The Effect of an Expiration Date on Obviousness-Type Double Patenting

Bernadette McGann | June 25, 2014

Gilead Sciences, Inc. v. Natco Pharma Ltd. 

April 22, 2014

Panel: Rader, Prost and Chen.   Opinion by Chen. Dissent by Rader.


An objective of the obviousness-type double patenting doctrine is to preserve the public’s right to use not only the exact invention claimed by an inventor when his patent expires, but also obvious modifications of that invention that are not patentably distinct improvements.  Thus, a patent that issues after but expires before another patent may qualify as a double patenting reference for that other patent.


Gilead owns patents 5,952,375 and 5,763,483 (hereinafter ‘375 and ‘483, respectively), both regarding the inhibition of viruses through selective interference with certain enzymes.  ‘375 and ‘483 are not part of the same family of patents, do not claim priority to any common application, will expire at different times, and were not before the same Examiner.  Court noted that these patents issued from separate chain of applications.

Overview of the filing date, issue date and expiration of ‘483 and ‘375

Illustration - Gilead Science v Natco pg 4





At page 4.

After ‘483 issued, Gilead filed a terminal disclaimer in the application that led to ‘375, which limits the patent term of ‘375 to not extend beyond the term of ‘483.  No terminal disclaimer is filed for the ‘483 patent.

In March 2011, Gilead sues Natco for infrignment of the ‘483 patent.  Natco asserts that the ‘483 patent is invalid for obviousness-type double patenting in view of claim 8 of the ‘375 patent.  In December 2012, with regards to the double patenting defense, the District Court granted summary judgment in favor of Gilead.  The District Court held that a later-issued but earlier-expiring patent cannot serve as a double patenting reference against an earlier-issued but later-expiring patent.  At page 5.

The CAFC vacated the judgment of the District Court and remands the case.  The CAFC held that:

  • “[I]t cannot be that a patentee can obtain two patents in sequence ‘substantially for the same invention [] and improvements’; ‘it would completely destroy the whole consideration derived by the public for the grant of the patent, viz. the right to use the invention at the expiration of the term.  Odiorne v. Amesbury Nail Factory, 18 Fed. Cas. 578, 579 (C.C.D. Mass 1819).  Thus, the doctrine of double patenting was primarily designed to prevent such harm by limiting a patentee to one patent term per invention or improvement.”  At page 7
  • “The principles of the [obviousness-type double patenting rejection] doctrine as a means to preserve the public’s right to use not only the exact invention claimed by an inventor when his patent expires, but also obvious modifications of that invention that are not patentably distinct improvements. See Eli Lilly & Co. v. Barr Labs., Inc., 251 F.3d 955, 967 (Fed. Cir. 2001).”  At page 8.
  • In Robeson, the Court held that “a terminal disclaimer should be a permissible means to overcome the prohibition on double patenting when it aligns the expiration dates of an inventor’s several patents that claim mere obvious variations of the same invention to create a single term of limited exclusivity.” Application of Robeson, 331 F.2d 610, 614. (CCPA 1964).   At page 10.

The CAFC states that the “bedrock principle of our patent system that when a patent expires, the public is free to use not only the same invention claimed in the expired patent but also obvious or patentably indistinct modifications of that invention….  [P]rinciple is violated when a patent expires and the public is nevertheless barred from practicing obvious modifications of the invention claimed in that patent because the inventor holds another later-expiring patent with claims for obvious modifications of the invention.” At page 11.

The CAFC held that “the earliest expiration date of all the patents an inventor has on his invention and its obvious variants best fits and serves the purpose of the doctrine of double patenting. Permitting any earlier expiring patent to serve as a double patenting reference for a patent subject to the URAA guarantees a stable benchmark that preserves the public’s right to use the invention (and its obvious variants) that are claimed in a patent when that patent expires.” At page 15.  Thus, an earlier-expiring patent can qualify as an obviousness-type double patenting reference for a later-expiring patent.  A terminal disclaimer can preserve the validity of the later‑expiring patent by aligning its expiration date with that of the earlier-expiring patent.

In a footnote, the CAFC held that decision is applicable to “only obvious variants of an invention, not separately patentable improvements.”  At page 11.

Gilead argued that the court should focus on the potential term extension of the ‘483 patent, not the ‘375 patent since the ‘483 patent issued first.  That is, Gilead argued that extending the term of ‘483 was not at issue because ‘483 issued prior to ‘375 issued.  Gilead cites several cases where the double patenting bar is applied to the second or later issued patent.

