Professors Push Back in Review of PTAB Rehearing Decision on ODP

Amicus briefs have now been posted to the U.S. Patent and Trademark Office (USPTO) site in Ex Parte Baurin, a 2025 rehearing decision of the Patent Trial and Appeal Board (PTAB) with respect to obviousness-type double patenting (ODP) that is being reviewed by an Appeals Review Panel (ARP).

While most of the amici are arguing in favor of the Board’s analysis, one brief submitted by Professors Mark Lemley and Lisa Larrimore Oullette contends that U.S. Court of Appeals for the Federal Circuit (CAFC) precedent supports the examiner’s rejections and that Allergan’s holding is inapplicable here.

Baurin Background

The USPTO announced last month that it would sua sponte convene the ARP to examine the issues raised by the rehearing decision, issued on December 18, 2025. The decision 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’ order convening the ARP specifically asked amici to address:

“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.”

The ARP panel consists of Squires, the Acting Commissioner for Patents and the PTAB’s Chief APJ.

Professors Respond to Opponents of ODP Limits

Citing cases such as In re Fallaux and In re Hubbell, Lemley and Oullette argue that the CAFC has “repeatedly sustained ODP rejections where the reference patent has a later priority and patent-term filing date than the application under examination” and urge the ARP to affirm the examiner’s ODP rejections. Another PTAB panel, in In re Baumeister, reached the opposite conclusion to the Baurin panel, relying on Fallaux.

Amicus Anthony Prosser, writing in favor of the Board’s analysis, acknowledged Baumeister, but said that holding was based on an old (2009) judicial opinion with “limited applicability to the facts.”

“[T]he Fallaux case is largely focused on whether the two-way or one-way test should be applied for the ODP rejection of the Fallaux claims and not whether the reference patents were appropriate,” wrote Prosser. Furthermore, Baumeister is on appeal to the CAFC and awaiting more “clarity.”

Lemley and Oullette also claim that “the facts of Allergan bear little resemblance to this appeal” because, here, “the reference patents arise from separate application families and do not share a common priority date with the applicaiton on appeal,” while in Allergan, “the challenged patent was the first-filed application in a priority chain, so that the later-filed continuations were derivative of the very patent they were being used to attack.” Additionally, the Allergan patent was first to issue, while in Baurin “the reference patents issued before the application on appeal has even resulted in a patent.”

The Lemley-Oullette brief also argues that “double patenting is a large and growing practice” and warns of the alleged consequences of affirming the Baurin panel’s holding.  “A rule immunizing earlier-filed applications from ODP, as the Baurin panel adopted, would remove a significant check on patentably indistinct patents across independent application families for some of the patents with the highest stakes,” says the brief.

The professors add that their opponents’ claims that crackdowns on ODP harm innovation and reduce incentives to patent follow-on inventions are unsupported by empirical evidence. “[T]he opponents of [more stringent restrictions on double patenting] have made no showing that the current rule is benefitting the American economy compared with a more restrictive practice,” says the brief.

Other amici that have submitted briefs include the Biotechnology Innovation Organization; Canon, Inc. et. al.; Regeneron Pharmaceuticals et. al.; the IP Section of the Bar Association of the District of Columbia; Michael O’Brien; PhRMA; GlaxoSmithKline; Amgen, Inc.; and the Japan Pharmaceutical Manufacturers Association.