Extending Ezra: Federal District Court Declines to “Cut Off” Patent Term Adjustment in View of Alleged Obviousness-Type Double Patenting in Mitsubishi v. Sandoz

In Mitsubishi Tanabe Pharma Corp. v. Sandoz, Inc., the District Court for the District of New Jersey considered whether a patent receiving patent term adjustment (PTA) may be invalidated for obviousness-type double patenting by a later-issuing, earlier-expiring patent in the same family.


Mitsubishi Tanabe Pharma Corp. (MTPC), Janssen, and Cilag sued Zydus and other drug manufacturers in the District of New Jersey alleging patent infringement based on Abbreviated New Drug Applications (“ANDAs”) filed by the defendants that sought approval to market generic versions of MTPC’s Invokana products, which treat diabetes. MTPC asserted U.S. Patent Nos. 7,943,788 (“the ‘788 patent”); 8,222,219 (“the ‘219 patent”); and 8,785,403. Zydus filed a counterclaim alleging that MTPC’s asserted patents were invalid for obviousness and obviousness-type double patenting. On March 22, 2021, the District Court found that MTPC’s patents were not invalid for obviousness or obviousness-type double patenting.

Obviousness-Type Double Patenting

Obviousness-type double patenting is a judge-made doctrine designed to prevent applicants from obtaining additional protection for claims that are not patentably distinct from the claims of an “earlier” US patent or application owned by the applicant (i.e., in which the applicant has an ownership interest). This doctrine is intended to prevent unlawful extensions of the limited patent “monopoly.” The Federal Circuit has addressed obviousness-type double patenting on two recent occasions. In Gilead Sciences, Inc. v. Natco Pharma Ltd.,[1] the Federal Circuit addressed whether a later-issuing, but earlier-expiring, patent can properly be used as a double patenting reference against the other patent. The court held that it could, because to hold otherwise would allow applicants to “game” the patent system to extract additional patent exclusivity for claims that are obvious over a reference patent.

However, the Federal Circuit limited the “Gilead rule” in Novartis AG v. Ezra Ventures LLC,[2] where it found that a challenged patent that expires after a later-filed, later-issued reference patent due to a patent term extension (PTE) cannot be invalidated for obviousness-type double patenting by that reference patent. In so finding, the court noted that, unlike the case in Gilead, the fact pattern in Ezra did not create the same potential for “gamesmanship” relating to structuring of priority dates by the applicant. Importantly for the present case, the court, noting that PTE was established by statute, declined to allow a “judge-made doctrine” to “cut off statutorily-authorized time extension.”

The ‘788 and ‘219 Patents

The MTPC application that issued as the ‘788 patent was filed on January 31, 2005, claiming priority to an application filed on July 30, 2004. On March 24, 2008, the USPTO imposed a restriction requirement on the application, and the applicants elected the composition claims with traverse. The ‘788 patent was issued on May 17, 2011, with 1079 days of PTA, based upon examination delays.

MTPC filed the application that issued as the ‘219 patent on July 1, 2011, claiming priority to the ‘788 patent as a divisional of an intervening divisional application. The ‘219 patent issued on July 17, 2012 without PTA (and was granted 255 days of PTE[3]).


In the present case, Zydus argued that the claims of the ‘788 patent are invalid for obviousness-type double patenting in view of the ‘219 patent. Zydus argued that Gilead sets out a bright-line rule with respect to obviousness-type double patenting wherein the expiration date of a challenged patent controls the obviousness-type double patenting analysis. MTPC argued that the ‘219 patent may not serve as an obviousness-type double patenting reference for two independent reasons. First, the ‘219 patent and ‘788 patent share a priority date, and thus would have had the same expiration date if not for the statutorily-authorized grant of PTA. Second, the claims of the ‘788 patent fall into the safe harbor provided by 35 U.S.C. § 121 because the ‘788 claims were subject to a restriction requirement during prosecution, which led indirectly to the filing of the ‘219 claims in a divisional application.

