In a precedential decision issued on August 13, 2024, the U.S. Court of Appeals for the Federal Circuit 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.1
Obviousness-Type Double Patenting
Obviousness-type double patenting (ODP) is a judicially created doctrine dating back to the 19th century that prevents two patents from granting on patentably indistinct inventions. This doctrine was established to ensure that if the government grants exclusive rights in the form of a patent, once that patent expires, the public is free to use the patented invention. According to the decision, if the inventor obtains a second patent that is patentably indistinct from the first patent, then the exclusive right is unjustly extended.
An ODP analysis requires considering the difference between the claim(s) of the patent or application at issue, and the claim(s) of a reference patent or application. If the difference would have been obvious over the reference claim(s), then the claim(s) of the patent or application at issue are patentably indistinct and invalid or unpatentable under the ODP doctrine.
Allergan v. MSN Laboratories
In Allergan v. MSN Laboratories, regarding ODP, the Federal Circuit analyzed whether a later-filed, later-issued claim could properly serve as a reference claim in an ODP analysis.
Allergan sells eluxadoline (brand name Viberzi®) for the treatment of irritable bowel syndrome with diarrhea. Eluxadoline and methods of using eluxadoline are covered by claim 40 of U.S. patent 7,741,356 ('356 patent), claim 33 of U.S. patent 8,344,011 ('011 patent), and claim 5 of U.S. patent 8,609,709 ('709 patent). The '356 patent was issued from an application filed in 2005, but because of examination delays, the '356 patent accrued patent term adjustment (PTA) and expires in 2026. The '011 and '709 patents were issued from applications that claim priority to the '356 patent and expire in 2025. All of these patents share the same priority date. A schematic of the relationship between these patents is provided in the figure below, which shows the filing date (circle), issue date (triangle), and expiration date (star) of the patents at issue, as well as the relationship among the patents within the family (continuation or divisional application).
Sun Pharmaceutical submitted an Abbreviated New Drug Application (ANDA) seeking U.S. Food and Drug Administration approval to sell a generic version of Viberzi®, and in doing so, certified that the claims of the '356 patent are invalid or would not be infringed by Sun Pharmaceutical’s generic product. Allergan sued Sun Pharmaceutical, asserting that the filing of the ANDA directly infringed claim 40 of the '356 patent. In turn, Sun Pharmaceutical alleged that claim 40 of the '356 patent is invalid under the ODP doctrine over claim 33 of the '011 patent and claim 5 of the '709 patent.2 Allergan disputed whether the claims of the later-filed, later-issued, '011 and '709 patents were proper ODP references.
Federal Circuit’s Discussion of ODP Principles
In determining whether a claim is a proper ODP reference, the court considered the circumstances under which the ODP doctrine was established over a century ago. The ODP doctrine originated when a patent’s term was measured from its issuance date. However, since Congress passed the Uruguay Round Agreements Act of 1994 (URAA), a patent’s term is measured from its filing date. The court noted that post-URAA, when two patents share a priority date, as is the case in Allergan, there is less risk of an unjustified extension of patent term because the two patents are expected to expire on the same day.
In Allergan, even though the '356, '011, and '709 patents share a priority date, the '356 accrued PTA and thus expires about 15 months after the '011 and '709 patents. When determining whether the 15 months of additional patent term was unjustified, the court articulated its view as to the key rationale of the ODP doctrine: preventing a second patent that is patentably indistinct from a first patent. Because the '356 patent was not a second patent, the court found that the '356 patent’s additional 15 months of term did not unjustly extend the exclusive right on eluxadoline. As such, the later filed, later issued '011 and '709 patent claims are not proper ODP references that could be used to invalidate the '356 patent. The court concluded that holding otherwise “would not only run afoul of the fundamental purposes of ODP, but effectively abrogate the benefit Congress intended to bestow on patentees when codifying PTA.”
Federal Circuit Clarified In re Cellect and Gilead
The court contrasted Allergan with In re Cellect, which established the rule that when evaluating ODP on a patent with PTA, the relevant expiration date is the expiration date including PTA. The decision stated that because Cellect did not challenge whether the reference claims used to invalidate the asserted claims were proper ODP references, the court did not consider the issue in Cellect. The court also confirmed the holding in Gilead that an earlier-filed and earlier-expiring, but later-issued patent can invalidate a later-filed and later-expiring, but earlier-issued patent.
Patent Portfolio Considerations in View of Allergan
This precedential case provides patent owners and applicants fodder when challenging assertions of invalidity or non-patentability, respectively, when the assertions do not align with the rationales for ODP as articulated in Allergan. In particular, this court focused on the rationale of preventing an unjust extension of patent term by a second patent claiming a patentably indistinct invention. Although not an issue in the present case, another rationale for ODP is the concern that two patents with patentably indistinct claims could be separately owned and asserted against an accused infringer.3
This case also highlights the importance of thoughtfully planning the claim scope and timeline of patent applications sharing a priority claim. For example, obtaining broad genus claims in a first patent, such that the claims could not be invalidated by a later-filed, later-issued continuing application under Allergan. The continuing application’s claims should be either patentably distinct from the genus claims or fall within the safe harbor provision (35 U.S.C. 121). In addition, the claims of pending applications should be carefully reviewed for alignment with the holding and dicta of Allergan. This is especially important before payment of the issue fee for allowed patent applications.
[1] Allergan USA, Inc. v. MSN Laboratories Private Ltd., 24-1061 (Fed. Cir. 2024).
[2] Sun Pharmaceutical further alleged that asserted claims of U.S. patents 11,007,179, 11,090,291, 11,160,792, and 11,311,516 were invalid for lack of written description. In a split decision, the court held that these asserted claims were not invalid for lack of written description.
[3] One way to address the concerns underlying the ODP doctrine is to file a terminal disclaimer, which disclaims the terminal part of a subject patent that would extend beyond the expiration date of the reference patent and requires that the subject patent is only enforceable during such period it is owned by the same party or parties as the reference patent. For further information regarding terminal disclaimer practice, please see Wilson Sonsini’s client recent publication: https://www.wsgr.com/en/insights/uspto-proposes-new-requirement-for-terminal-disclaimers-that-amounts-to-a-significant-change-from-current-practice.html.
