Expansion of the Double-Patenting Doctrine and its Impact on a Multi-Family Patent Strategy

On April 22, 2014, in a 2-to-1 split decision, the Federal Circuit in Gilead Sciences, Inc. v. Natco Pharma Ltd., No. 13-1418, 2014 WL 1584450 (Fed. Cir. Apr.22, 2014), reversed and vacated a New Jersey District Court's decision holding that Natco Pharma infringed on a patent for the flu drug Tamiflu. The Federal Circuit disagreed with the lower court's ruling that "a later-issued but earlier-expiring" patent cannot serve as the basis for an obviousness-type double patenting invalidity attack against an "earlier-issued but later-expiring" patent. Given this clarification of the double-patenting standard, patentees should be even more mindful of similar claims issuing from multiple patent families.

Gilead Sciences, Inc. v. Natco Pharma Ltd.: Case Background

Pharmaceutical company Gilead Sciences, Inc. is the owner of two patents relating to antiviral compounds. The two patents, U.S. 5,763,483 and U.S. 5,952,375 (the ‘483 and ‘375 patents, respectively), were filed by the same inventors with similar disclosures, but are from separate priority chains, meaning that they do not share any common priority claim. Gilead sued Natco Pharma for infringing the ‘483 patent, but Natco claimed the ‘483 patent was invalid due to obviousness-type double patenting over the claims of the ‘375 patent, arguing, in effect, that the ‘483 patent extended the patent term of the ‘375 patent by 22 months. In response, Gilead argued that the double patenting did not apply because the ‘483 patent issued prior to the ‘385 patent. The district court agreed with Gilead that the judicially created, obviousness-type double patenting doctrine was inapplicable under those circumstances and Natco appealed.

On appeal, the Federal Circuit specifically addressed the issue of whether "a patent that issued after but expires before another patent" can be used as a double patenting reference. Although previous case law only applied double patenting to "later" issuing patents, the three-judge panel decided that the later-issued, first-expiring patent can be used as a double patenting reference against an earlier-issued, second-expiring patent. As illustrated by the chart included on page four of the Federal Circuit's published decision, the ‘375 patent was filed and expired prior to the ‘483 patent, but issued after the ‘483 patent.

Although Gilead filed a terminal disclaimer with the ‘375 patent that referenced the ‘483 patent, the terminal disclaimer in this case had no practical application since the expiration date of the ‘375 antedated the expiration date of the ‘483 patent. Furthermore, no terminal disclaimer had been filed with the ‘483 patent.

In its majority opinion, the Federal Circuit discussed the purpose of the judicially created double patenting doctrine, which prevents a patentee from pursuing multiple patents claiming mere obvious variants of each other in order to extend the patent term of an invention. The court reasoned that the expiration date, not the issue date, is the more relevant date for controlling the patent term and enforcing the principle behind the double patenting doctrine. As such, the Federal Circuit ultimately agreed with Natco and reversed the lower court's ruling.

Impact on Multi-Patent Families

The recent Federal Circuit ruling should play a role in prosecution and enforcement decisions regarding multiple patent families that address similar subject matter. As a starting point, patent owners should be mindful of disclosing potentially related applications and patents to the Patent Office during prosecution. At the very least, patent owners will be better able to persuasively argue that claims should be afforded the full presumption of validity over any double patenting rejections raised subsequent to patent issuance.

Additional precautions may be warranted when dealing with separate chains in a multi-family patent portfolio. If similar patent applications are being pursued from different families, patent owners should consider whether a double-patenting risk exists between the different chains of patent families and evaluate the potential impact on term for both families. To mitigate invalidity risks when creating or maintaining a separate chain in a multi-family patent portfolio, patent prosecutors may want to steer away from claims that could be identified as obvious variants of claims of other "chains" within the patent portfolio.

An important question is whether, as a mitigating measure, a patent owner can file a terminal disclaimer in an invalidated patent (e.g., the ‘483 patent) in view of an earlier expiring patent (e.g., the ‘375 patent). The answer to this question may still be up for debate. While the Federal Circuit discussed in Perricone v. Medicis Pharm. Corp., 432 F.3d 1368 (2005), how a patent owner may overcome double patenting invalidity by filing a terminal disclaimer prospectively, it made no ruling in that case on whether a terminal disclaimer could be filed retrospectively. And even if retrospectively filing a terminal disclaimer was a viable option, the patent owner would need to consider reduced damages due to a shortened patent term or whether expired claims would preclude suit against the infringer.

Litigators will also want to use the new standard established by the Federal Circuit when considering conducting double-patenting reviews either prior to asserting patents or as a part of a litigation defense strategy.  Patent litigators may wish to determine whether separate patent families with similar claims exist within in a patent portfolio.

Patent practitioners should also keep in mind that both independent and dependent claims may serve as the basis for an obviousness-type double patenting rejection – in fact, the Federal Circuit invalidated the claims of the ‘483 patent as obvious variants of one of the dependent claims of the ‘375 patent.

While the recent Federal Circuit ruling provides additional clarity to potential double-patenting issues that might be applicable to multi-family patent portfolios, it also serves as a reminder of potential risks associated with managing such portfolios.