The CAFC dismissed this argument since the case law cited by Gilead did not apply URAA (Uruguay Round Agreements Act of 1994 – changed the term for a U.S. patent from seventeen years from the patent issue date to twenty years from the earliest effective filing date) and patents in those cases for which the expiration date was inextricably intertwined with the issuance date.  Moreover, the CAFC held that the focus must be on ensuring that the restriction on the public’s freedom to use the invention claimed in a patent and all obvious modifications of it after that patent expires is not compromised.  “Thus, the focus on controlling the patent term of later issued patents in those cases makes perfect sense: before the URAA, later issued patent expired later.  At pages 12 and 13.

Pre-URAA – For double patenting inquires, looking to patent issue dates was a reliable source for determining patent expiration.  Post-URAA – it is the comparison of the expiration date of various patents that should control, not merely the issuance date.

The CAFC held that relying solely on issuance date in post-URAA patents has the following pitfalls.

1)      Terms of patents could be subject to significant gamesmanship during prosecution:

a.  “Inventors could routinely orchestrate patent term extension by (1) filing serial applications on obvious modifications of an invention, (2) claiming priority to different applications in each and then (3) arranging for the application claiming the latest filing date to issue first.  Thus, inventors may obtain additional patent term exclusivity for obvious variants of their invention while also exploring the value of an earlier priority date during prosecution.” At page 13.

2)      Lead to arbitrary, uncertain and/or prone to gamesmanship.

a.  Under Gilead’s position, if ‘375 issued the day before the ‘483 patent, then the last 22 months of the term of the ‘483 patent would be an improper extension of patent term.  However, if the ‘375 patent issued the day after the ‘483 patent, then the last 22 months of the term of ‘483 patent would be a proper extension of patent term. At page 14.

Illustration 1Gilead Science v Natco pg 14





Illustration 2 Gilead Science v Natco pg 14





Further, the CAFC asserts that their holding is consistent with the MPEP.  Section §804.I.B.1 states that where two pending patent applications filed by the same inventor are subject to provisional obviousness-type double patenting rejection over each other, a terminal disclaimer is required in the later of the two application (which the hypothetical anticipates to have the later expiration date) before that application can issued.

As additional support of their holding, the CAFC cites Braithwaite, which holds that “using the expiration date as a bench-mark in post‑URAA cases of obviousness-type double patenting preserves the ability of inventors to use a terminal disclaimer of later-expiring patents to create one expiration date for their term of exclusivity over their inventions and obvious variants, ‘which is tantamount for all practical purposes to having all the claims in one patent’.”  Application of Braithwaite, 379 F.2d 594, 601 (CCPA 1967).”  At page 15.


Rader stated that the “courts should be reluctant to create or expand judge-made exceptions to statutory grants.” At page 3.  Rader notes that “Gilead’s subsequent ‘375 patent did not extend the term of the earlier-issuing patent ‘483.  The ‘375 patent claims priority to an earlier filing date and consequently expires first.  Notably, if the ‘375 patent had never issued, Gilead would certainly be entitled to the ‘483 patent’s 2016 expiration date.” At pages 3 and 4.  Further, Rader notes that since ‘375 and ‘483 are own by the same entity, there is no risk of separate parties suing on the two patents, which is a secondary policy concern addressed by the doctrine of obviousness-type double patenting.

Rader asserts that “the court relies on the flawed assumption that upon the expiration of a patent, the public obtains an absolute right to use the previously-claimed subject matter.”  At page 5.  Rader holds that the correct position is that upon the expiration of a patent, that particular expired patent is no longer a bar to the public’s use of the claimed subject matter.

While Rader does not give specifics, he notes that he is concerned about the interplay between the decision of the Court and the AIA requirement of first-inventor-to-file requirement.

Take Away:

Caution should be used if a one-way terminal disclaimer is being filed.  In light of Patent Term Adjustment (PTA) and Patent Term Extension (PTE), it may not be possible to know the expiration date of a patent during prosecution.

Applicants who have a separate chain of applications, i.e. potentially related but do not share common priority, may consider tracking possible PTA during prosecution.  However, PTE is not always known prior to the end of prosecution.

When there is a separate chain of applications, Applicants may consider filing an Information Disclosure Statement early in prosecution, disclosing any applications which may be related.  Applicants may then address potential obviousness type double patenting rejections early in prosecution.

It may be strategically advantageous to allow a patent to go abandon.  According to Rader, if ‘375 had been abandoned, then the patent term of ‘483 would not have been in jeopardy.

Full Opinion

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