In its late August 2023 decision in In re: Cellect, LLC, the US Federal Circuit resolved a question that has lingered since the US Congress’s 1999 enactment of patent term adjustment. Nos. 2022-1293, 2022-1294, 2022-1295, 2022-1296 (Fed. Cir. August 28, 2023). The court held that patent term-adjusted patents are subject to obviousness-type double patenting (ODP) limitations in view of related patents with the same priority date and with shorter or no patent term adjustment. Specifically, a claim in a patent having a later expiration date solely because of patent term adjustment can be invalidated for obviousness-type double patenting over the claim of an earlier-expiring patent in the same family.

In In re: Cellect, LLC, the Federal Circuit affirmed that claims in four of Cellect’s patents are unpatentable for ODP. Cellect’s principal argument on appeal was that Cellect’s claims should have been evaluated for ODP based on their expiration dates before the addition of any patent term adjustment, just as the Federal Circuit had decided for claims subject to patent term extension under 35 USC § 156, a facially-similar statutory extension of patent term.

The United States Patent and Trademark Office (USPTO) argued that, even aside from differences in the statutory language of patent term adjustment and patent term extension, the issue should be controlled by the Federal Circuit’s previous explanation in AbbVie v. Mathilda & Terence Kennedy Inst. of Rheumatology Tr. (764 F.3d 1366, 1373 (Fed. Cir. 2014)) that the ODP doctrine remained viable to prevent patent term adjustment from allowing patents filed at the same time to issue with patentably-indistinct claims and different effective patent terms.

In affirming the determination by the USPTO Patent Trial and Appeal Board that the obviousness-type double patenting-rejected claims were unpatentable, the Federal Circuit held that “[ODP] for a patent that has received [patent term adjustment], regardless whether or not a terminal disclaimer is required or has been filed, must be based on the expiration date of the patent after [patent term adjustment] has been added”. In other words, patent term adjustment cannot cause a subject patent’s patentably-indistinct claims to outlive an earlier-expiring (with or without patent term adjustment) reference patent.

This ruling also clarifies that a terminal disclaimer filed to overcome an ODP issue must disclaim any patent term adjustment beyond an earlier-expiring reference patent’s expiration date, including any patent term adjustment granted to the reference patent. The court rejected Cellect’s argument that patent term adjustment should be treated in an ODP analysis like patent term extension as “an unjustified attempt to force disparate statutes into one”.

Importance of reviewing patent family portfolios

The impact of the court’s decision in Cellect was particularly acute because the reference patents on which the ODP findings were based had all expired, foreclosing Cellect’s ability to file terminal disclaimers to overcome those findings.

Patent owners can avoid Cellect’s fate by reviewing their patent family portfolios prior to the expiration of the first-to-expire family member, when terminal disclaimers are still available as a tool for curing potential ODP issues. Additionally, other useful patent prosecution and litigation strategies can be implemented by international practitioners in view of Cellect to minimise the likelihood of ODP problems and address those that arise in ways that maximise coverage and patent term.


For prosecuting original applications, consider prosecuting multiple, similar independent claims. If the claims are subjected to a restriction requirement, filing a safe-harbor divisional application can shield the claims from an ODP rejection.  If the claims are not subjected to a restriction requirement and are allowed, the claims will issue in one patent and will not face any ODP challenge.

For prosecuting pending applications and granted patents, be sure to docket a reminder prior to expiration of the first-to-expire member of patent family to determine if any family members need attention. After review, if any open, non-safe-harbor applications have patentably-indistinct claims, consider (1) amending the claims, (2) requesting the Examiner address obviousness-type double patenting, or (3) filing a preemptive terminal disclaimer to address a potential ODP challenge.


For litigating patents, pre-suit diligence, be aware of ODP challenges during pre-suit diligence. Patentably-indistinct claims in relevant patents are at risk for ODP, even if they have the same expiration date.

Consider filing a terminal disclaimer to address an ODP challenge, but remember: (1) terminal disclaimers limit the term for all claims in the patent, (2) obviousness-type double patenting invalidates only patentably-indistinct claims, and (3) terminal disclaimers are not available if the reference patent has already expired.

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