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The doctrine of obviousness-type double patenting (“OTDP”) is one of the most complicated aspects of U.S. patent law, but the U.S. Court of Appeals for the Federal Circuit soon will have an opportunity to limit when OTDP can arise. Will it take this opportunity to simplify U.S. patent law, streamline examination, and further incentivize follow-on innovation?

Under current USPTO guidance set forth in MPEP § 804, OTDP is grounded in public policy that has two aims: “to prevent the unjustified extension of patent exclusivity” and “to prevent the possibility of multiple suits against an accused infringer by different assignees of patents claiming patentably indistinct variations of the same invention.” Two appeals pending before the Federal Circuit ask the court to revisit whether the theoretical possibility of litigation harassment should be a “standalone” basis for OTDP.

The Ex parte Baurin Decisions

In Ex parte Baurin, the original panel decision of the USPTO Patent Trial and Appeal Board (PTAB) issued November 11, 2024, reversed six OTDP rejections that had been made in U.S. Patent Application No. 17/135,529 based only on the possibility of litigation harassment. The opinion cited the Federal Circuit decision in Allergan USA, Inc. v. MSN Labs. Private LTD., 111 F.4th 1358 (Fed. Cir. 2024), for the principle that patents granted from later-filed applications with later expiration dates do not raise OTDP issues for claims with an earlier expiration date.

Just over a year later, in a 2-1 decision issued December 18, 2025, a reconstituted panel denied a request for rehearing, effectively upholding the original panel decision.

Perhaps in response to the attention Baurin was receiving — and its inconsistency with other ex parte PTAB decisions — Director Squires convened an Appeals Review Panel (ARP) to “sua sponte” review the Baurin decision. In the decision issued August 10, 2026, the ARP reversed the previous PTAB panel decisions, and upheld the original OTDP rejections.

On the merits, the ARP disagreed with the PTAB panel decisions on two main points:

• The ARP found the application at issue does not fall under Allergan, because it is not the first-filed (by actual filing date), first granted case in its family — and indeed has not yet granted
• The ARP found that “[b]inding Federal Circuit [p]recedent” holds that the theoretical possibility of litigation harassment can be a “standalone” basis for OTDP

The applicant has appealed the ARP decision to the Federal Circuit.

Beyond Baurin

The ARP decision in Baurin might not be remarkable, but the last 10 pages of the opinion are making headlines. There, the ARP invites the Federal Circuit to provide “clarification” on whether its precedents really should be interpreted as permitting OTDP rejections “based solely on the anti-harassment rationale,” and offers policy reasons why the Federal Circuit should eliminate or constrain OTDP when there is no issue of term extension:

• OTDP rejections based solely on the anti-harassment rationale are speculative and may unjustly encumber patent rights
• If any “litigation harassment” does arise, courts could invalidate the patents under OTDP
• Using later patent families to invalidate earlier patent families discourages follow-on research and collaboration and may harm innovation
• If OTDP rejections based solely on the anti-harassment rationale are not eliminated, they should be limited to circumstances where (i) the applicant has a history of litigation harassment or (ii) OTDP can be found under the two-way test (obviousness runs both ways)

The ARP decision points out that the Federal Circuit can address these issues in the pending appeal in In re Ablynx/Ex Parte Baumeister, but the USPTO’s brief defending the rejections on appeal in that case dodged arguments based on policy.

In re Ablynx/Ex Parte Baumeister

In re Ablynx is the pending Federal Circuit appeal of the PTAB panel decision in Ex Parte Baumeister. There, the PTAB upheld six OTDP rejections made in U.S. Patent Application No. 17/409,019 that were based only on the anti-harassment rationale. The USPTO’s opening appellee brief was filed a few days after the ARP decision in Baurin was published, but argues in support of the OTDP rejections based on the following arguments:

• Federal Circuit precedent “mandates” OTDP rejections “even when there is no unjustified time-wise extension because a risk of harassment remains”
• None of the “narrow circumstances” where the Federal Circuit has limited the application of OTDP apply here
• “Appellants policy arguments are foreclosed” by Federal Circuit precedent

The brief’s only nod to the ARP decision responds to Appellant’s “policy arguments” and simply states:

Whatever the merits of those policy arguments, the Board faithfully applied this Court’s binding precedents.

Will The Federal Circuit Limit OTDP To Term Extension Scenarios?

Both the ARP decision in Baurin and the USPTO brief in Ablynx rely on In Re Fallaux, 564 F.3d 1313 (Fed. Cir. 2009), as the primary Federal Circuit decision upholding OTDP based only on the anti-harassment rationale. But does Fallaux have to be read that way?

The Fallaux decision discussed and endorsed the anti-harassment rationale, but the main issue presented was whether the OTDP rejection at issue should have been based on the two-way test for obviousness instead of the one-way test. Ablynx raised this in their opening appellate brief. Thus, if the Federal Circuit is inclined to limit OTDP, it could explain that Fallaux only addressed which test for obviousness should be used, not whether the risk of harassment alone can support OTDP. Indeed, the Fallaux decision only raised the anti-harassment rationale in response to arguments that “cases refusing to allow applicants to rely on the two-way test are distinguishable because unlike the applicants in those cases, Dr. Fallaux is not seeking an unjustified patent term extension.”

The Federal Circuit is likely to decide at least Ablynx in early- to mid-2027. Applicants currently facing OTDP rejections based only on the anti-harassment rationale may want to avoid filing a Terminal Disclaimer or taking other final action until the Federal Circuit—and possibly the Supreme Court—have ruled on the issue.

Attorneys at �鶹ֱ�� have extensive experience counseling clients on OTDP in their own and competitor patent portfolios. Contact the author or your �鶹ֱ�� attorney for more information.