United States: Claim Preclusion Bars Second Lawsuit On Reexamined Claims Previously Held Invalid

Senju Pharmaceutical Co., Ltd. v. Apotex Inc.

Addressing whether claim preclusion bars a second suit asserting reexamined claims against a defendant who was victorious on the merits on the original claims in a first suit, the U.S. Court of Appeals for the Federal Circuit affirmed a district court's ruling that claim preclusion bars a second suit finding that the reexamined claims were not materially different from the original claims. Senju Pharmaceutical Co., Ltd. v. Apotex Inc., Case No. 13-1027 (Fed. Cir., Mar. 31, 2014) (Plager, J.) (O'Malley, J., dissenting).

Senju sued Apotex for patent infringement after Apotex filed an Abbreviated New Drug Application (ANDA) with the U.S. Food and Drug Administration (FDA) requesting approval to manufacture, market and sell a generic version of Senju's Gatifloxacin ophthalmic solution covered by a patent owned by Senju. After a bench trial, the district court found for Apotex. Although the court determined that Apotex's ANDA product infringed all but one of the asserted claims, the court also determined all of the asserted claims were invalid. Senju filed a motion for a new trial or to amend the district court's judgment of invalidity of one of the asserted claims. The district court again found the claim invalid and entered final judgment, a ruling later affirmed by the Federal Circuit.

Meanwhile, the Patent and Trademark Office (PTO) issued a reexamination certificate certifying the patentability of several claims.  Senju then filed a second suit asserting some of the reexamined claims.

On Apotex's motion, the district court dismissed Senju's second suit on claim preclusion grounds. The court reasoned that pursuant to 35 U.S.C. § 305, none of the claims Senju added or amended during the reexamination could be broader than the original claims. As such, the court concluded that the new lawsuit did not create a new cause of action that and dismissed the second suit.  Senju appealed.

The Federal Circuit affirmed. Applying the Court's previous decision in Aspex Eyewear v. Marchon Eyewear ( IP Update, Vol. 16 No. 5), the Court found that the claims that emerged from Senju's reexamination request did not in and of themselves create a new cause of action which did not exist before in the original claims. The Federal Circuit noted that during reexamination claim scope cannot be enlarged and concluded that the reexamined claims were essentially the original claims with the addition of limitations designed to avoid the prior art.

The Federal Circuit did not impose a bright-line rule that a second suit asserting reexamined claims against a defendant who won on the merits in a first suit on the original claims is always barred by claim preclusion.  Rather the Federal Circuit explained that "in the absence of a clear showing that such a material difference exists in a disputed patentable reexamination claim, it can be assumed that the reexamined claims will be a subset of the original claims and that no new cause of action will be created.  This applies whether the judgment in the original suit was based on invalidity of the claims or simply on non-infringement."

In dissent, Judge O'Malley stated that the dispositive issue on appeal was whether Senju's reexamined claims created new patent rights that Senju could not have asserted in the first lawsuit. Judge O'Malley reasoned that because the original claims were invalid, Senju never had any patent rights in the original claims.  As such, Judge O'Malley concluded that Senju should not be precluded from asserting those patent rights for the first time in a second suit on reexamined claims.

Judge O'Malley distinguished Aspex, concluding that it does not support the majority holding. During the first lawsuit in the Aspex case, the district court found that two of the three asserted claims were invalid and that one claim was valid and infringed. Aspex filed a second suit on two claims from the same patent that had been reexamined but had not been adjudicated by the trial court during the first suit in their original forms.  In Aspex, the district court dismissed the second suit, finding the reexamined claims did not materially differ in scope from the original claims.  The Federal Circuit affirmed.

Judge O'Malley reasoned that district court's dismissal of the second suit was effectively based on claim splitting (i.e., asserting in two lawsuits claims from the same patent), a different theory from res judicata, which is the theory applied in Senju.  According to Judge O'Malley, the reexamined claims Aspex asserted in the second lawsuit were essentially the same as the original claims it did not assert in the first lawsuit.  In other words, Aspex had patent rights in the later asserted claims during the first lawsuit. Accordingly, O'Malley reasoned that while the second lawsuit in Aspex was properly dismissed for claim splitting, that rational does not control the fact situation in Senju.

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