The Federal Circuit reviews district court ruling over patent validityAugust 7, 2006

Pfizer Inc. (‘Pfizer’) sued Ranbaxy Laboratories and Pharmaceuticals (‘Ranbaxy’) alleging that Ranbaxy’s product described in an Abbreviated New Drug Application (‘ANDA’) infringed two patents covering Lipitor, Pfizer’s blockbuster cholesterol-reducing drug, currently the best selling drug worldwide. The district court issued a favorable ruling for Lipitor, by declaring both patents infringed, one patent’s term extension valid, but invalidating one claim of a second patent. The Federal Circuit affirmed the finding of infringement by agreeing with the district court’s claim interpretation relating to the spatial arrangements of the drug’s structural formula. In its analysis, the court pointed out that patent prosecution in foreign countries was irrelevant to the United States claim construction as a result of the different patentability requirements in European and Danish law. Therefore, statements made in foreign prosecution cannot be used to interpret claims of a U.S. patent. The court also ruled that Pfizer did not improperly obtain a patent term extension from the Patent and Trademark Office. Patent term extensions are controlled by the Hatch-Waxman Act, which allows increased patent terms for products that have undergone regulatory review, such as FDA drug approval, before commercial use or marketing. Ranbaxy alleged that Pfizer obtained the patent term extension as a result of inequitable conduct and that the patent did not actually cover Lipitor, and thus was not eligible for the extension. Because the court had already affirmed the district court’s claim construction, the Federal Circuit rejected Ranbaxy’s argument that Lipitor is not covered by the patent. The court also determined that Ranbaxy failed to establish by clear and convincing evidence that inequitable conduct rendered the extension invalid, because the allegedly withheld information was from related patent applications, not the ‘893 patent.The Federal Circuit then considered the question of validity as a result of failing to meet the statutory requirements for a patent. The court clarified that any failure to comply with statutory requirements of the patent laws can invalidate patent claims. This allowed the court to invalidate dependent claim 6 for failing to place a further limitation on the independent claim.Overall, the court granted Pfizer a mixed ruling by affirming and reversing-in-part the district court