Ex parte Baurin Reframes Obviousness-Type Double Patenting at the USPTO

Patent families often grow in stages. A company may file a foundational application, pursue related claims in continuations, and refine its protection as a product or research program develops. That strategy can be commercially sensible—but it also creates difficult questions about obviousness-type double patenting, commonly shortened to OTDP.

In August 2026, the U.S. Patent and Trademark Office designated Ex parte Baurin, Appeal 2024-002920, as precedential. The Appeals Review Panel reversed the Patent Trial and Appeal Board and reinstated an OTDP rejection involving related patent rights with different patent-term filing dates. The decision is important not because it creates a simple new formula, but because it shows how the USPTO is analyzing term, priority, issuance status, and the anti-harassment rationale behind the doctrine.

What happened in Ex parte Baurin?

The case involved U.S. Patent Application No. 17/135,529, directed to an antibody-like binding protein. The application was filed on December 28, 2020, and claimed priority through a chain reaching back to March 28, 2012. Based on that chain, its natural expiration date was March 28, 2032.

The examiner rejected claims 1–18 for OTDP over claims of U.S. Patent No. 10,882,922 in view of an additional reference. The reference patent had an April 13, 2017 patent-term filing date, issued on January 5, 2021, and was expected to expire on April 13, 2037, plus 70 days of patent term adjustment. The parties did not dispute that the pending claims would have been obvious over the cited combination.

The Board initially reversed, but the Appeals Review Panel reinstated the rejection. Its analysis focused on more than which application claimed the earliest priority date.

Why the Allergan exception did not control

The Federal Circuit’s Allergan decision recognized a limited protection against using a later-expiring patent as an OTDP reference against a first-filed, first-issued patent in the same family. Applicants have understandably examined whether that reasoning applies more broadly.

The panel concluded it did not apply here. The challenged application was not the first application actually filed, had not issued as a patent, and did not share the same patent-term filing date as the reference patent. Those factual distinctions mattered.

The practical lesson is that “earliest priority” and “first actual filing” are not interchangeable. A family may share a distant priority claim while individual applications have different filing histories and different statutory term calculations. Patent owners should map those facts before assuming that one family member is insulated from an OTDP rejection.

OTDP addresses term—and potentially repeated enforcement

OTDP is a judge-made doctrine intended to prevent an unjustified extension of exclusivity through patentably indistinct claims. A terminal disclaimer has traditionally addressed the problem by aligning expiration and requiring common ownership for the relevant period.

Ex parte Baurin also emphasized a second rationale: protecting the public from repeated enforcement by multiple assignees. The panel read Federal Circuit precedent as recognizing this “anti-harassment” concern independently, even where a challenged patent would not extend the practical patent term.

At the same time, the panel openly questioned whether that aspect of the doctrine may discourage innovation and suggested that the courts may eventually need to reconsider it. That observation is useful context, but it is not permission to disregard current OTDP law. For USPTO practice, the precedential outcome remains controlling unless later authority changes the framework.

What patent applicants should review now

Ex parte Baurin makes portfolio-level planning especially important. Applicants and owners should consider:

Actual filing dates. Identify the application that was first filed, not only the oldest priority date recited on a face page.
Patent-term filing dates. Continuations, divisionals, national-stage cases, and other related applications can produce different term calculations.
Issuance sequence. Whether a claim is pending or already patented can affect the analysis and the applicability of asserted exceptions.
Claim overlap. Compare the substance of claims across the family, including combinations with prior art that an examiner may use in an OTDP rejection.
Ownership and licensing plans. A terminal disclaimer can impose common-ownership consequences that affect transactions, enforcement, and portfolio restructuring.
Patent term adjustment. PTA may change the business significance of a disclaimer even when two assets arise from related subject matter.

These questions should be addressed early. Waiting until allowance can narrow the available choices, particularly when a terminal disclaimer could surrender valuable term or complicate a planned assignment.

A family tree is no longer enough

A conventional patent-family diagram shows priority relationships. For OTDP planning, that diagram should also show actual filing dates, patent-term filing dates, issuance dates, expected expiration dates, PTA, ownership, and potential claim overlap. That fuller timeline helps counsel assess which application may be used as a reference and what a terminal disclaimer would actually cost.

The same analysis can support broader decisions about continuation practice, licensing, and enforcement. Tucker Law can help businesses evaluate patent protection, assess risks before patent litigation, and coordinate a portfolio with the company’s wider intellectual property strategy.

The bottom line

Ex parte Baurin is a reminder that OTDP is not resolved by pointing to a shared priority chain or comparing expiration dates in isolation. The USPTO will examine the actual prosecution history, statutory term framework, issuance posture, and the doctrine’s anti-harassment rationale.

Businesses with layered patent families should review those relationships before the next office action or transaction creates urgency. To discuss how the decision may affect a pending application or an existing portfolio, contact Tucker Law.