This month, in Allergan USA, Inc. v. MSN Laboratories Private Ltd., the Federal Circuit added to the ongoing patent-family drama surrounding when patents in the same family can invalidate one another. The Allergan holding is fairly narrow and makes intuitive sense: a “first-filed, first-issued” patent cannot be invalidated for Obviousness-type Double Patenting (ODP) based on a later-filed, later-issued patent with an earlier expiration date. But this outcome was not guaranteed in view of the court's recent precedent regarding nearly identical issues in In re Cellect, LLC, where the challenged family patents were deemed invalid.  

For now, Allergan appears to provide a carve-out to In re Cellect that safeguards “first-filed, first -issued” patents from being invalidated by their later-filed, earlier-expiring child patents. But In re Cellect is pending on appeal to the U.S. Supreme Court, and its outcome, along with potential rule changes proposed by the U.S. Patent and Trademark Office (USPTO), could still have wide-ranging effects on patent portfolio management strategies and the validity of existing portfolios. 

How Did We Get Here?

Flashing back to August 2023, In re Cellect, LLC involved a patent family with several patents challenged under ODP based on several reference patents. Because of varying delays during prosecution across the different patents in the family, each patent received different amounts of Patent Term Adjustement (PTA) and thus expired on different dates. But each respective reference patent expired before each of their respective challenged patents, leaving some time between when the reference patents had expired but the challenged patents had not.  

During ex parte reexamination, the USPTO invalidated each of the challenged patents based on the prior-expiring reference patents in the same family. On eventual appeal to the Federal Circuit, it concluded that “the expiration date used for an ODP analysis where a patent has received PTA is the expiration date after the PTA has been added.” It also noted that "an ODP determination depends on an assessment of obviousness, i.e., whether the claims of a later-expiring patent would have been obvious over the claims of an earlier-expiring patent owned by the same party. If so, absent a terminal disclaimer, the later-expiring claims are invalid." Because none of the challenged patents were subject to any terminal disclaimers and the relevant expiration date for analysis is after PTA is added, the court affirmed the invalidity of the challenged patents. 

The Allergan Carve-Out

Similar to Cellect, Allergan involved a challenge to a patent's validity under ODP using two reference patents in the same family. The reference patents in Allergan were continuations of the challenged patent and were later-filed and later-issued compared to the challenged patent. But because of delays during prosecution, the challenged patent was entitled to 467 days of PTA and therefore expired more than one year after the later-filed, later-issued reference patents. Unlike in Cellect, the challenged patent in Allergan was the first-filed and first-issued patent in the family. And according to the Allergan court, the first-filed, first-issued patent in a family “sets the maximum period of exclusivity for the claimed subject matter and any patentably indistinct variants.” The court went on to hold 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.”

Perhaps anticipating some confusion, the court specifically declared that Allergan ruling is not in conflict with its earlier ruling in Cellect. According to the court, Cellect only requires the court to consider the expiration date of the challenged patent after PTA. It “does not follow, however, that the [challenged patent] must be invalidated by the [reference patents] simply because it expires later.” Further, the court found 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.” In contrast, according to the court, Cellect “did not involve the situation presented here of ODP with respect to the first-filed, first-issued patent.”  

Where Are We Now?

First-filed patents in a family commonly accrue delays during prosecution, resulting in PTA that extends patent life beyond that of subsequent filings in that family. At the same time, for practical reasons, terminal disclaimers are rarely filed in first-filed patents. Accordingly, had the Allergan court affirmed the lower court and invalidated the challenged patent, thousands of first-filed patents would have become vulnerable to challenges under ODP. While such an outcome seemed possible under the Cellect ruling, Allergan appears to have created an important exception that should protect first-filed patents from challenges based on their children. However, under Cellect, that exception does not appear to apply to any other family members. Ultimately, the Supreme Court will soon have a chance to weigh in on this issue in Cellect LLC v. Vidal, and hopefully provide some much-needed clarity applicants can rely on in their patent-family planning.