By Stephen L. Grant, Sr. Atty, Standley Law Group LLP

"Double patenting" comes in two different flavors. One flavor is a bit bland; it doesn’t have the depth of nuance. But the second flavor, and especially its US patent law overtones, makes for tasty reading. And so, a sample of Gilead Sciences, Inc. v. Natco Pharma Limited 1 is suggested to you.

Reprinted from the Summer 2014 issue of Intellectual Property News originally published by the Ohio State Bar Association Intellectual Property Section.

The first type of double patenting is the statutory interpretation of 35 USC 101 that an inventor has a right to "a patent," not multiple patents, on an invention. This doctrine is well-established in most patent offices around the world. A commonly-cited US basis for the principle is Miller v Eagle Manufacturing Co.2 Statutory double patenting is easy to understand in a system where a patent issues for a fixed term after the issue date, as the US had before 1994, as allowing a second patent for the same invention would extend the patent. It would also be deceptive by allowing someone to have liability for infringement, even if they were only practicing what the expired patent would indicate to be in the public domain. This deceptiveness would mean that the inventor had not fully disclosed the invention and had not promised to allow full use of the patent after its expiration.3 As in many doctrines of our patent laws, Justice Story noted this doctrine as early as 1819.4

The second flavor of double patenting is a creation of the judiciary.5 If an inventive entity files an application in which at least one of the claims would be obvious over the claims in an earlier-filed application, US law allows that the second-filed application to also issue, provided that the applicant agrees to disclaim the portion of the term of the later-issued patent that would extend beyond the expiration of the earlier-filed application.

An initial reaction to obviousness-type double patenting is that requiring the inventor to disclaim part of the term is somehow unfair to the inventor. However, it is important to keep in mind that the later-filed application is only able to issue with claims that are obvious variants of the earlier-filed subject matter because the US law prevents the earlier-filed application from being used against the later-filed application, due to common ownership. Expressed somewhat differently, a different inventor who disclosed the same invention as the later-filed application would be unable to avoid the prior art effects of the earlier-filed application of another, and no patent would issue to the different inventor.

The foregoing principles allow continuation-in-part applications in the US, primarily due to the grace period afforded to the inventor under US law.6 In the "absolute novelty" elsewhere in the world, and the lack of terminal disclaimers, the later-filed application, even by the same inventor, is barred from patentability.

If an inventive entity files an application in which at least one of the claims would be obvious over the claims in an earlier-filed application, US law allows that the second-filed application to also issue, provided that the applicant agrees to disclaim the portion of the term of the later-issued patent that would extend beyond the expiration of the earlier-filed application.

Obvious-type double patenting is usually seen in a case where the earlier-filed application is in the same chain of applications and also issues first. It is also common for the Patent Office to have the same examiner assigned to each of the applications. Under these facts, the examiner is likely to see the double patenting situation and to require the terminal disclaimer before allowing the claims in the later-filed application. That case is well-established in the MPEP.7

Gilead, however, does not present the usual case. The applicant filed a US provisional application in late February 1995 and followed the provisional application with a properly-filed non-provisional application on 26 February 1996. When this "earlier-filed" application issued on 14 September 1999, it had an expiration date of 27 February 2015, based on the non-provisional application’s filing date. The same inventors at Gilead filed a separate application on 27 December 1996, making it the "later-filed" application. But it issued more quickly, on 9 June 1998, so the expected expiration date would be 27 December 2016, which is more than a year after the expiration of the earlier-filed application. After the later-filed application issued, Gilead filed a terminal disclaimer in the earlier-filed application, based on the later-filed application’s expiration date. But, as you might have noted, there is no terminal period in the earlier-field application that can be disclaimed, as it expires earlier. Note that there would have been a terminal portion of the earlier-filed application to disclaim under the "17 years from issue date" provisions that existed in the US prior to 8 June 1994. Note also that the prosecutions of each of the Gilead applications occurred shortly after this change in patent term.

The bottom line, however, is that no terminal disclaimer was ever made in the later-filed application. And that is the problem. Instead of looking at expiration dates in deciding whether a terminal disclaimer was needed, the Patent Office and Gilead looked at the respective issue dates.

When Gilead asserted both patents against Natco, the District Court for the District of New Jersey determined that Natco infringed both patents, even though Natco had argued that the earlier-filed application operates as an obviousness-type double patenting reference, an argument rejected by the District Court as not possible.

The Federal Circuit agreed with Natco, reversing and remanding to the trial court. While they did not actually declare the later-filed application invalid, their remand will probably end up with the District Court doing that on remand. Proceedings “consistent with this opinion” don’t leave a lot of wiggle room to the District Court.


  • 1 2014 LEXIS ____(Fed Cir case 2013-1418, 22 April 2014). The majority opinion is by Judge Chen, with a dissent by then Chief Judge Rader, who resigned from the Court effective from 30 June 2014.
  • 2 151 US 186 (1894).
  • 3 Gilead, slip opinion at 6.
  • 4 Slip opinion at 7. While Story may have noted the concept of double patenting, this first type is truly statutory, based on the equivalent of 35 USC 101 in lace at that point.
  • 5 Although the doctrine originated in judicial cases, it has been codified in 35 USC 253 as a part of the 1952 Patent Act.
  • 6 This principle did not change with the implementation of the "first inventor to file" standard of the American Invents Act, effective from 16 March 2013.
  • 7 Manual of Patent Examining Practice, the guide used by the US Patent and Trademark Office to advise its examiners on accepted practices.
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Double Trouble? by Stephen L. Grant is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.