Claim Preclusion Barred Subsequent Infringement Action Despite Intervening Reexamination

In Senju Pharmaceutical Co. v. Apotex Inc., No. 13-1027 (Fed. Cir. Mar. 31, 2014), the Federal Circuit affirmed the district court's dismissal of a second patent infringement action as barred by claim preclusion, holding that the intervening reexamination proceeding did not create a new cause of action.

U.S. Patent No. 6,333,045 ("the '045 patent") is directed to an ophthalmic, pharmaceutical solution containing the antimicrobial drug Gatifloxacin in combination with disodium edetate. Apotex Inc. and Apotex Corp. (collectively "Apotex") filed an ANDA with the FDA, seeking to market a generic version of the ophthalmic solution, and Senju Pharmaceutical Co., Ltd., Kyorin Pharmaceutical Co., Ltd., and Allergan, Inc. (collectively "Senju") sued Apotex for patent infringement. In this first suit, the district court concluded that Apotex infringed claims 1-3, 6, 7, and 9 of the '045 patent, and that claims 1-3 and 6-9 were invalid as obvious.

Before final judgment was entered in the first suit, Senju requested reexamination of claims 1-3, 6, 8, and 9 of the '045 patent, and the PTO granted the request. During reexamination, Senju amended claim 6 and added new independent claim 12 and new dependent claims 13-16. The PTO canceled claims 1-3 and 8-11, and certified amended claim 6 and new claims 12-16 as patentable. Still pending final judgment in the first suit, Senju filed a second suit against Apotex, seeking DJ of infringement of claims 6 (as amended) and 12-16. The district court subsequently issued a final judgment in the first suit, and Apotex filed a Rule 12(b)(6) motion to dismiss the second suit based on claim preclusion. The district court granted the motion, and Senju appealed.

On appeal, the Federal Circuit looked to the Third Circuit's three-prong test for claim preclusion. The Court noted that the parties agreed that the first suit resulted in a final judgment on the merits and involved the same parties, but disagreed over whether the suits were based on the same cause of action. The Federal Circuit applied its own law to this question, looking first to whether the products were "essentially the same" and second to whether the patents were the same. Regarding the first question, the Court concluded that the product for claim preclusion purposes was the drug described in the ANDA, and that both suits were thus based on the same product.

"[C]laims that emerge from reexamination do not in and of themselves create a new cause of action...