Amicus, Sanofi Urge USPTO Appeals Panel to Uphold Ex Parte Baurin’s Approach to ODP Analysis

Amicus briefs in the U.S. Patent and Trademark Office’s (USPTO’s) review of issues raised by a 2025 Patent Trial and Appeal Board (PTAB) rehearing decision regarding the judicially-created doctrine of obviousness-type double patenting (ODP) were due on Friday, March 27. At least one amicus is urging the Office to affirm the decision’s holding and clarify that the focus should be on “whether there is any unjustified extension of term when determining if an ODP rejection is appropriate” in order to create more consistent outcomes in examination and to harmonize the approaches of the PTAB and examining corps.

The USPTO announced earlier this month that it will convene an Appeals Review Panel (ARP) to examine the issues raised by Ex Parte Baurin, issued on December 18, 2025. There, the PTAB denied an examiner’s request for reconsideration of the Board’s November 8, 2024, decision reversing the examiner’s ODP rejections of several claims of U.S. Application No. 17/135,529, directed to antibody-like binding proteins. The Board found that the reference patent the examiner relied upon for its ODP analysis, U.S. Patent No. 10,882,922, was not a proper ODP reference because it was later filed and later expiring than the application in the present case.

The rejection was based on the Board’s interpretation of Allergan USA, Inc. v. MSN Labs. (Fed. Cir. 2024), which 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.” The CAFC explained that the purpose of the ODP doctrine is “to prevent patentees from obtaining a second patent on a patentably indistinct invention to effectively extend the life of a first patent to that subject matter”—not to block a first-issued patent that expires later, as was the case here.

The examiner in Ex Parte Baurin requested rehearing based on the argument that the Board “misapprehended” the holding in Allergan. The examiner argued that, while the claims of the ‘922 reference patent and the claims in the application were not identical, they are not patentably distinct and the application’s claims would have been an obvious alternative to a skilled artisan. The applicant countered that the ‘922 reference patent does not qualify as a proper ODP reference because the application’s claims have a filing date of March 28, 2012, corresponding to the filing date of U.S. Application No. 13/433,033, while the ‘922 patent has a filing date of April 13, 2017, corresponding to the filing date of U.S. Application No. 15/487, 243. And with respect to expiration dates, due to terminal disclaimers filed with the Ex parte Baurin application, “any patent issuing from the instant application cannot extend beyond March 28, 2032,” while the ‘922 patent “has a 20-year statutory term that ends on April 13, 2037 and received 70 days of PTA.”

The PTAB ultimately agreed with the appellant again on rehearing, noting that, “[w]hile the facts of Allergan are somewhat different than here because the ‘922 patent and the application before us do not share a priority date or even stem from the same application family, we find the reasoning compelling.” Squires then granted sua sponte rehearing to address issues raised by the rehearing decision, with a panel consisting of Squires, the Acting Commissioner for Patents and the PTAB’s Chief APJ.  The order asked amici to address the following information in particular:

“1) the applicability, if any, of Allergan USA, Inc. v. MSN Laboratories Private Ltd., 111 F.4th 1358 (Fed. Cir. 2024), to the facts of this appeal, and consideration of what constitutes “first-filed” for OTDP purposes under facts different than those presented in Allergan;

(2) whether examiners should determine projected expiration dates to support OTDP rejections during prosecution; and

(3) whether the risk of separate ownership and preventing potential harassment by separate owners of claims to obvious variants of an invention is an independent basis that supports an OTDP rejection during prosecution.”

Anthony Prosser of Knowles Intellectual Property Strategies, speaking on his own behalf and not for his company, told the ARP in his brief that “[o]ver a dozen judges have dealt with non-statutory obviousness type double patenting (ODP) since the Allergan v. MSN decision and have reached a similar conclusion as the Board in Ex parte Baurin.” Prosser reviewed several CAFC, district court and PTAB decisions following the reasoning of Ex parte Baurin and distinguished the decisions in which judges have read Allergan more narrowly, such as Ex parte Baumeister, Appeal 2026-000193 at 17 (PTAB Nov. 21, 2026), which is currently on appeal to the CAFC. According to Prosser’s brief, the case law outlined in the brief, while not controlling of the ARP’s decision, demonstrates that “the interpretation of Allergan v. MSN in Ex parte Baurin represents a consensus interpretation of the Allergan decision,” and should be upheld.

In its response to Squires’ order, the appellant, Sanofi, also addressed the examiner’s argument regarding future separate ownership or withdrawal of terminal disclaimers, which the Board found to be an insufficient basis to support an ODP rejection and irrelevant where the ODP reference is not proper. “While there may be a policy concern of risk of separate ownership underlying the non-alienation provision for terminal disclaimers, no court has held that risk of common ownership is a sole justification for upholding an ODP rejection that is not based on a proper reference patent,” wrote the PTAB in its rehearing decision.

Sanofi reiterated this position and said that once a reference has been determined not to be a proper ODP reference, the inquiry ends and concerns over separate ownership or terminal disclaimer become irrelevant, even if it results in the patent term being extended. And the Allergan decision itself supports this view, said Sanofi. “[T]he fundamental purpose of the OTDP doctrine (i.e. preventing an unjustified timewise extension of a patentee’s monopoly) – not the possibility of separate ownership – is the guiding principle for determining whether a reference qualifies as an OTDP reference.”

During a PTAB Listening Session held today on the PTAB and Life Sciences—the first of three Listening Sessions the Office will be holding in the coming weeks—USPTO Deputy Director Coke Morgan Stewart said the Office has received all of the amicus briefs and will be reviewing them in the coming days.

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