The present case differs from Gilead and Ezra in a few key respects. Unlike in Ezra, both patents at issue in the present case are post-GATT patents. And unlike in Gilead, the challenged patent here was filed earlier but had a later expiration date than the reference patent. Additionally, the patents at issue in Gilead and Ezra were not from the same family. In the present case, the patents belong to the same family and, thus, would have had the same expiration date if not for the granting of PTA to the ‘788 patent. Further, unlike Ezra, which deals with PTE, MTPC’s ‘788 patent has a later expiration date than the ‘219 patent due to PTA. PTE is time added to a patent’s term to compensate for patent term lost awaiting regulatory approval (such as during a clinical trial) and is assessed jointly by the USPTO and the FDA; it is governed by 35 U.S.C. § 156. In contrast, PTA is time added to a patent’s term to compensate for patent term lost to delays in examination of the patent and is assessed solely by the PTO; it is governed by 35 U.S.C. § 154. Zydus attempted to distinguish the present case from Ezra because, under the statutes, PTA term may be relinquished by a terminal disclaimer, whereas PTE term is not subject to terminal disclaimers. The District Court, however, did not find this argument persuasive.

Finding for MTPC, the District Court found that the ‘219 patent was not a proper double patenting reference, likening the case to Ezra rather than Gilead. The court held that, “[u]nlike in Gilead, the granting of a PTA does not present the potential for gamesmanship by inventors to secure a second, later expiring patent for the same invention.” Additionally, and “[perhaps] more importantly [than the lack of risk of gamesmanship in the awarding of PTA]” the court was persuaded “that ‘a judge-made doctrine’ should not be used to ‘cut off a statutorily-authorized time extension.’ Agreeing with Zydus’s position would mean just that.” Because the court found that the claims of the ‘788 patent were not invalid for obviousness-type double patenting, the court did not address whether the claims qualified for the safe harbor provision of § 121.

In explaining its reasoning, the District Court distinguished a pre-Ezra case[4] in which another district court, confronted with similar arguments, invalidated a patent that had PTA over an earlier-expired patent in the same family; the court did not find that case persuasive in light of the Federal Circuit’s intervening decision in Ezra. Additionally, the District Court dismissed as dicta language from AbbVie, Inc. v. Mathilda[5] that suggests that PTA granted to one of two patents with the same filing date is at odds with the policy considerations underlying obviousness-type double patenting.[6]

Zydus appealed the ruling on April 23, 2021 and the case is presently on appeal before the Federal Circuit.


  • The Gilead Rule may not be a bright-line rule. The present case is on appeal, but interpreting Ezra as the District Court did means that the obviousness-type double patenting analysis does not begin and end with the expiration dates of the patents at issue, particularly if the additional patent term at issue is authorized by statute.

  • The District Court extended the holding of Ezra to apply to PTA as well as PTE. Despite differences between the two patent term extension schemes (originating in different statutes, PTE is not subject to terminal disclaimers), the court held that key features of both (authorized by statute, resistant to applicant “gamesmanship”) lead to the same conclusion: no finding of obviousness-type double patenting.

  • This holding may be read narrowly to apply to patents within the same family, as was the case here. While the court did not explicitly limit its holding in this manner or examine whether the ‘788 patent claims qualify for the § 121 safe harbor, it remains to be seen whether a court would reach the same conclusion in a case involving two commonly owned patents not in the same family.

(Co-authored by Eric Greenwald)

[1] 753 F.3d 1208 (Fed. Cir. 2014).

[2] 909 F.3d 1367 (Fed. Cir. 2018).

[3] Per the Certificate of Extension on file in Patent PAIR.

[4]Magna Electronics, Inc. v. TRW Automotive Holdings Corp., No. 1:12-cv-654; 1:13-cv-324 (W.D. Mich. Dec. 10, 2015).

[5]AbbVie, Inc. v. Mathilda & Terence Kennedy Institute of Rheumatology Trust, 764 F.3d 1366 (Fed. Cir. 2014).

[6]Mitsubishi, No. 17-5319 (FLW)(DEA) (D.N.J. Mar. 22, 2021), fn 43. The District Court also relied on language in the decisions of Ezra and Novartis v. Breckenridge, 909 F.3d 1355 (Fed. Cir. 2018) to distinguish Abbvie.