On August 6, 2026, the USPTO Appeals Review Panel (ARP) reinstated nonstatutory double patenting (NSDP) rejections against Sanofi’s application for antibody-like binding proteins. This precedential decision has significant implications for life sciences companies developing and improving upon innovative therapies.
NSDP is an incredibly complex doctrine that seeks to place limits on patentees obtaining multiple patents to patentably indistinct inventions. It is predicated on two rationales: first, that patentees should be prohibited from improperly extending the duration of the exclusivity granted by a patent, since the public should be free to practice an invention and obvious variations thereof upon expiration of the patent. Second, NSDP seeks to prevent harassment in patent infringement suits by multiple patent owners claiming rights in essentially the same invention.
The ARP reinstated the NSDP rejections and found that, under current Federal Circuit precedent, the risk of harassment remains a valid reason for rejecting patent claims, even if there is no extension of patent term. However, the Panel also recognized the stifling effect that this anti-harassment basis may have on future innovation. The Federal Circuit is expected to address these issues soon in In re: Ablynx N.V., which could bring much-needed clarity for innovators.
Ex parte Baurin
The patent application at issue in Ex parte Baurin was rejected for NSDP based on related patents in its portfolio, even though the application would expire before the reference patent.
In November 2024, on appeal, a PTAB panel reversed the NSDP rejections, concluding that because any patent issuing from the pending application would expire in 2032—five years before the reference patent’s 2037 expiration—granting the application claims could not extend patent term and therefore did not trigger NSDP under the doctrine’s “fundamental purpose.”
In March 2026, the Director convened an ARP and granted sua sponte rehearing, inviting additional briefing from the applicant and amici on several issues, including whether the risk of separate ownership and harassment by multiple assignees is an independent basis for NSDP during prosecution, even when there would exist no timewise extension of patent term.
The ARP’s decision relied on three Federal Circuit cases that have recognized the anti-harassment rationale as an independent basis for double patenting:
In re Fallaux, 564 F.3d 1313 (Fed. Cir. 2009): The court acknowledged that the term-extension rationale had “limited force” post-URAA (i.e., as patent expiry was determined based on effective filing date, rather than issue date), but nonetheless affirmed NSDP rejections based on potential harassment by multiple assignees, even where the appealed claims had an earlier expiration than the reference patents.
In re Hubbell, 709 F.3d 1140 (Fed. Cir. 2013): The court “reaffirmed” the multiple-assignee harassment rationale and sustained NSDP rejections where the application and reference patent lacked common ownership, again in a situation without obvious term extension.
In re Cellect, 81 F.4th 1216 (Fed. Cir. 2023): The Federal Circuit upheld a NSDP rejection on the basis that a terminal disclaimer assuring common ownership would have been required “even if the patents had the same expiration date,” due to the risk of divided ownership and multiple suits.
The ARP rejected the PTAB’s stance that these statements were mere dicta. In the Panel’s view, characterizing the harassment discussion as dicta would be to conclude that those NSDP affirmances rested on no articulated rationale at all, since the NSDP rejections in Fallaux and Hubbell were based on later-filed, later-expiring reference patents.
Given the conceded lack of patentable distinctness and the potential for split ownership in the future, the ARP in Baurin held that the reference patent is a proper NSDP reference despite its later expiration, and that NSDP rejections against the pending application must be maintained. Because there was no potential extension of patent term in play here in Baurin, the ARP’s decision means that, for now, the USPTO can continue to reject claims based merely on the risk that patents covering similar inventions could end up with different owners, potentially exposing licensees and innovators to multiple lawsuits.
Will the Future Bring Clarity?
Despite this result, the ARP makes clear that its decision is bound by precedent, and it strongly signaled its hesitation to use the mere risk of future harassment by multiple owners as a freestanding justification for applying NSDP. Absent evidence suggesting that a patentee has indeed split the ownership of inventions that are not patentably distinct, the ARP finds that the rationale is based in mere speculation. Moreover, the ARP agrees with amici that the anti-harassment rationale discourages future innovation, improving existing technologies, and collaborations between institutions. The ARP’s decision openly invites the Federal Circuit to clarify whether the risk of harassment alone should justify double patenting rejections, especially when there is no extension of patent term. We are hopeful that the court will provide guidance that balances the need to prevent abusive litigation with the realities of innovation and collaboration in the life sciences sector.
Why Does This Matter For Our Clients?
For companies developing new therapies and building on existing discoveries, this decision highlights the importance of carefully managing patent families and ownership structures. Even if your new patent is slated to expire before an older one, you could still face double patenting rejections if the claims are not patentably distinct. This can impact your ability to protect improvements without jeopardizing existing patents and their term, to license technology, and to avoid costly disputes.
While we will continue to monitor developments regarding NSDP, we recommend reviewing your patent strategies for potential double patenting risks. Consider the impact of terminal disclaimers in your patent estate, since these impact future licensing or enforcement options. You should also carefully manage inventorship and ownership across your patent estate to minimize the risk of split ownership and related challenges. These steps can help you protect your innovations and business interests in a changing legal landscape.