Double Trouble for Double Patenting or When Does My Patent Expire?

Intellectual Property Law

The Federal Circuit recently clarified the interplay between obvious-type double patenting (ODP) and patent term adjustments (PTA) granted pursuant to 35 U.S.C. § 154(b). In In re Cellect, the Federal Circuit explained that ODP is considered after any PTA is applied, which could cause patents with terms that have been adjusted to be susceptible to an ODP challenge when they otherwise would not have been.

A patent filed today will generally expire 20 years from the patent’s filing date or the earliest date from which it claims priority. For example, a patent filed on January 1, 2015, will, absent any extensions or adjustments, expire on January 1, 2035, regardless of how long it took to issue. If the inventor files a continuation application in order to claim variations of the invention disclosed in the original patent and claims priority to his original patent filed on January 1, 2015, the patent issued on the continuation application will also, absent any extensions or adjustments, expire on January 1, 2035, even if it was filed years after the original patent.

This has not always been the case. Prior to the 1995 implementation of the Uruguay Round Agreements Act (URAA), which sought to harmonize the term of U.S. patents with those of the United States’ major trading partners, the term of a U.S. patent was 17 years from the patent’s issue date. For example, under the prior statute, if the original patent was filed on January 1, 1980, and issued on February 1, 1983, it would expire on February 1, 2000. A continuation patent filed on January 31, 1983, and issued on March 1, 1985, would expire on March 1, 2002, more than two years later, even if its claims were mere obvious variations of the claims of the original patent. Under this scenario, the inventor would essentially get 19 years of patent protection for his single invention. To prevent this, the courts created the ODP doctrine, under which an examiner or a court could reject or invalidate a patent with claims that are a mere obvious variation of the claims of an earlier-expiring reference patent. A reference patent is often a parent to a continuation patent, but it does not need to be as long as it has an inventor in common and/or the same owner or assignee as the patent being examined.

A patentee can, if the reference patent has not expired, cure an ODP challenge by filing a terminal disclaimer, which disclaims any part of the term of the new patent that would extend past the expiration date of the reference patent and also states that the new patent will only be enforceable as long as it and the reference patent remain commonly owned. Because the law now forces many related patents to expire on the same day, ODP has become less important for preventing a time-wise extension of patent monopolies, but ODP rejections are still made by patent examiners and patent applicants are still overcoming those rejections by filing terminal disclaimers.

The patent law also provides two mechanisms for extending or adjusting the expiration date of a patent. The first is 35 U.S.C. § 156, which was added as part of the Hatch-Waxman Act in 1984.1 It provides up to five years of patent term extension (PTE) to account for delays during a regulatory review process for patents claiming products subject to regulatory approval, such as drug patents needing review by the Food and Drug Administration (FDA). Congress later added 35 U.S.C. § 154(b) as part of the URAA, and then amended it in 1999 to create the PTA process to account for the loss of patent term length due to delays caused by the U.S. Patent and Trademark Office (USPTO) during patent prosecution.2

The ODP doctrine and the statutory grant of PTA came together in In re Cellect, Nos. 2022-1293, 2022-1294, 2022-1295, 2022-1296, 2023 WL 5519716 (Fed. Cir. Aug. 28, 2023), where the Federal Circuit decided an appeal from the Patent Trial and Appeal Board (PTAB), which had affirmed an examiner’s rejection of four Cellect patents for ODP during ex parte reexaminations. The four patents at issue all claimed priority to a single parent patent application, but each had been granted PTA of a different length. Consequently, rather than all these patents expiring on the same day, they all expired on different days and all after a fifth patent, which also claimed priority to the same parent patent application but was not granted PTA. None of the patents had been rejected for ODP during the original prosecution, none was subject to a terminal disclaimer, and no terminal disclaimer was possible during the reexaminations because the reference patent had already expired. The Cellect patent family tree is depicted below. The four patents at issue are indicated in red; the ultimate reference patent is indicated in green.3


The question for the Federal Circuit was whether ODP is considered before or after any PTA is applied. If ODP is considered before any PTA, then, before the PTA, all Cellect’s patents would have expired on the same day based on their common claim to priority, and there would not have been an earlier-expired reference patent against which ODP could have been applied. But if ODP is considered after PTA, then the application of PTA caused some Cellect patents to expire later than others, creating the circumstances where ODP could be applied.

Cellect argued that PTA should be treated the same as PTE because both “PTE and PTA were meant to be mandatory term adjustment and extension provisions that restore patent term lost to different administrative delays.” Id. at *6. Cellect pointed out that the Federal Circuit had already held that for PTE, ODP is considered before any PTE is applied, so PTE can never create an ODP situation. See Merck & Co. v. Hi-Tech Pharmacal Co., 482 F.3d 1317, 1322-23 (Fed. Cir. 2007) (“The computation of [PTE] is from the expiration date resulting from the terminal disclaimer and not from the date the patent would have expired in the absence of the terminal disclaimer.”) and Novartis AG v. Ezra Ventures LLC, 909 F.3d 1367, 1375 (Fed. Cir. 2018) (“a PTE pursuant to § 156 is valid so long as the extended patent is otherwise valid without the extension.”). The Federal Circuit disagreed. Citing the differences in statutory language (§ 154(b) expressly states that the term of a patent cannot be adjusted beyond the expiration date specified in a terminal disclaimer) and the different statutory purposes (“PTE is designed to effectively extend the overall patent term for a single invention due to regulatory delays in product approval. PTA is designed to extend the term of a particular patent due to delays in the processing of that patent.” Cellect, 2023 WL 5519716 at *8), the Federal Circuit held that “ODP for a patent that has received PTA, regardless [of] whether or not a terminal disclaimer is required or has been filed, must be based on the expiration date of the patent after PTA has been added.” Id. at *9 (emphasis added).

For Cellect, the holding meant that, because of the PTA, each of the four challenged patents expired later than another patent that could then serve as the reference patent, creating the situation that allowed them to be challenged for ODP. Because the reference patents had already expired, Cellect was unable to cure this situation with a terminal disclaimer.

Why this matters

In general, patentees consider the grant of PTA a good thing that adds time to their patent monopoly to account for USPTO delays. But now, before deciding to assert a patent, patent owners will want to carefully consider whether any PTA makes their patent vulnerable to an ODP challenge. If it does, they will want to decide how they plan to address that challenge, either by defending their patent on the merits (i.e., arguing that the new claims are not obvious in light of the reference claims) or, if they’re able, by filing a terminal disclaimer.

1 The formal name of the Hatch-Waxman Act is The Drug Price Competition and Patent Term Restoration Act (Public Law 98-417).

2 On average, over half of issued patents receive some PTA.

3 For some patents, the ODP reference patent was an earlier-expiring patent that had received PTA, but the invalidation of all claims under ODP can be traced back to the one patent that did not receive any PTA.



pursuant to New York DR 2-101(f)

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