit. A joint development agreement could make the ownership change speculative, and whether the PTAB’s logic holds in that scenario remains an open question practitioners should watch.
Watch Point
Ex Parte Baumeister (Application 17/409,019)
Field
Application (Ablynx / Sanofi)
Reference Patents
Filing date
March 2012
All filed later
Expiration
June 25, 2032
All expire later
Term extension?
None
None
Ownership
Ablynx N.V. and Sanofi
Three reference patents also assigned to Merck Patent GmbH as co-assignee
ODP rejection outcome
Affirmed by PTAB. Appealed to Federal Circuit April 2026 (In re Ablynx N.V., Sanofi, No. 26-1333).
The core temporal structure of Ex Parte Baumeister is nearly identical to Baurin. The application (17/409,019), assigned to Ablynx N.V. and Sanofi, has a patent term filing date of June 25, 2012 and expires June 25, 2032. All six reference patents were filed later and will expire later. The applicant is not extending anyone’s term. In this dimension, Baumeister and Baurin are the same.
The difference is ownership. Three of the six reference patents, i.e US11603401B2, US11813307B2, and US12129308B2, are assigned not just to Ablynx and Sanofi, but also to Merck Patent GmbH as a co-assignee. As a co-assignee, Merck Patent GmbH holds independent assertion rights. Ablynx and Sanofi cannot file a terminal disclaimer that binds a co-assignee they do not control.
The PTAB applied the Fallaux and Hubbell and affirmed the ODP rejection solely on the harassment rationale. Ablynx and Sanofi appealed to the Federal Circuit in April 2026 (In re Ablynx N.V., Sanofi, No. 26-1333), arguing that the anti-harassment rationale has never been the sole basis for an ODP finding in this Court’s history, and that penalizing a foundational patent because a collaborator co-owns the follow-on patents inverts everything ODP was designed to prevent.
Side-by-Side Comparison
Factor
Ex Parte Baurin
Ex Parte Baumeister
Applicant's filing date
Earlier
Earlier
Reference patent filing date
Later
Later
Reference patent expiration
Later than applicant
Later than applicant
Term extension concern?
None
None
Same patent family?
No. Unrelated families.
No. Unrelated families.
Ownership
Commonly owned
Non-identical / partly overlapping. Some patents also involved Merck Patent GmbH.
ODP rejection?
No. Reversed by PTAB.
Yes. Affirmed by PTAB.
Current status
Pending ARP review
Further appealed to Federal Circuit
Similar facts, opposite results. The only variable that changed was ownership. The contradiction between Baurin and Baumeister did not go unnoticed. In March 2026, USPTO Director Squires convened an Appeals Review Panel to resolve it.
The contradiction between Baurin and Baumeister did not go unnoticed. In March 2026, USPTO Director Squires convened an Appeals Review Panel (ARP) to resolve it. The ARP is examining whether Allergan’s reasoning extends to unrelated patent families, whether separate ownership alone is enough to sustain an ODP rejection, and whether examiners should be required to calculate projected expiration dates during prosecution.
Allergan held that a first-filed, first-issued, later-expiring claim cannot be invalidated by a later-filed, later-issued, earlier-expiring reference claim having a common priority date. It does not limit it to a same-patent family.
If the ARP extends Allergan to unrelated families, first-filers gain protection regardless of ownership wherever no term extension exists. If it limits Allergan to same-family patents, Baumeister’s outcome holds in the non-common-ownership scenario, and the ownership structure becomes the remaining variable determining whether a first-filer has any protection at all.
Why Separate Ownership Maps to Harassment, Not Term Extension
The harassment rationale asks whether two independent enforcement actions could arise from the same inventive concept. Where both patents are commonly owned, the patentee can enforce only once. Where they are separately owned, two independent entities can each sue the same infringer. The fact that neither entity was extending its own term is irrelevant; the risk the doctrine addresses is defendant exposure, not patentee gain. What Baumeister leaves open is the threshold question: does separate ownership raise the harassment concern per se, or must there be evidence of a realistic enforcement threat?
IV. Practical implications
What This Means for Practitioners
01
Map ownership before the ARP rules
02
Treat ownership changes as a transaction risk
Before any acquisition, licensing deal, or joint development agreement closes, confirm whether pending applications share inventive subject matter with patents that will no longer be commonly owned afterwards. Once the transaction closes, a terminal disclaimer cure that was previously available may no longer be fileable.
03
Preserve your prosecution record
Act Before the ARP Rules
Map your ODP ownership exposure now
The risk identified in Baumeister exists in any portfolio that has passed through an acquisition, licensing deal, or joint development arrangement. GreyB can run the ownership audit on your pending applications before the ARP rules and before a cure becomes unavailable.