Last week, in Gilead Sciences, Inc. v. Natco Pharma Ltd., the District of New Jersey ruled on summary judgment that Gilead Sciences did not unlawfully extend its patent protection on oseltamivir (Tamiflu), a neuraminidase inhibitor used to treat the flu, covered by U.S. Patent No. 5,763,483 (“the ’483 patent”). Natco Pharma sought to invalidate the ‘483 patent for obviousness-type double patenting in its attempt to market a generic version of Tamiflu prior to the patent’s expiration. Natco had alleged, inter alia, that the claims of the ’483 patent were invalid due to obviousness-type double-patenting over Gilead’s later issued U.S. Patent No. 5,952,375 (“the ’375 patent”).

Obviousness-type double-patenting is a judicially created doctrine that seeks to preclude an inventor from unjustifiably extending patent protection beyond the statutory limit. The relevant inquiry requires a two-step analysis: first, as a matter of law, a court construes the claim in the earlier patent and the claim in the later patent and determines any differences; second, a court decides if the differences between the two claims demonstrate a patentable distinction. Slip op. at 5, citations omitted.

Here, District of New Jersey Judge Susan A. Wigenton was presented with the nuanced-question of whether a later-issued, but earlier-expiring patent can be used as a reference to invalidate an earlier-issued, later-expiring patent. Id. Gilead’s ‘375 patent issued in September 1999 and claimed priority over a family of patent applications dating as far back as February 1995. The ‘483 patent issued in June 1998 from an application filed in December 1995. Analagous questions were previously considered by the District of Delaware last year. See Abbott Labs. v. Lupin Ltd., 2011 WL 1897322 (D. Del. May 19, 2011); Brigham & Women’s Hosp. Inc. v. Teva Pharm. USA, Inc., 761 F. Supp. 2d 210 (D. Del. 2011). And, similar disputes can be expected going forward due to practical anomalies now arising from enactment of the Uruguay Round Agreements Act of 1994 (the “URAA”), which changed the length of patent terms in the United States from the former period of 17 years calculated from the date of patent grant, to 20 years from the earliest effective filing date (effective June 8, 1995)).

The Court agreed with Gilead — and the above-listed District of Delaware opinions — that a later-issued, earlier-expiring patent cannot invalidate an earlier-issued, later-expiring patent on the basis of obviousness-type double patenting. The Court reasoned that the ’375 patent cannot serve as a reference patent since it was issued after, and terminates before, the ’483 patent, and therefore does not unlawfully extend Gilead’s right to exclusivity. Accordingly, the Court found that the lifespan of Gilead’s patents was not a result of gamesmanship, but instead resulted from changes to the patent laws.

Ralph A. Dengler, a former Director in the Gibbons Intellectual Property Department, and Todd M. Nosher, a former Associate in the Gibbons Intellectual Property Department, co-authored this post.